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Abstract

Solution combustion was employed to create a series of ZrO₂:Dy³⁺ (1-11 mol percent) nanoparticles (NPs) using oxalyl dihydrazide (ODH) as the fuel. ZrO₂:Dy³⁺ NPs were subjected to calcination at about 700°C. ZrO₂:Dy³⁺ NPs comprised of 1 to 11 mol% of Dy³⁺ were characterized by employing the X-ray diffraction (XRD), transmission electron microscopic (TEM), UV-visible, and X-ray photoelectron spectroscopic (XPS) techniques. The crystallite diameters of 1 to 11 mol% ZrO₂:Dy³⁺ NPs were observed to range from 8.1 nm to 16.3 nm, exhibiting spherical shape. According to BET tests, the pore volume of ZrO₂:Dy³⁺ NPs was determined to be 100.129 cm³/g. The mean pore diameter of ZrO₂:Dy³⁺ NPs was determined to be 4.803 nm from the Barrett-Joyner-Halenda (BJH) plot. The photoluminescence and photocatalytic dye degradation properties of ZrO₂:Dy³⁺ NPs were investigated. The acid red 88 (AR88) dye was applied to appraise the photocatalytic activities of the NPs under UV irradiation. ZrO₂:Dy³⁺ NPs with 3 mol% Dy³⁺ exhibited improvised photocatalytic activity due to the operative departure of charge carriers. The electrochemical examination of ZrO₂:Dy³⁺ NP modified carbon paste electrode in 0.1 N HCl demonstrated considerable redox potential output, as evidenced by cyclic voltammetric and amperometric measurements. The electrochemical sensor studies on ZrO₂:Dy³⁺ NPs exhibited potentiality towards sensing of highly toxic metals like mercury and lead.

1. Introduction

Because of its outstanding optical and electrical properties, such as strong thermal stability, huge dielectric constant, broad band gap (5–7 eV), and high melting point, zirconium oxide (ZrO₂) was subjected to investigation extensively over the last two decades [1, 2]. Due to its outstanding optical properties, including a high band gap value, a large refractive index, a low optical cost, and improved transparency in the near-infrared and visible ranges, it is a common material in many optical applications [3, 4]. It exhibits a broad band gap and emits photoluminescent (PL) light at short wavelengths [5]. Materials made of rare-earth-doped oxides have unique optical properties like luminescence efficiency and photochemical stability [6, 7].

Tetragonal, monoclinic, and cubic crystal forms are all found in zirconia. The temperature at which each structure is formed is determined by the synthesis method used and the presence of a dopant of any kind; zirconia produced using the sol–gel process, for example, has an amorphous structure, but it can be transformed into tetragonal zirconia after heat treatment at 500°C. The monoclinic structure begins to appear at 800°C, and at 1300°C, the cubic structure emerges. Zirconia can be utilized in biocomposites, combustible cells, catalytic supports, oxygen detectors, and oxygen sensors [8]. Many researchers have looked into the optical characteristics of Dy-doped ZrO₂. For low concentrations of Dy dopant, zirconia has been reported to have improved photoluminescence (3 mol percent). Gu et al. [9] investigated the consequence of calcinations and doping of Dy³⁺ on ZrO₂ nanoparticle luminescence. They discovered that a concentration of 2% Dy in ZrO₂ produces the extreme comparative luminescence intensity having wavelength of 480 nm. The effective photoluminescence in nanocrystalline zirconia was reported at low Dy concentrations [10].

For the production of ZrO₂:Dy³⁺ in this study, the combustion solution method was used (1-11 mol). The crystalline nature and morphological characteristics of the material were studied using a variety of characterization techniques.

The significant and amazing method of removing contaminants from water and wastewater has been photocatalysis. Under UV light illumination, the produced nanomaterial’s catalytic activity for the destruction of acid red 88 (AR88) was evaluated. The photocatalytic activities were explained in relation to the photoluminescence studies and crystallite size, and their applicability in display applications was examined in depth. In 0.1 N HCl solution, cyclic voltammetric and amperometric investigations were also carried out employing electrodes modified with ZrO₂ and ZrO₂:Dy³⁺ (3 mol). Under the detection limit of $2.3602 \times 10^{- 3} mol / L$ , the material demonstrated outstanding catalytic activity for mercury and lead sensing.

2. Experimental

Zr and Dy were obtained from the basic precursors, zirconium (IV) oxynitrate hydrate (ZrO(NO₃)₂·H₂O: 99.9 percent, S D Fine) and dysprosium (III) oxide (Dy₂O₃: 99.9 percent, Merck). The fuel was made in our lab and is called oxalyl dihydrazide (ODH: C₂H₆N₄O₂). For synthesis, oxalic acid, glycine, urea, citric acid, and other fuels were used. ODH with a low ignition temperature produces low molecular weight, innocuous gases as compared to other fuels. Oxide materials produced using ODH as a fuel can be used for a variety of purposes [11, 12]. Initially, Dy₂O₃ is converted to dysprosium nitrate by the dissolution of required quantity of Dy₂O₃ in HNO₃ (1 : 1) for the synthesis of ZrO₂:Dy³⁺ (1–11 mol percent). After the reaction on a sand bath at 80°C was finished, the excess nitric acid was evaporated to produce a transparent terbium nitrate solution. The required amounts of ODH and zirconium (IV) oxynitrate hydrate solution were added to the dysprosium nitrate solution while being continuously stirred to achieve smooth mixing. This heterogeneous mixture (redox) was placed on a Petri plate and introduced into a muffle furnace set to 400°C. The decomposition of the mixture eventually unfolds, culminating in the release of large volumes of gases such as CO₂, H₂O, and N₂. The entire procedure consumes about 5 minutes and leads to the production of ZrO₂:Dy³⁺ nanophosphor.

3. Results and Discussion

3.1. Powder X-Ray Diffraction Analysis

XRD experiments were conducted in order to understand the crystalline nature and true crystallite size of Dy-doped ZrO₂ NPs. PXRD patterns of as-synthesised ZrO₂:Dy³⁺ NPs have been found to be very similar to the pattern as per standard JCPDS card no. 81-1551. The cubic phase of ZrO₂ was used to index all of the diffraction patterns (Figure 1). Cubic, monoclinic, and tetragonal polymorphs of ZrO₂ exist in three different crystalline forms. The cubic/tetragonal phase [13] is the most suitable for technological uses among these. Only the peak associated to ZrO₂ was found after doping ZrO₂ with Dy³⁺. There were no other peaks corresponding to Dy (NO₃)₃ or other contaminants, showing that Zr⁴⁺ ions in the ZrO₂ matrix were replaced by Dy³⁺ ions. A slight peak shift has been observed for ZrO₂ upon Dy doping, which is possibly due to lattice modification and corresponding strain.

