NiWO4 Nanoparticles Research Articles

Biomimetic (Co, Ni, W)OxNy/WO3 photoelectrocatalyst for robust seawater oxidation

As an intriguing strategy for massive hydrogen production, photoelectrochemical (PEC) seawater splitting compels the anode to be highly hypochlorite-resistant. Inspired by algae, we designed a robust photoelectrocatalyst that WO3 nanorods (NRs) are covered by N/W co-doped (Co, Ni, W)OxNy nanosheets (NSs). The NSs expose (111) faces and are decorated by (Co, Ni)WO4 nanoparticles. DFT calculations reveal that Co and Ni atoms on the (111) surface of N/W co-doped NSs are more likely to adsorb OH-, while W atoms are more favorable to adsorb Cl-. Secondly, the lattice distortion and multi-crystal phases of NSs are triggered by doped W atoms, and the evacuation of 5d electrons makes W atoms as donor centers, leading to enhanced catalytic activity of CoNi atoms and corrosion resistance to Cl-. Furthermore, the N atoms expand the valence band of CoNiOx and elevate the conduction band of (Co, Ni)WO4, facilitating more electrons to participate in PEC reaction and the realization of seawater full-splitting. Resultantly, the N/W co-doped (Co, Ni, W)OxNy/WO3 hetero-NRs (HNRs) demonstrate a PEC current density about 0.35 mA/cm2 at 1.23 VRHE with durability over 100 hours in seawater. This work provides a practical strategy towards the durable PEC anode for seawater splitting.

Control interfacial charge transfer behavior by creating surface defects on structure unit of heterojunction to drive carrier separation for enhancing photocatalytic CO2 reduction

Controlling interfacial charge transfer behavior of heterojunction is an arduous issue to efficiently drive separation of photogenerated carriers for improving the photocatalytic activity. Herein, the interface charge transfer behavior is effectively controlled by fabricating an unparalleled VO-NiWO4/PCN heterojunction that is prepared by encapsulating NiWO4 nanoparticles rich in surface oxygen vacancies (VO-NiWO4) in the mesoporous polymeric carbon nitride (PCN) nanosheets. Experimental and theoretical investigations show that, differing with the traditional p-n junction, the direction of built-in electric field between p-type NiWO4 and n-type PCN is reversed interestingly. The strongly codirectional built-in electric field is also produced between the surface defect region and inside of VO-NiWO4 besides in the space charge region, the dual drive effect of which forcefully propels interface charge transfer through triggering Z-Scheme mechanism, thus significantly improving the separation efficiency of photogenerated carriers. Moreover, the unique mesoporous encapsulation structure of VO-NiWO4/PCN heterostructure can not only afford the confinement effect to improve the reaction kinetics and specificity in the CO2 reduction to CO, but also significantly reduce mass transfer resistance of molecular diffusion towards the reaction sites. Therefore, the VO-NiWO4/PCN heterostructure demonstrates the preeminent activity, stability and reusability for photocatalytic CO2 reduction to CO reaction. The average evolution rate of CO over the optimal 10 %-VO-NiWO4/PCN composite reaches around 2.5 and 1.8 times higher than that of individual PCN and VO-NiWO4, respectively. This work contributes a fresh design approach of interface structure in the heterojunction to control charge transfer behaviors and thus improve the photocatalytic performance.

Hierarchical core-shell electrode with rGO wrapped NiWO4 nanowire arrays on Ni foam for high-performance asymmetric supercapacitors