Figure 1

X-ray diffraction pattern of Dy³⁺-doped (1-11 mol%) ZrO₂ NPs.

Using full width at half maximum (FWHM) data, $D = k / \cos θ$ [10], the average crystallite size ( $D$ ) was deduced by applying Scherrer’s formula, where $k$ is a constant (approximately 0.90), the X-ray wavelength is 0.15418 nm, and $θ$ is the diffraction angle. The diameters of ZrO₂ crystallite Dy³⁺ (1-11 mol percent) NPs were observed to be between 8.3 and 13.8 nm in size (Table 1).

Table 1

Crystallite sizes of ZrO₂:Dy³⁺ (1-11mol%) NPs.

Samples	Crystallite size (nm)		Strain ( $ε$ ) ×10^-3	SF	$δ$ (10¹⁶ lin m^-2)
Samples	Scherrer’s formula	W–H plot	Strain ( $ε$ ) ×10^-3	SF	$δ$ (10¹⁶ lin m^-2)
ZrO₂:Dy³⁺ (1mol%)	8.3	9.3	14.3	0.3973	1.451
ZrO₂:Dy³⁺ (3mol%)	9.3	6.4	15.1	0.3971	1.156
ZrO₂:Dy³⁺ (5mol%)	10.2	6.9	9.61	0.3974	0.961
ZrO₂:Dy³⁺ (7mol%)	14.9	9.1	4.47	0.3979	0.450
ZrO₂:Dy³⁺ (9mol%)	16.3	5.3	3.73	0.3982	0.376
ZrO₂:Dy³⁺ (11mol%)	13.8	6.6	5.20	0.3984	0.525

Additionally, Dy doping induces a gradual loss of crystallinity of ZrO₂, due to lattice instability and induced strain on the lattice. Previously, the FWHM was assumed to represent a linear combination of crystallite size and lattice strain components [14]. Equation (1) can be used to express the influence of crystallite size and strain on the FWHM. $\begin{matrix} (1) & β \cos θ = ε (4 \sin θ) + \frac{λ}{D}, \end{matrix}$

where $β$ , $θ$ , $λ$ , and $ε$ are FWHM in radians, Bragg angle, wavelength, and strain associated with the NPs, respectively.

A straight line between 4 sin ( $x$ -axis) and cos ( $y$ -axis) is shown in equation (1) (Figure 2).

Figure 2

W–H plots of as-formed ZrO₂:Dy³⁺ (1–11 mol%) NPs.

The line’s intercept ( $0.90 / D$ ) on the $y$ -axis is determined by the crystallite size, and the strain ( $ε$ ) determines the line’s slope ( $D$ ). The tiny variations in the numbers were attributable to Scherrer’s calculation assuming that the strain component was minimal, and the observed broadening of the diffraction peak was credited only to grain size reduction. With a rise in Dy³⁺ concentration, the strain alters. Table 1 lists the results for other structural features such as dislocation density ( $δ$ ) and stacking fault (SF) using the following equations [15]: $\begin{matrix} (2) & δ = \frac{1}{D^{2}}, \\ (3) & SF = [\frac{2 π^{2}}{45 {(3 \tan θ)}^{1 / 2}}], \\ (4) & σ_{stress} = \frac{microstrain}{2} \times E, \end{matrix}$

where $E$ is the elastic constant (Young’s modulus) of the $nanomaterial = 186.21 GPa$ [16].

The presence of the estimated microstrain in the majority of the planes in the current study suggested the presence of tensile stress on the particle’s surface. The residual stress was tensile, with a positive microstrain, causing the PXRD patterns to move to the lower angle side.

3.2. Morphological Studies

Figure 3 depicts the SEM images of ZrO₂:Dy³⁺ (1-11 mol percent) NPs. Because of the large number of gasses generated during combustion, the surface morphology of ZrO₂:Dy³⁺ NPs reveals the presence particle agglomeration which rises with increasing Dy concentration.

Figure 3

SEM images of ZrO₂:Dy³⁺ (1–11 mol%) NPs.

Figure 4(a) depicts the TEM micrograph of ZrO₂:Dy³⁺ (3 mol percent) NM with considerable aggregation of nearly spherical nanocrystals. The recorded crystallite size matched the PXRD data perfectly. A HRTEM image captured from a specific location in Figure 4(b) showed the (111) plane crystal facet of cubic zirconia. The interplanar spacing values of 0.294 nm displayed the (111) plane of cubic zirconia. SAED pattern of ZrO₂:Dy³⁺ (Figure 4(c)) (3 mol%) NM represents cubic ZrO₂ diffraction rings generated from planes (111), (200), (220), and (311) due to cubic zirconia polycrystalline diffraction (Figure 4(b)). The single and pure crystalline cubic ZrO₂ serves as evidence of the value of the current synthesis procedure in producing cubic ZrO₂ NM with good compact size, high purity, and high crystallinity.

Figure 4

(a) TEM image, (b) HRTEM image, and (c) SAED pattern of ZrO₂:Dy³⁺ (3 mol%) NPs.

(b)

(c)

Figure 5 shows the nitrogen adsorption-desorption isotherms of BET and BJH plots (inset), respectively. The IUPAC classifications’ type IV adsorption isotherms are conformed to by the BET plot for the substance [14]. Type IV adsorption isotherms are frequently produced by mesoporous materials, showing the presence of layer-by-layer adsorption on smooth surfaces [15, 16]. The materials’ specific surface area, commonly performed within the linear plots, approximately ranging from $0.05 < P / P 0 < 0.3$ [17] is 100.129 m²/g. Besides, the materials also have H2 type hysteresis loop in accordance with the IUPAC classification [17]; the H2 type hysteresis loop indicates the presence of narrow pore cavity distribution with wide neck size [15]. The BJH plots also confirm the mesoporous nature of the materials with the pore volume and pore diameter values of 0.151 cc/g and 4.803 nm, respectively.

Figure 5

Adsorption-desorption measurements showing BJH plot (inset: pore size distribution).