This paper presents a novel class of hierarchical core-shell nanowire arrays (NWAs) that may greatly enhance the electrochemical storage of energy capabilities of supercapacitors. These NWAs consist of rGO sheets surrounding a NiWO4 nanowire core. The average surface area of NiWO4 nanoparticles was 105.7 m2/g, and their sizes ranged from 20 to 100 nm. The NWO/rGO composite has an impressive specific capacitance of up to 1156 F g−1 at 1 A g−1 current density. The synergistic impact of NiWO4 and rGO, which offer conducting channels and active sites, is responsible for the NWO/rGO electrode's significantly improved capacitive performance. This hybrid electrode has a lot of promise for use in energy storage devices since the cyclic stability tests showed that its starting values did not decline after 5000 cycles. In a three-electrode system, the NiWO4/rGO electrode provides more energy density compared to the NiWO4 electrode because to a boost in specific capacitance and a wider potential window (1 V for nanocomposite NiWO4/rGO vs. 0.6 V for NiWO4). Electrodes made of a nanocomposite of NiWO4 and rGO are used to construct a symmetric capacitor. Both the asymmetric and symmetric capacitors function similarly when driven within a 1.5 V potential region. On top of that, the device achieved a power density of 932 W kg−1 and an energy density of 42 Wh kg−1.

Boosting the photocatalytic hydrogen generation: The multifunctional role of NiWO4 in NiS2/NiWO4/ZnIn2S4 hollow microsphere

As a promising metal sulfide co-catalyst, nickel disulfide (NiS2) has become extremely attractive for cost-effectiveness and efficiency during the photocatalytic activity of hydrogen evolution reaction (HER). However, the strong bonding strength of S-Hads poses a challenge in desorbing H atoms from the active S-site, hindering the photocatalytic hydrogen evolution performance of NiS2. Intrinsically, accelerating the photoproduction electron transfer and promoting the release of more hydrogen protons from active adsorption water is essential for enhancing photocatalytic hydrogen evolution. Herein, we propose an interface modulation strategy for promoting photocatalytic performance: fabricating amorphous NiWO4 nanoparticles modified on NiS2 cocatalysts to construct a NiS2/NiWO4/ZnIn2S4 hollow microsphere photocatalyst. The close contact arrangement between NiS2/NiWO4 microspheres and ZnIn2S4 nanosheets undeniably enhances charge separation of carriers. Meanwhile, the amorphous NiWO4 interlayer functions excellently in conductivity, as an “electron bridge,” for accelerating charge carrier transfer. Significantly, amorphous NiWO4 strongly interacts electronically with NiS2, reducing the local electron density of Ni and S atoms. This promotes the adsorption of water by Ni sites and optimizes of adsorption/desorption of hydrogen atoms at the adjacent S sites where S-Hads are weakened. The hierarchical ZnIn2S4/NiWO4/NiS2 photocatalyst remarkably boosts the hydrogen production rate. It was 11.919 mmol·g−1·h−1 compared to bare ZnIn2S4, and ZnIn2S4/NiS2 only showed 1.8 times increase, while ZnIn2S4/NiWO4/NiS2 increased by 12.5 times. The optimization of the active center in the study provides a beneficial strategy for designing efficient photocatalysts for water splitting with great potential for hydrogen evolution cocatalysts.

Enhanced visible-light-driven photocatalytic degradation of azo dyes by heteroatom-doped nickel tungstate nanoparticles

Abstract In this study, we conducted the hydrothermal synthesis of cobalt (Co)–doped NiWO4, resulting in the formation of Co–NiWO4 nanoparticles (NPs), followed by calcination at 550℃ for 12 h. Comprehensive analyses were performed to characterize the composition, structure, and morphology of the synthesized material. X-ray diffraction results confirmed the successful inclusion of Co in the NiWO4 lattice, with the presence of characteristic peaks of CoWO4. The crystallite size, determined using the Scherrer equation, was measured to be 22 nm. Using UV-Vis spectroscopy and Tauc’s equation, we calculated the band gap energy (E g) to be 3.75 eV for NiWO4 and 1.75 eV for Co–NiWO4. The potential application of the synthesized material as a photocatalyst was investigated for the degradation of the diazo dye Congo red (CR). Under optimized reaction conditions, Co–NiWO4 NPs demonstrated outstanding efficiency, degrading a total of 95% of CR. The degradation kinetics were well-described by the Langmuir–Hinshelwood (L–H) kinetic model, indicating that photoabsorption played a crucial role in the rate-controlling step. These encouraging results suggest that Co–NiWO4 NPs hold promise as a viable option for addressing other pollutants in various applications.

Sonochemical synthesis of nickel tungstate (NiWO4) nanoparticles for dye degradation and electrochemical sensing of lead ions in environmental samples

Here we have synthesised Nickel Tungstate (NiWO4) nanoparticles via sonochemical method. The structural and morphological studies were examined using XRD, FTIR, UV–Vis, SEM and TEM analysis. XRD pattern confirms the monoclinic wolframite structure of NiWO4 nanoparticles. FTIR spectrum reveals that strong absorption peaks at 450 cm−1 to 1000 cm−1 for stretching and bending vibrational frequencies of the Ni–W-O peaks in NiWO4. UV–Vis spectrum shows maximum intensity peak at ∼ 473 nm corresponding to the band gap of 3.0 eV. The SEM and TEM images show irregular shapes of nanoparticles. BET analysis shows a surface area 31.811 m2/g for NiWO4 nanomaterials. Methylene Blue (MB) and Rhodamine B (RhB) dyes were used as model pollutants for the analysis of photocatalytic activity under UV and visible light irradiations and it has proved as a fine photocatalyst. The electrochemical activity of the samples was studied by cyclic voltammetry (CV) and Electrochemical Impedance spectroscopy (EIS) in 1 M KOH aqueous electrolyte. EIS measurements showed a reduction in the charge transfer resistance in acidic electrolyte. Modified carbon paste electrode employing NiWO4 nanoparticles has sensed lead in alkaline electrolyte. The electrode displayed high sensitivity for lead detection under varying concentrations. These results confirm that the NiWO4 nanoparticles are promising electrode material for sensing lead with high electrode reversibility.

Engineering of direct Z-scheme ZnIn2S4/NiWO4 heterojunction with boosted photocatalytic hydrogen production

Exploring efficient and robust photocatalysts for solar hydrogen generation from water reduction is great significant in solving the energy shortage and environment contamination simultaneously. Herein, benefiting from the matchable energy band structures and band bending, the direct Z-scheme ZnIn2S4/NiWO4 heterojunctions were successfully constructed by anchoring p-type NiWO4 nanoparticles onto n-type ZnIn2S4 nanosheets through a facile sonochemical route. By carefully regulating the interfacial structure, the optimized ZnIn2S4/NiWO4 heterostructure without any cocatalyst displays excellent stability and remarkably improved photocatalytic hydrogen evolution activity (16.3 mmol∙g−1∙h−1), more 3.57-folds increment than bare ZnIn2S4 photocatalyst. Mechanistic characterizations demonstrate that the dramatically boosted photocatalytic performance mainly results from the constructed Z-scheme heterostructure and intimately interfacial contact between ZnIn2S4 and NiWO4, which results in the valid interfacial charge transfer channels, powerful redox potential and reduced hydrogen evolution energy barrier, as confirmed by the joint analysis of electron spin resonance (ESR) and photoelectrochemical measurements. More importantly, the photoinduced holes of ZnIn2S4 are rapidly and effectively consumed in the unique Z-scheme charge transfer channels, which greatly favors the suppression of the photocorrosion caused by insufficient hole extraction during the photocatalytic reaction, thereby promoting the overall stability and reusability of the ZnIn2S4/NiWO4 composite photocatalyst. This study paves the way for constructing other Z-scheme nano-heterostructure consisting of p-type and n-type semiconductors with efficient photoactivity and robust stability for energy and environmental applications.

Electronic redistribution over the active sites of NiWO4-NiO induces collegial enhancement in hydrogen evolution reaction in alkaline medium