The XPS technique was used to evaluate the elemental composition, chemical states, and elemental bonding for the produced ZrO₂:Dy³⁺ (3 mol percent), as shown in Figure 6. The recorded wide spectrum of the NM displayed the existence of binding energies ~1072, ~537.6, ~292.2, and~186.3 eV which corroborates to Dy 3d, O 1s, C 1s, and Zr 3d peaks, respectively.

Figure 6

XPS spectra of Dy-doped (3 mol%) ZrO+ NPs.

3.3. Photoluminescence (PL) Studies

Exploration of the energy levels inside the band gap positions yielded crucial knowledge from PL research. PL emission can be used to analyse the effectiveness of migration, charge carrier entrapment, and the destiny of photogenerated electron-hole pairs in semiconductors [18–20]. Because PL emission caused excited electron-hole pairs to recombine, effective separation of charge carrier resulted in a decrease in PL intensity [21, 22].

A PL excitation (PLE) spectrum of 3 mol% Dy³⁺-doped ZrO₂ nanophosphor measured at a fixed emission wavelength of 580 nm corresponds to the electronic transition ( $^{4} F_{9 / 22} ➔^{6} H_{13 / 2}$ ). The PLE bands at 320, 353, 367, 386, 393, and 416 nm were considered to the electronic transitions of $^{6} H_{15 / 2} ➔^{4} H_{11 / 2}$ , ⁴M_17/2, ⁴G_11/2, ⁴I_5/2, ⁴F_9/2, and ⁴I_13/2, respectively. The energy transfer between central oxygen and the f-f transitions of the Dy³⁺ ions are what causes the former band and are attributed to the host’s absorption bands. It proves that the phosphor may be effectively activated by near-UV wavelengths, enabling its use in the creation of white LEDs. Figure 7 displays the emission spectra of ZrO₂:Dy³⁺ phosphors stimulated at 353 nm with 1 to 11 mol percent of Dy³⁺.

Figure 7

PL emission spectrum of ZrO₂:Dy³⁺ (1–11 mol%) NMs excited at 353 nm.

When activated with 352 nm, all of the peaks were observed to be Dy³⁺’s emission peaks, exhibiting energy efficient transfers from the host to Dy³⁺. The luminescence centers stimulated by Dy³⁺ ions were thought to be responsible for the PL spectrum [23]. With the exception of the PL emission intensity, there were essentially insignificant changes in the emission spectra as the Dy³⁺ doping concentration was raised. The peaks observed at 483 nm (blue), 580 nm (yellow), and 672 nm (red) consist of Dy³⁺ transitions corresponding to $^{4} F_{9 / 2} ➔^{6} H_{15 / 2}$ , $^{4} F_{9 / 2} ➔^{6} H_{13 / 2}$ , and $^{4} F_{9 / 2} ➔^{6} H_{11 / 2}$ , respectively. The blue emission corresponding to $^{4} F_{9 / 2} ⟶^{6} H_{15 / 2}$ is due to the magnetic dipole (MD) transition which adheres to the selection rule $∆ J = 0, \pm 1$ and $0 \leftrightarrow 0$ is a forbidden transition. Meanwhile, the yellow ( $^{4} F_{9 / 2} ⟶^{6} H_{13 / 2}$ ) emission corresponds to the forced electric dipole (ED) transition, which follows the selection rule of $∆ L = \pm 2$ and $∆ J = \pm 2$ . This transition is significantly impacted by the surrounding environment, and its intensity is decided by the host and also observed that the feeble red emission for ( $^{4} F_{9 / 2} ⟶^{6} H_{11 / 2}$ ) transition belongs to the electric dipole transition. Dy³⁺ ion transitions from the ⁴F_9/2 energy level to the overlying energy levels ⁶H_15/2, ⁶H_13/2, and ⁶H_11/2 emit PL. The Dy³⁺ ion’s crystal field strength has little effect on the MD transition, while the ED transition can only occur when the Dy³⁺ ion has low symmetry and no inversion center. The intensity of emission increases up to 3 mol percent with an increase in Dy³⁺ concentration from 1 to 11 mol percent before decreasing as a result of concentration quenching. This will clearly show how the PL emission is impacted by the concentration of dopant ions. In fact, luminescence quenching is caused by energy migration, ionic interactions, and cross relaxation to ground energy states, all of which are due to higher concentration of dopant, resulting in the reduction in the mean distance between dopant ions and, in some cases, the creation of dopant clusters. Nevertheless, the excellent emission property of ZrO₂:Dy³⁺ sample shows that it can be used for display application [24].

3.4. Photocatalytic Activity of Acid Red 88 (AR88) Dye under UVA/Sunlight

To investigate the photodegradation activity of Dy³⁺-doped ZrO₂ (1-11 mol percent) NPs, the decolorization of hazardous azo acid red 88 dye was conducted under UV light irradiation for 90 minutes. Acid red 88 degradation was found to be minimal in the absence of ZrO₂:Dy³⁺ and under dark condition. As a consequence, the photocatalytic activity of the excited semiconductors is primarily responsible for the decolorization of the dye. Under UV light, the percentage of acid red 88 decolorization catalyzed by ZrO₂:Dy³⁺ photocatalysts is shown in Table 2. Acid red 88 decolorization rises with increasing dopant concentration up to 11 mol% under UV light, implying that 11 mol% Dy-doped NPs were efficient in separating photo-emitted electron-hole pairs to enhance the photocatalytic degradation efficiency. Acid red 88 was decolorized under solar light with ZrO₂:Dy³⁺ catalysts in the following order: $Zr O_{2} : D y^{3 +} (11 mol %) > ZrO 2 : D y^{3 +} (3 mol %) > ZrO 2 : D y^{3 +} (9 mol %) > ZrO 2 : D y^{3 +} (7 mol %) > ZrO 2 : D y^{3 +} (5 mol %) > ZrO 2 : D y^{3 +} (1 mol %)$ and is shown in Figures 8(a) and 8(b) and Table 2.

Table 2

Kinetic studies under UV light for ZrO2:Dy³⁺ (1–11mol%) photocatalysts.

Photocatalysts	Under UV light
Photocatalysts	$k$ ×10^-3min^-1	$% D$
ZrO₂:Dy³⁺¹mol%	10.95	73.42
ZrO2:Dy³⁺³mol%	21.57	82.65
ZrO2:Dy³⁺⁵mol%	22.76	75.55
ZrO2:Dy³⁺⁷mol%	23.9	79.45
ZrO2:Dy³⁺⁹mol%	31.67	80.52
ZrO2:Dy³⁺¹1mol%	20.09	84.00

Figure 8

(a) Percentage degradation and (b) C/CO for the decolorization of acid red 88 dye under UV light illumination. (c) Effect of pH on photocatalytic degradation of ZrO₂:Dy (11 mol%) catalyst.