The activity-enhancement of a new-generation catalyst focuses on the collegial approach among specific solids which exploit the mutual coactions of these materials for HER applications. Strategic manipulation of these solid interfaces typically reveals unique electronic states different from their pure phases, thus, providing a potential passage to create catalysts with excellent activity and stability. Herein, the formation of the NiWO4-NiO interface has been designed and synthesized via a three-step method. This strategy enhances the chance of the formation of abundant heterointerfaces due to the fine distribution of NiWO4 nanoparticles over Ni(OH)2 sheets. NiWO4-NiO has superior HER activity in an alkaline (1 M KOH) electrolyte with modest overpotentials of 68 mV at 10 mA cm−2 current density. The catalyst is highly stable in an alkaline medium and negligible change was observed in the current density even after 100 h of continuous operation. This study explores a unique method for high-performance hydrogen generation by constructing transition metal-oxides heterojunction. The XPS studies reveal an electronic redistribution driven by charge transfer through the NiWO4-NiO interface. The density functional theory (DFT) calculations show that the NiWO4-NiO exhibits a Pt-like activity with the hydrogen Gibbs free energy (ΔGH*) value of 0.06 eV compared to the Pt(ΔGH* = −0.02 eV).

Mesoporous NiWO4@rGO nanoparticles as anode material for lithium-ion battery

ABSTRACT Herein, we have tried to explore the charge storage properties of mesoporous NiWO4 as an anode in lithium-ion batteries (LIB). A one pot-solvothermal synthesis is used to tweak the properties of mesoporous NiWO4 nanoparticles with reduced graphene oxide (rGO) for the first time and explored the LIB anode applications. Materials are well characterised using structural and morphological characterisations to corroborate the relation between the electrochemical properties and the graphene addition. At 100 mA g−1, the NiWO4@rGO (NWZC) exhibits initial discharge capacity of 1439 mAh g−1, which is more than that of NiWO4 (NWZ). Both NWZ and NWZC display initial coloumbic efficiency of 91.65% and 62.1%. After 500 cycles, the coloumbic efficiency of the NWZ and NWZC is above 99%. The improved lithium-ion storage characteristics of the NWZC may be from the synergetic effect between NiWO4 and r-GO.

La-doped NiWO4 coupled with reduced graphene oxide for effective electrochemical determination of diphenylamine.

Diphenylamine (DPA) is a harmful pesticide widely used to control post-harvest scald of fruits. In this study, rapid and sensitive determination of DPA was realized by the development of an effective electrochemical sensor, which was fabricated by coupling La-doped NiWO4 nanoparticles (La/NiWO4) with reduced graphene oxide (rGO), and the obtained rGO/La/NiWO4 nanocomposite was modified on glassy carbon electrodes (GCEs). The morphologies, structures and compositions were well characterized, and the effects of La doping and the introduction of rGO on the crystal structure and electrochemical performance were discussed. The incorporation of both La and rGO was found to enhance the active surface area and improve conductivity, resulting in the enhanced electrocatalytic performance of rGO/La/NiWO4/GCE, including a wide linear range (0.01-500 μM), a low detection limit (0.0058 μM) and high sensitivity (1.778 μA μM-1 cm-2). The fabricated sensor was further used for DPA detection in fresh apple extract to evaluate its practicality and demonstrated excellent recoveries ranging from 99.52 to 104.70%.

Asymmetrical zinc phthalocyanine conjugated to various nanomaterials for applications in phototransformation of organic pollutants and photoinactivation of bacteria

Zinc phthalocyanine (ZnPc) complexes are linked to metallic nanoparticles covalently via amide and ester bonds. The photocatalytic activity of the conjugates of ZnPc complexes with NiWO4, Ag2WO4, CoWO4 and Ag-Fe3O4 nanoparticles are evaluated for photodegradation of methylene blue, tetracycline, and dibenzothiophene. The photocatalytic efficiencies of the prepared phthalocyanine complexes increased in the presence of nanoparticles. This work also reports on the photodynamic antimicrobial chemotherapy activity of these materials against Staphylococcus aureus (S. aureus) bacteria. The results indicate that Ag2WO4 based nanoconjugates exhibit high antimicrobial activity with higher log reduction compared to NiWO4, CoWO4 and Ag-Fe3O4 based materials.

A robust octahedral NiCoOxSy core-shell structure decorated with NiWO4 nanoparticles for enhanced electrocatalytic hydrogen evolution reaction

Electrocatalytic hydrogen evolution reaction by water splitting is deemed to a clean and efficient approach for greener energy. The intensive pursuit of cost-effective and stable electrocatalysts for HER is quite imperative and challenging. Herein, a typical core-shell NiWO4@NiCoOxSy/NCF nano-architecture consisted of NiCoOxSy/NCF octahedrons and NiWO4 nanoparticles on nickel-cobalt foam is synthesized, and the NiWO4@NiCoOxSy/NCF requires quite small overpotential of 85 mV to afford current density of 10 mA cm−2 for HER in 1 M KOH, respectively, while NiCoOxSy/NCF shows the overpotential of 132 mV at the current density of 10 mA cm−2 in 0.5 M H2SO4. Moreover, they still present good durability with continuous operation of 72 h in alkaline and acidic electrolytes, outperforming most of the non-noble bimetallic oxides or sulfides electrocatalysts. The prominent performance benefits from NiWO4@NiCoOxSy/NCF takes advantages of component respective strengths such as interfacial cooperative effect, strong electrical connection and fast electron transfer, the highly exposed surface area, in situ surface reconstruction. The work provides a new prospect toward the controlled design and rational fabrication of multicomponent hierarchical core-shell structure electrocatalyst in high-performance flexible electrochemical hydrogen production.

Intrinsic Lability of NiMoO4 to Excel the Oxygen Evolution Reaction.

Nickel-based bimetallic oxides such as NiMoO4 and NiWO4, when deposited on the electrode substrate, show remarkable activity toward the electrocatalytic oxygen evolution reaction (OER). The stability of such nanostructures is nevertheless speculative, and catalytically active species have been less explored. Herein, NiMoO4 nanorods and NiWO4 nanoparticles are prepared via a solvothermal route and deposited on nickel foam (NF) (NiMoO4/NF and NiWO4/NF). After ensuring the chemical and structural integrity of the catalysts on electrodes, an OER study has been performed in the alkaline medium. After a few cyclic voltammetry (CV) cycles within the potential window of 1.0-1.9 V (vs reversible hydrogen electrode (RHE)), ex situ Raman analysis of the electrodes infers the formation of NiO(OH)ED (ED: electrochemically derived) from NiMoO4 precatalyst, while NiWO4 remains stable. A controlled study, stirring of NiMoO4/NF in 1 M KOH without applied potential, confirms that NiMoO4 hydrolyzes to the isolable NiO, which under a potential bias converts into NiO(OH)ED. Perhaps the more ionic character of the Ni-O-Mo bond in the NiMoO4 compared to the Ni-O-W bond in NiWO4 causes the transformation of NiMoO4 into NiO(OH)ED. A comparison of the OER performance of electrochemically derived NiO(OH)ED, NiWO4, ex-situ-prepared Ni(OH)2, and NiO(OH) confirmed that in-situ-prepared NiO(OH)ED remained superior with a substantial potential of 238 (±6) mV at 20 mA cm-2. The notable electrochemical performance of NiO(OH)ED can be attributed to its low Tafel slope value (26 mV dec-1), high double-layer capacitance (Cdl, 1.21 mF cm-2), and a low charge-transfer resistance (Rct, 1.76 Ω). The NiO(OH)ED/NF can further be fabricated as a durable OER anode to deliver a high current density of 25-100 mA cm-2. Post-characterization of the anode proves the structural integrity of NiO(OH)ED even after 12 h of chronoamperometry at 1.595 V (vs reversible hydrogen electrode (RHE)). The NiO(OH)ED/NF can be a compatible anode to construct an overall water splitting (OWS) electrolyzer that can operate at a cell potential of 1.64 V to reach a current density of 10 mA cm-2. Similar to that on NF, NiMoO4 deposited on iron foam (IF) and carbon cloth (CC) also electrochemically converts into NiO(OH) to perform a similar OER activity. This work understandably demonstrates monoclinic NiMoO4 to be an inherently unstable electro(pre)catalyst, and its structural evolution to polycrystalline NiO(OH)ED succeeding the NiO phase is intrinsic to its superior activity.