(b)

(c)

These findings imply that in the ZrO₂ lattice, an optimal dopant concentration of Dy³⁺ exists, resulting in effective charge carrier separation. To check the performance of photocatalyst under the effect of pH, 11 mol% ZrO2:Dy³⁺ NPs were assessed on the removal of acid red 88 at different values of pH. As the pH decreases, degradation of AR88 increases as shown in Figure 8(c). In acidic medium, photocatalytic activity increases due to the anionic nature of AR88 dye. An electrostatic force is generated between protonated surface of the catalyst ZrO₂:Dy in acidic medium and anionic dye AR88. Hence, dye adsorption on the catalyst surface is enhanced and photodegradation increases. In alkaline medium, there is repulsion between the negatively charged ZrO₂:Dy and anionic dye AR88 molecule; hence, percentage of degradation is less in alkaline medium compared to acidic medium.

Increasing the amount of Dy³⁺ in the catalyst structure resulted in a greater surface barrier and a narrower space charge area, allowing the generated electron-hole pairs to be separated efficiently. Increases in Dy³⁺ concentration up to a certain point cause the space charge layer to be breached, allowing light to penetrate deeper into ZrO2:Dy³⁺ nanoparticles are a type of Dy³⁺ nanoparticle [25]. The half-life of the degradation was calculated for each dopant, and it was found to be 25 min, 11.7 min, 18.3 min, 13.5 min, 12.43 min, and 10.55 min for 1, 3, 5, 7, 9, and 11 mol%, respectively. The respective results are shown in Figure 9. In comparison to the other dopants as mentioned in Table 3, the half-life required for degradation by 3 mol% and 11 mol% was substantially shorter. Hence, it can be concluded that the best suitable dopant for the degradation was 11 mol%.

Figure 9

Half-life plot for the AR88 dye under UV irradiation in the presence of ZrO₂:Dy³⁺ (1-11 mol%) photocatalyst.

Table 3

Summary of the photocatalytic degradation of various photocatalysts and dyes.

Photocatalysts	Light	Dye	Degradation	Ref.
TaON/Bi₂MoO₆	Visible light	Levofloxacin	92.7% (75min)	[29]
SiO₂-Bi₂MoO₆	Visible light	Methyl blue	86.3% (4.5 hours)	[30]
WNR/TNB	Solar light	Rhodamine B (RhB)	96% (80min)	[31]
SCNT6	Xenon lamp irradiation	Congo red	96.2% (60min)	[32]
Ag₂O/TiO₂ (4 : 10)	UV	Methyl orange	93% (6min)	[33]
ZrO₂-doped TiO₂	UV	Rhodamine B	96.3% (60min)	[34]
ZrO₂-doped TiO₂ at 1%wt	UV	Methyl orange and rhodamine B	78.1 and 75.5%	[35]
ZrO₂:Fe³⁺ (2 mol%)	UV	Acid orange 7	98% (90min)	[18]
ZrO₂:Sm³⁺¹¹mol%	Solar light	Acid green G	83.8% (90min)	[36]
ZrO2:Dy³⁺¹¹mol%	UV	Acid red 88	84% (90min)	Present work

According to the proposed mechanism, when light energy strikes the catalyst’s surface, the electron in the valence band (VB) is stimulated to the empty conduction band (CB) (Figure 10), resulting in the production of electron-hole, which further react with the pollutant causing the formation of hydroxyl radicals or singlet oxygen radicals or holes which are responsible for the pollutant degradation [26–28].

Figure 10

Proposed mechanism for the photocatalytic decolorization of AR88 dye over the ZrO₂:Dy³⁺ photocatalyst.

When the migration occurs, these electron-hole pairs will be involved in the redox reaction. When holes combine with the hydroxide ion, it results in the formation of hydroxyl radicals, whereas the superoxide and hydrogen peroxide were produced due to the interaction of electrons with oxygen in the system. The produced superoxide and hydrogen peroxide react together by producing the hydroxyl radicals. In the final step, the produced radicals will react with the pollutant on the metal surface by forming the intermediate compounds in a short time. Finally, these radicals will help in the breakdown of the pollutant to form CO₂ and H₂O.

The 11mol% ZrO2:Dy³⁺ NP reusability test was carried out with an AR88 concentration of 10 ppm, a photocatalyst dosage of 60 mg, and a reaction period of 90 min. To calculate the degrading efficiency loss after each run, six consecutive runs were made. The percentage of degradation for six cycles is 84%, 84%, 83.1%, 82.9%, 82.8%, and 82%, respectively. Even after the sixth run, the degrading efficiency barely decreased may be due to the loss of catalyst during filtration of the catalyst for the next cycle. It was shown that 11 mol% ZrO2:Dy³⁺ NPs can be an effective photocatalyst with high reusability potential for the degradation of AR88 [37–44].

3.5. Electrochemical Sensor Study

3.5.1. Carbon Paste Electrode

To make a carbon paste electrode, a mixture of the prepared sample Dy³⁺-doped ZrO₂, graphite powder, and silicon oil (mass ratio of 15 : 70 : 15) was crushed in a mortar for 20 minutes. This powder was then gently pressed into a Teflon hollow tube (0.3 mm surface area) for further research [45].

3.5.2. Electrochemical Studies

Cyclic voltammetric measurements were performed using the three-electrode assembly in a 50 mL beaker chamber at room temperature. The energetic electrode material ZrO₂ undergoes a few strong Faradaic reactions that lead to a few strong redox peaks [46]. The CV activity of a (3 mol percent) sample in 1 N HCl at different moles using -0.4 to 0.6 V potentials and scan rates of 10 to 50 mV (Figure 11(a)) has been investigated. The observed capacitance was far from that of a typical double-layer electrical conductor, which typically displays a rectangular CV curve.

Figure 11

Cyclic voltammogram of Dy-doped (3 mol%) ZrO₂ sample at different scan rates v/s silver-silver chloride electrode. (b) A plot of cathodic peak current (ip) and the square root of scan rate ( $ν_{1 / 2}$ ) for Dy³⁺-doped (3 mol%) ZrO₂ electrode.