Fabrication and characterization of mesoporous guar gum/NiWO4 nanocomposite for efficient adsorption of phloxine B and crystal violet from aqueous solution and evaluation of its antioxidant activity

Guar gum/nickel tungstate (GG/NiWO4) nanocomposite is prepared using simple and cost-effective sol-gel technique, while NiWO4 nanoparticles are formed by co-precipitation method. The nanocomposite is characterized by FTIR, XRD, BET, SEM-EDX and TEM techniques. The effectivity of GG/NiWO4 nanocomposite is investigated for the sequestration of phloxine B (PB) and crystal violet (CV) from wastewater. The effect of dose, agitation time, initial solution pH, and initial dyes concentration is appraised. The adsorption isotherm, kinetics and thermodynamic parameters are also studied. Langmuir isotherm and pseudo-second order models are best fitted to the equilibrium data. The thermodynamic parameters confirm that adsorption is spontaneous, exothermic and entropy-driven. An excellent desorption of PB and CV from the loaded adsorbent is acquired by utilizing either ethanol or acetone with a desorption ability in the range of 57.60%–91%. The antioxidant activities of synthesized nanocomposite are also studied.

Facile hydrothermal synthesis of nickel tungstate (NiWO4) nanostructures with pronounced supercapacitor and electrochemical sensing activities

Herein, we designed chain-like, round-shaped nickel tungstate (NiWO4) nanostructures by a simple hydrothermal method. The size of NiWO4 nanoparticles was between 20 and 100 nm and the average surface area was 101.4827 m2/g. Synthesized nanomaterial was investigated for electrochemical supercapacitor studies and charge–discharge capacity studies which demonstrated the enhanced specific capacitance. Results elaborate that NiWO4 synthesized at 180 °C and calcinated at 700 °C show enhanced specific capacitance 1524 F/g at a current density of 0.5 A/g. A maximum energy density of 32.27 WhKg−1 was achieved at a power density of 2206 Wkg−1. Furthermore, the successfully assembled supercapacitor also showed the largest charge/discharge time as 1353 s, corresponding to a current density of 0.5 A/g. Besides, NiWO4 nanostructures depicted promising electrochemical sensing capabilities when deposited on glassy carbon electrodes for the detection of ascorbic acid. The NiWO4 modified electrode showed excellent sensitivity for ascorbic acid with a limit of detection of 2.37 mM and 0.38 mM for cvp1 and cvp2, respectively. Furthermore, the electrochemical behavior of NiWO4 modified GCE for ascorbic acid was inquired in different electrolytes and the highest intensity was observed in LiSO4 electrolyte. Based on these findings, the present work might generate new intuition for the synthesis of different combinations of transition metal oxide nanostructures and their applications as supercapacitors and electrochemical sensors.

Investigation on the structural, morphological and electrochemical properties of nickel tungstate for energy storage application

We investigate the electrochemical properties of NiWO4 nanoparticles (NPs) were synthesized by simple hydrothermal route. The crystallographic structures, morphology and elemental compositions of the prepared NiWO4 were characterised by different spectroscopic techniques such as Scanning Electron microscopy, X- ray Diffraction and Energy dispersive X- ray Spectrum. The surface morphology of the prepared sample was analyzed by scanning electron microscope (SEM). The electrochemical studies were probed by using Cyclic Voltammetry (CV), charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS).

Influence of Bi3+ doping on structural, optical and photocatalytic degradation properties of NiWO4 nanocrystals

Pristine and Bi3+doped NiWO4 nanoparticles are synthesized by direct chemical precipitation method. The structural and optical properties are investigated using various characterization techniques. Optical absorption studies confirm dual direct-indirect bandgap nature of pure and Bi3+ doped NiWO4 nanoparticles. Doping with Bi3+ ion modifies the structural and optical parameters of NiWO4 sample. These variations in parameters influence the luminescence and photocatalytic properties of NiWO4 nanoparticles. The lowest doping concentration of Bi3+ leads to high PL emission and this property can be used in luminescence applications. The higher concentration of Bi3+ ions leads to the quenching of PL. The sample with the highest dopant concentration shows the lowest PL intensity and improved photocatalytic activity. Indirect chemical probe method reveals that OH.is the main active species involved in the photocatalytic decolouration of dyes. The degradation of dyes follows pseudo-first-order kinetics. Current work constitutes the first report on the effect of Bi3+ doping on the structural and optical properties, and photocatalytic activity of NiWO4 nanoparticles.