(b)

The linear connection between cathodic peak current (ip) and scan rate ( $v_{1 / 2}$ ) (Figure 11(b)) demonstrates that hydrogen diffusion limits the electrode reaction of Dy³⁺-doped ZrO₂ electrodes. The constructed electrode’s hydrogen diffusion coefficient ( $D$ ) was calculated using the slope of the fitted line in Figure 11(b). The value of $D$ is $1.299 \times 10^{- 6} c m^{2} s^{- 1}$ .

The greatest potential difference between the anodic ( $E_{O}$ ) and cathodic ( $E_{R}$ ) peaks for particular moles is a good predictor of redox reversibility. From Table 4, the ZrO₂ sample with 3 mol% Dy³⁺ dopant has the lowest value, 0.0712 V, which is small when compared to other doped samples, indicating that it is more reversible [47].

Table 4

Oxidation potential ( $E_{O}$ ), reduction potential ( $E_{R}$ ), the difference between $E_{O}$ and $E_{R}$ , diffusion coefficient of Dy³⁺-doped ZrO₂ (1–11 mol%) electrodes.

Name of the sample	$E_{O}$ (V)	$E_{R}$ (V)	$E_{O} (V) - E_{R} (V)$
1% Dy³⁺-doped ZrO₂	0.3732	0.0204	0.3528
3% Dy³⁺-doped ZrO₂	0.4536	0.3824	0.0712
5% Dy³⁺-doped ZrO₂	0.4812	0.3741	0.1071
7% Dy³⁺-doped ZrO₂	0.1808	-0.0792	0.2600
9% Dy³⁺-doped ZrO₂	0.2048	-0.0436	0.2484
11% Dy³⁺-doped ZrO₂	0.2039	-0.0511	0.2550

Figure 12 shows the electrochemical impedance spectra of Dy³⁺-doped ZrO₂ (1–11 mol percent) electrodes with a frequency range varying from 1 Hz to 1 MHz and a 5 mV amplitude. The spectra show a high-frequency load transfer resistance and a low-frequency slope associated with the Warburg resistance. The resistance of the ZrO₂ electrode with Dy³⁺-doped (3 mol%) additive is substantially lower than that of other Dy³⁺-doped ZrO₂ electrodes, suggesting that the 3 mol% additional electrode’s electrochemical reaction is stronger than that of other electrodes [48]. A high-frequency zone marked by a semicircle depicts charge transport at the electrode/electrolyte interface, as well as a low-frequency zone denoted by a straight line that represents electrode capacitance. The diameter of the semicircle arc on the real axis can be used to calculate the charge transfer resistance $R_{ct}$ [49]. The sample’s $R_{ct}$ value is lower because the semicircle arc has a smaller circumference. As the linear curve moves closer to the $y$ -axis, it indicates that the sample has a high capacitance [50].

Figure 12

Nyquist plots of Dy³⁺-doped ZrO₂ (1–11 mol%) electrodes.

Additionally, this circumstance is associated to the ideals of $R_{ct}$ and $C$ yielded by circuit fitting (inset of Figure 12). As illustrated in the Nyquist plots, the resistance gauges the high-frequency semicircle of charge transfer ( $R_{ct}$ ) and the capacitance ( $C$ ) of the double layer.

Table 5 includes values that were obtained by fitting simulation data with an equivalency circuit and relate to the catalytic properties of active materials, such as solution resistance ( $R_{s}$ ), charge transfer resistance ( $R_{ct}$ ), and double-layer capacitance ( $C_{dl}$ ). The charge transfer resistance is low due to the surface catalytic activity of the generated electrodes; when ZrO₂:Dy³⁺ is used, the electrode double-layer capacitance is at its highest (3 mol percent) [34].

Table 5

EIS data of Dy³⁺-doped ZrO₂ (1–11 mol%) electrodes.

Name of the sample	$R_{S}$ (V)	$R_{ct}$ (V)	$C_{dl}$ (F)
1% Dy³⁺-doped ZrO₂	1.948	161.34	0.000226
3% Dy³⁺-doped ZrO₂	0.862	79.32	0.01512
5% Dy³⁺-doped ZrO₂	1.594	94.43	0.003541
7% Dy³⁺-doped ZrO₂	2.595	99.64	0.000865
9% Dy³⁺-doped ZrO₂	2.578	110.52	0.000642
11% Dy³⁺-doped ZrO₂	4.691	194.46	0.000835

The cyclic voltammograms of Dy³⁺-doped ZrO₂ (3 mol%) utilized for mercury and lead sensing are shown in Figure 13. As a consequence, peak position variation due to oxidation and reduction was justified. The development of an anodic oxidation peak at 0.1 V and a cathodic reduction peak at -0.05 V during sensing, as well as the disappearance of the oxidation peak at 0.2 V, shows that the manufactured carbon paste electrode is successful in sensing approach for amounts 1-5 mM.

Figure 13

Cyclic voltammogram of ZrO₂:Dy³⁺ (3 mol%) NP detection of (a) mercury and (b) lead of concentration range 1-5 mM.

(b)

Nevertheless, the cyclic voltammogram of a lead sensor reveals that the entire voltammogram form changes, including the elimination of the oxidation and reduction peaks, but the introduction of an oxidation peak at 0.8 V. For 0 mM mercury and lead, the constructed electrode showed an initial current response of 60 s. Furthermore, the current response increases with continuous introduction of 1 mM mercury and lead (Figure 14), and within the brief time frame of 4 seconds, it approaches a steady current.

Figure 14

Amperometric $i - t$ curve for determination of mercury and lead using ZrO₂:Dy³⁺ (3 mol%).

(b)

This result indicates that the sensor reacts quickly to mercury (0.0003 A) and lead (0.0008 A) oxidation. Finally, the positions of the reduction and oxidation peaks were determined to be considerably different, indicating that the electrodes produced are suitable for sensor applications without impacting other compounds in the sample.

4. Conclusion

A variety of nanoparticles ZrO2:Dy³⁺ (1-11 mol percent) were prepared in this study using a simple and cheap propellant combustion process. The cubic phase of Dy³⁺-doped ZrO₂ NPs was confirmed by PXRD and HRTEM. The average crystallite size, as determined by Debye Scherrer’s and W–H techniques, was found to be between 8.1 and 16.3 nm. The results were very similar to those of the TEM. Under UV light, the photocatalytic activity of ZrO2:Dy³⁺ increased as the concentration of Dy³⁺ rose. All of the photocatalysts displayed increased activity for the breakdown of acid red 88 dye when exposed to UV light. The successful separation of charge carriers was related to the increased activity for the decolorization of acid red 88 under UV radiation. The reversibility of the carbon paste electrode made with Dy³⁺-doped ZrO₂ NPs was excellent (lower value of $E_{O} - E_{R}$ ). Electrochemical impedance measurements revealed a low charge-transfer resistance, confirming its excellent conductivity. The proton diffusion coefficient ( $D$ ) value of the Dy³⁺-doped ZrO₂ electrode material was found to be $1.299 \times 10^{- 6} c m^{2} s^{- 1}$ . These electrodes were particularly successful in sensing heavy metals like mercury and lead in acidic media, according to CV and amperometric studies. The electrode material’s quick reaction (3 s) for sensing medicines at concentrations as low as 1 mM was the study’s highlight. The study shows that Dy³⁺-doped ZrO₂ is a viable and economical electrode material for upcoming sensing applications, which might be scaled up for commercialization.

Footnotes

Data Availability

The data used to support the findings of this study are included within the article.

Conflicts of Interest

The authors declare no conflict of interest.

Acknowledgments

We would like to express our deepest regards for the Centre for Advanced Materials & Technology, M.S. Ramaiah Institute of Technology, Bangalore, India, for their support and help toward characterization analysis.

References

Liao

Bai

J. W.

Lin

Y. C.

Y. Q.

Huang

Duan

X. F.

High-performance top-gated graphene-nanoribbon transistors using zirconium oxide nanowires as high-dielectric-constant gate dielectrics

Advanced Materials 2010 22

5664344

1941 1945

Hanafi

M. F.

Sapawe

The potential of ZrO₂ catalyst toward degradation of dyes and phenolic compound

Materials Today: Proceedings 2019 19

5664344

1524 1528

John Berlin

Lakshmi

J. S.

Sujatha Lekshmy

Daniel

G. P.

Thomas

P. V.

Joy

Effect of sol temperature on the structure, morphology, optical and photoluminescence properties of nanocrystalline zirconia thin films

Journal of Sol-Gel Science and Technology 2011 58

5664344

3 669 676

10.1007/s10971-011-2443-6

2-s2.0-79958774873

John Berlin

Maneeshya

L. V.

Jijimon

Thomas

P. V.

Joy

Enhancement of photoluminescence emission intensity of zirconia thin films via aluminum doping for the application of solid state lighting in light emitting diode

Journal of Luminescence 2012 132

5664344

11 3077 3081

10.1016/j.jlumin.2012.06.027

2-s2.0-84864068373

John Berlin

Anitha

V. S.

Thomas

P. V.

Joy

Influence of oxygen atmosphere on the photoluminescence properties of sol–gel derived ZrO₂ thin films

Journal of Sol-Gel Science and Technology 2012 64

5664344

2 289 296

10.1007/s10971-012-2856-x

2-s2.0-84875692831

Ninjbadgar

Garnweitner

Borger

Goldenberg

L. M.

Sakhno

O. V.

Stumpe

Synthesis of luminescent ZrO₂: Eu³⁺ nanoparticles and their holographic sub-micrometer patterning in polymer composites

Advanced Functional Materials 2009 9

5664344

1819 1825

Hobbs

Briddon

Lester

The synthesis and fluorescent properties of nanoparticulate ZrO₂ doped with Eu using continuous hydrothermal synthesis

Green Chemistry 2009 11

5664344

4 484 491

10.1039/b812149d

2-s2.0-64149128131

Meetei

S. D.

Singh

S. D.

Hydrothermal synthesis and white light emission of cubic ZrO₂:Eu³⁺ nanocrystals

Journal of Alloys and Compounds 2014 587

5664344

143 147

10.1016/j.jallcom.2013.10.159

2-s2.0-84887575939

Wang

S. F.

M. K.

Zhou

G. J.

Liu

S. W.

Yuan

D. R.

Effect of Dy³⁺ doping and calcination on the luminescence of ZrO₂ nanoparticles

Chemical Physics Letters 2003 380

5664344

1-2 185 189

10.1016/j.cplett.2003.09.011

2-s2.0-0141768259

10.

Torres

L. A. D.

la Rosa

E. D.

Salas

Romero

V. H.

Chavez

C. A.

Efficient photoluminescence of Dy₃+ at low concentrations in nanocrystalline ZrO₂

Journal of Solid State Chemistry 2008 181

5664344

1 75 80

10.1016/j.jssc.2007.09.033

2-s2.0-37549053320

11.

Fardood

S. T.

Moradnia

Forootan

Abbassi

Jalalifar

Ramazani

Sillanpää

Facile green synthesis, characterization and visible light photocatalytic activity of MgFe₂O₄@CoCr₂O₄ magnetic nanocomposite

Journal of Photochemistry and Photobiology A: Chemistry 2022 423, article 113621

5664344

10.1016/j.jphotochem.2021.113621

12.

Muthuraman

Dhas

N. A.

Patil

K. C.

Combustion synthesis of oxide materials for nuclear waste immobilization

Bulletin of Materials Science 1994 17

5664344

6 977 987

10.1007/BF02757574

2-s2.0-0028546424

13.

Khataee

Soltani

R. D. C.

Hanifehpour

Safarpour

Ranijbar

H. G.

Joo

S. W.

Synthesis and characterization of dysprosium-doped ZnO nanoparticles for photocatalysis of a textile dye under visible light irradiation

Industrial and Engineering Chemistry Research 2014 53

5664344

5 1924 1932

10.1021/ie402743u

2-s2.0-84893675627

14.

Thommes

Kaneko

Neimark

A. V.

Olivier

J. P.

Rodriguez-Reinoso

Rouquerol

Sing

K. S. W.

Physisorption of gases, with special reference to the evaluation of surface area and pore size distribution (IUPAC technical report)

Chem 2015 87

5664344

9-10 1051 1069

10.1515/pac-2014-1117

2-s2.0-84944241280

15.

Cychosz

K. A.

Thommes

Progress in the physisorption characterization of nanoporous gas storage materials

Engineering 2018 4

5664344

4 559 566

10.1016/j.eng.2018.06.001

2-s2.0-85050497903

16.

Fan

Zeng

Yang

Zhang

Ren

Rational design of asymmetric supercapacitorsviaa hierarchical core–shell nanocomposite cathode and biochar anode

RSC Advances 2019 9

5664344

72 42543 42553

10.1039/C9RA09142D

17.