Ultrasonic-assisted synthesis of nickel tungstate nanoparticles on poly (3,4-ethylene dioxythiophene):poly (4-styrene sulfonate) for the effective electrochemical detection of caffeic acid

Herein, the ultrasonic-assisted synthesis of NiWO4 nanoparticles on poly(3,4‐ethylenedioxythiophene)–polystyrenesulfonate (PEDOT:PSS) for the electrochemical determination of caffeic acid (CFA) was investigated systematically. The NiWO4 nanoparticles and NiWO4@PEDOT:PSSx nanocomposite were synthesised through high-intensity ultrasonication in a bath sonicator. The as-prepared materials distinct nature was evaluated using electron microscopic and spectroscopic analysis, and the electrocatalytic properties of the sensor materials were determined through cyclic voltammetry (CV) and linear sweep voltammetry (LSV). CV examination indicated that the enhanced redox behaviour of CFA at a low potential is attributed to the incorporation of PEDOT:PSS into the NiWO4@PEDOT/PSS nanocomposite and their synergistic effects. The NiWO4@PEDOT:PSS sensors exhibited a low detection limit and high sensitivity of 74 nM and 969.49 μA mM−1 cm−2 towards CFA in LSV. Overall, the proposed sensor exhibited excellent analytical performance and uncompromised essential sensor features, such as selectivity, stability, repeatability and reproducibility. The NiWO4@PEDOT:PSS sensors have good practical compatibility in CFA detection in commercial coffee/red wine samples and are thus potential practical sensors.

NiWO4-induced partial oxidation of MXene for photo-electrochemical detection of prostate-specific antigen

MXene-based hybrid composites are gaining substantial attention due to their impressive chemical and electronic characteristics. Herein, an in-situ engineered heterojunction is constructed using partially-oxidised Ti3C2Tx sheets and photo-active NiWO4 nanoparticles (NPs). The NiWO4 NPs were used to induce partial surface oxidation of Ti3C2Tx, resulting in the formation of a Ti3C2Tx-TiO2/NiWO4 hybrid composite (MX-NiWO4). The electrocatalytic and photo-electrochemical (PEC) characteristics of MX-NiWO4 were studied in reference to the reduced graphene oxide-NiWO4 (rGO-NiWO4) and H2O2-treated Ti3C2Tx (MX-H2O2) hybrids. The MX-NiWO4, based on its in-situ driven configuration, constructed an ideal interfacial arrangement for the electrocatalytic mechanism-based PEC immuno-sensing of prostate-specific antigens (PSA). The developed PEC biosensor was capable of detecting PSA, over a wide detection range of 1.2 fg.mL−1 to 0.18 mg.mL−1, with a detection limit of 0.15 fg.mL-1. The synergic integration of Ti3C2Tx with photo-active NiWO4 offers a superior signal response and practical applicability when used for the quantification of PSA from human saliva samples, anticipating the hybrid’s promising future in clinical detection.

Effect of Bi3+ substitution on structural and electrical properties of polycrystalline NiWO4 nanoparticles

Pristine- and Bi3+-doped NiWO4 nanoparticles are synthesized by direct chemical precipitation. The structural properties are investigated using various characterization techniques. The electrical properties of pure and Bi3+-doped NiWO4 samples are analysed with the help of dielectric permittivity, dissipation factor, impedance and electric modulus. Nyquist plots along with the equivalent circuits are used to analyse the relaxation and conduction mechanism of pure and Bi-doped NiWO4. Doping of Bi3+ ion changes the structural and electrical properties of NiWO4 samples. With Bi3+ doping, the conductivity of NiWO4 is increased along with variation in the conduction mechanism. Current work constitutes the first report on the study of electrical properties of Bi3+-doped NiWO4 nanoparticles.