Walton

K. S.

Snurr

R. Q.

Applicability of the BET method for determining surface areas of microporous metal−organic frameworks

American Chemical Society 2007 129

5664344

27 8552 8556

10.1021/ja071174k

2-s2.0-34447502239

17580944

18.

Gurushantha

Anantharaju

K. S.

Nagabhushana

Sharma

S. C.

Vidya

Y. S.

Shivakumara

Nagaswarupa

H. P.

Prashantha

S. C.

Anilkumar

M. R.

Facile green fabrication of iron-doped cubic ZrO₂ nanoparticles by _Phyllanthus acidus_ : structural, photocatalytic and photoluminescent properties

Journal of Molecular Catalysis A: Chemical 2015 397

5664344

36 47

10.1016/j.molcata.2014.10.025

2-s2.0-84911939299

19.

Prakashbabu

Krishna

R. H.

Nagabhushana

B. M.

Nagabhushana

Shivakumara

Chakradar

R. P. S.

Ramalingam

H. B.

Sharma

S. C.

Chandramohan

Low temperature synthesis of pure cubic ZrO₂ nanopowder: structural and luminescence studies

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2014 122

5664344

216 222

10.1016/j.saa.2013.11.043

2-s2.0-84890038194

20.

Suresh

Ponnuswamy

Mariappan

Effect of annealing temperature on the microstructural, optical and electrical properties of CeO₂ nanoparticles by chemical precipitation method

Applied Surface Science 2013 273

5664344

457 464

10.1016/j.apsusc.2013.02.062

2-s2.0-84876420550

21.

Lovisa

L. X.

Andres

Gracia

M. S.

Paskocimas

C. A.

Bomio

M. R. D.

Araujo

V. D.

Longo

Motta

F. V.

Photoluminescent properties of ZrO²: Tm³⁺, Tb³⁺, Eu³⁺ powders- a combined experimental and theoretical study

Journal of Alloys and Compounds 2017 695

5664344

3094 3103

22.

Nashivochnikov

A. A.

Kostyukov

A. I.

Zhuzhgov

A. V.

Rakhmanova

M. I.

Cherepanova

S. V.

Snytnikov

V. N.

Shaping the photoluminescence spectrum of ZrO₂: Eu³⁺ phosphor in dependence on the Eu concentration

Optical Materials 2021 121, article 111620

5664344

23.

King

Singh

Anand

Behera

S. K.

Nayak

B. B.

Dopant concentration induced tuning of emission in Eu³⁺-doped zirconia nanoparticles

Journal of Physics and Chemistry of Solids 2022 163, article 110575

5664344

24.

Tamrakar

R. K.

Bisen

D. P.

Upadhyay

Photoluminescence behavior of ZrO₂: Eu³⁺ with variable concentration of Eu³⁺ doped phosphor

Journal of Radiation Research and Applied Sciences 2015 8

5664344

1 11 16

10.1016/j.jrras.2014.10.004

25.

Martínez-Hernández

Guzmán-Mendoza

Rivera-Montalvo

Sánchez-Guzmán

Guzmán-Olguín

J. C.

García-Hipólito

Falcony

Synthesis and cathodoluminescence characterization of ZrO₂:Er³⁺ films

Journal of Luminescence 2014 153

5664344

140 143

10.1016/j.jlumin.2014.03.013

2-s2.0-84898079932

26.

Naveen Kumar

Jnaneshwara

D. M.

Nagabhushana

Prashantha

S. C.

Chandrasekhar

Ravikumar

C. R.

Anil Kumar

M. R.

Basavaraju

Shashi Shekhar

T. R.

Premkumar

H. B.

Enhanced photoluminescence, electrochemical and photocatalytic activity of combustion synthesized La₁₀Si₆O₂₇: Dy³⁺ nanophosphors

Journal of Science: Advanced Materials and Devices 2021 6

5664344

49 57

27.

Lakshminarasappa

B. N.

Prashantha

S. C.

Singh

Ionoluminescence studies of combustion synthesized Dy³⁺ doped nano crystalline forsterite

Current Applied Physics 2011 11

5664344

1274 1277

28.

Devi

L. G.

Kumar

S. G.

Reddy

K. M.

Munikrishnappa

Effect of various inorganic anions on the degradation of Congo Red, a di azo dye, by the photo-assisted Fenton process using zero-valent metallic iron as a catalyst

Desalination and Water Treatment 2009 4

5664344

1-3 294 305

10.5004/dwt.2009.478

2-s2.0-71749103269

29.

Renuka

Anantharaju

K. S.

Vidya

Y. S.

Nagaswarupa

H. P.

Prashantha

S. C.

Sharma

S. C.

Nagabhushana

Darshan

G. P.

A simple combustion method for the synthesis of multi-functional ZrO₂/CuO nanocomposites: excellent performance as sunlight photocatalysts and enhanced latent fingerprint detection

Applied Catalysis. B, Environmental 2017 210

5664344

97 115

10.1016/j.apcatb.2017.03.055

2-s2.0-85016490873

30.

Gionco

Hernández

Castellino

Gadhi

T. A.

Muñoz-Tabares

J. A.

Cerrato

Tagliaferro

Russo

Paganini

M. C.

Synthesis and characterization of Ce and Er doped ZrO₂ nanoparticles as solar light driven photocatalysts

Journal of Alloys and Compounds 2019 775

5664344

896 904

10.1016/j.jallcom.2018.10.046

2-s2.0-85055090425

31.

Pratapkumar

Prashantha

S. C.

Dileep Kumar

V. G.

Santosh

M. S.

Ravikumar

C. R.

Anilkumar

M. R.

Shashidhara

T. S.

Nanjunda Swamy

Jahagirdar

A. A.

Alam

M. W.

Chen

Bui

X. T.

Structural, photocatalytic and electrochemical studies on facile combustion synthesized low-cost nano chromium (III) doped polycrystalline magnesium aluminate spinels

Journal of Science: Advanced Materials and Devices 2021 6

5664344

3 462 471

10.1016/j.jsamd.2021.05.009

32.

Wang

Cai

Yang

Liu

Chen

Zhang

Chen

Facile fabrication of TaON/Bi₂MoO₆ core–shell S-scheme heterojunction nanofibers for boosting visible-light catalytic levofloxacin degradation and Cr (VI) reduction

Chemical Engineering Journal 2022 428, article 131158

5664344

33.

Liu

Shaonan

Zhao

Zhou

BiVO₄, Bi₂WO₆ and Bi₂MoO₆ photocatalysis: a brief review

Journal of Materials Science & Technology 2020 56

5664344

45 68

10.1016/j.jmst.2020.04.023

34.

Jun-Yu

Hong-Gang

Shi-Gang

Construction of 1D/1DWO₃nanorod/TiO₂ nanobelt hybrid heterostructure for photocatalytic application

Chinese Journal of Structural Chemistry 2020 39

5664344

6 1019 1028

35.

Wang

Cheng

Fan

Sulfur-doped g-C₃N₄/TiO₂ S-scheme heterojunction photocatalyst for Congo Red photodegradation

Chinese Journal of Catalysis 2021 42

5664344

1 56 68

10.1016/S1872-2067(20)63634-8

36.

Yi-Lan

C. H. E. N.

Yu-Xian

X. U.

Dai-Feng

L. I. N.

Yong-Jin

L. U. O.

Hun

X. U. E.

Qing-Hua

C. H. E. N.

Insight into superior visible light photocatalytic activity for degradation of dye over corner-truncated cubic Ag₂O decorated TiO₂ hollow nanofibers

Chinese Journal of Structural Chemistry 2020 39

5664344

3 588 597

37.

Zhao

Pan

Shao

Lin

Wang

Guo

Solvothermal synthesis, characterization and photocatalytic property of zirconium dioxide doped titanium dioxide spinous hollow microspheres with sunflower pollen as bio-templates

Journal of Colloid and Interface Science 2018 529

5664344

111 121

10.1016/j.jcis.2018.05.091

2-s2.0-85048157898

29886223

38.

Ruíz-Santoyo

Marañon-Ruiz

V. F.

Romero-Toledo

González Vargas

O. A.

Pérez-Larios

Photocatalytic degradation of rhodamine B and methylene orange using TiO₂-ZrO₂ as nanocomposite

Catalysts 2021 11, article 1035

5664344

39.

Gurushantha

Anantharaju

K. S.

Sharma

S. C.

Nagaswarupa

H. P.

Prashantha

S. C.

Mahesh

K. V.

Renuka

Vidya

Y. S.

Nagabhushana

Bio-mediated Sm doped nano cubic zirconia: photoluminescent, Judde Ofelt analysis, electrochemical impedance spectroscopy and photocatalytic performance

Journal of Alloys and Compounds 2016 685

5664344

761 773

40.

Ikram

Asghar

Imran

Naz

Haider

Ul-Hamid

Haider

Shahzadi

Nabgan

Goumri-Said

Kanoun

M. B.

Experimental and computational study of Zr and CNC-doped MnO₂ nanorods for photocatalytic and antibacterial activity

ACS Omega 2022 7

5664344

16 14045 14056

41.

Ul-Hamid

Ikram

Haider

Alam

M. M.

Saeed

Nabgan

Ahmad

Ali

Bake

Asiri

A. M.

In-situ phenylhydrazine chemical detection based on facile Zr-doped MoS₂ nanocomposites (NCs) for environmental safety

Journal of the Taiwan Institute of Chemical Engineers 2021 120

5664344

267 277

42.

Ikram

Hassan

Raza

Haider

Naz

Ul-Hamid

Haider

Shahzadi

Qamar

Ali

Photocatalytic and bactericidal properties and molecular docking analysis of TiO₂nanoparticles conjugated with Zr for environmental remediation

RSC Advances 2020 10

5664344

50 30007 30024

10.1039/D0RA05862A

35518250

43.

Ikram

Tabassum

Qumar

Ali

Ul-Hamid

Haider

Raza

Imran

Promising performance of chemically exfoliated Zr-doped MoS₂ nanosheets for catalytic and antibacterial applications

RSC Advances 2020 10

5664344

35 20559 20571

44.

Kim

Rhee

Song

Kim

Kwon

Y. H.

Lim

D. U.

Kim

I. S.

Mazánek

Valdman

Sofer

Cho

J. H.

All-solution-processed van der Waals heterostructures for wafer-scale electronics

Advanced Materials 2022 34

5664344

45.

Kharatzadeh

Masharian

S. R.

Yousefi

The effects of S-doping concentration on the photocatalytic performance of SnSe/S-GO nanocomposites

2021 32

5664344

2 346 357

10.1016/j.apt.2020.12.013

46.

Anil Kumar

M. R.

Abebe

Nagaswarupa

H. P.

Ananda Murthy

H. C.

Ravikumar

C. R.

Sabir

F. K.

Enhanced photocatalytic and electrochemical performance of TiO₂-Fe₂O₃ nanocomposite: its applications in dye decolorization and as supercapacitors

Scientific Reports 2020 10

5664344

1 1 15

10.1038/s41598-020-58110-7

31988344

47.

Montoya

Pardo

Doménech-Carbó

Alarcón

Structural stability and electrochemical properties of Gd-doped ZrO₂ nanoparticles prepared by sol–gel

Journal of Sol-Gel Science and Technology 2014 69

5664344

1 137 147

48.

Reddy

C. V.

Reddy

I. N.

Shim

Kim

Yoo

Synthesis and structural, optical, photocatalytic, and electrochemical properties of undoped and yttrium-doped tetragonal ZrO₂ nanoparticles

Ceramics International 2018 44

5664344

11 12329 12339

49.

Zhang

K. Y.

Zhai

Preparation of Y-doped ZrO₂ coatings on MnO₂ electrodes and their effect on electrochemical performance for MnO₂ electrochemical supercapacitors

RSC Advances 2016 6

5664344

1750 1759

50.

Smirnova

Gnatyuk

Eremenko

Kolbasov

Vorobetz

Kolbasova

Linyucheva

Photoelectrochemical characterization and photocatalytic properties of mesoporous TiO₂/ZrO₂ films

International Journal of Photoenergy 2006 2006

5664344

85469

10.1155/IJP/2006/85469

2-s2.0-33645221660

Synthesis of ZrO 2 :Dy 3+ Nanoparticles: Photoluminescent,Photocatalytic,and Electrochemical Sensor Studies

Abstract

1. Introduction

2. Experimental

3. Results and Discussion

3.1. Powder X-Ray Diffraction Analysis

3.2. Morphological Studies

3.3. Photoluminescence (PL) Studies

3.4. Photocatalytic Activity of Acid Red 88 (AR88) Dye under UVA/Sunlight

3.5. Electrochemical Sensor Study

3.5.1. Carbon Paste Electrode

3.5.2. Electrochemical Studies

4. Conclusion

Footnotes

Data Availability

Conflicts of Interest

Acknowledgments

References