Photoelectrochemical Response Research Articles

Correlating activities and defects in (photo)electrocatalysts using in-situ multi-modal microscopic imaging

Photo(electro)catalysts use sunlight to drive chemical reactions such as water splitting. A major factor limiting photocatalyst development is physicochemical heterogeneity which leads to spatially dependent reactivity. To link structure and function in such systems, simultaneous probing of the electrochemical environment at microscopic length scales and a broad range of timescales (ns to s) is required. Here, we address this challenge by developing and applying in-situ (optical) microscopies to map and correlate local electrochemical activity, with hole lifetimes, oxygen vacancy concentrations and photoelectrode crystal structure. Using this multi-modal approach, we study prototypical hematite (α-Fe2O3) photoelectrodes. We demonstrate that regions of α-Fe2O3, adjacent to microstructural cracks have a better photoelectrochemical response and reduced back electron recombination due to an optimal oxygen vacancy concentration, with the film thickness and extended light exposure also influencing local activity. Our work highlights the importance of microscopic mapping to understand activity, in even seemingly homogeneous photoelectrodes.

Surface plasmonic hot hole driven Ag2S/Au/Al2O3 photocathode for enhanced photoelectrochemical water splitting performance

Herein, Ag2S/Au/Al2O3 photoelectrode was fabricated for superior photoelectrochemical (PEC) water splitting response. The working electrodes were deposited using the glancing angle deposition (GLAD) method followed by RF sputtering and atomic layer deposition (ALD). The as-prepared Ag2S/Au/Al2O3 samples revealed a higher photocurrent density of 2.50 mA/cm2 (at 0.95 V Ag/AgCl) as compared to bare Ag2S (1.70 mA/cm2) with a corresponding less charge transfer resistance at the semiconducting interface. The superior PEC response may be ascribed to the synergic effect of plasmonic Au nanoparticles and the tilted Ag2S nanorods. The plasmonic effect of Au nanoparticles increases the visible-light response of Ag2S as well as provides the hot holes to enhance the photocurrent density. In addition, the increased trapping of light due to the tilted architecture of Ag2S nanorods resulted in an effective absorption of light. The theoretical simulations based on finite difference time domain (FDTD) were also performed to explore the distribution of the electric-field intensity and optical trapping of light between the nanorods of Ag2S and Ag2S/Au. The experimental and theoretical results show a deeper insight into the role of plasmonic nanostructures decorated Ag2S nanorods and shed light on designing hybrid hot hole harvesting semiconductor nanostructures for the next generation photoelectrodes.

Improved photoelectrochemical performance of tungsten-catalyzed graphene nanoplatelet electrodes prepared by hot-wire chemical vapor deposition at low substrate temperatures

The current increase in demand for graphene in various energy applications such as electrode materials for supercapacitors, batteries, thermoelectric, and hydrogen production via water-splitting, the production of high-quality graphene, considering its fascinating physical and electrical properties, high-yield, and large-area has becoming more challenging at the research and development level. Therefore, in this work, graphene nanoplatelets (GNPs) were directly grown on tungsten nanoparticle (W NP)-coated p-type crystalline silicon and quartz substrates using hot-wire chemical vapor deposition at low substrate temperatures (<500 °C). Prior to the GNP deposition, a plasma process was employed to induce the formation of W NPs, which act as a metal catalyst for facilitating the growth of large-area and multi-layer GNPs. The W NPs were formed at substrate temperatures ranging from 250 to 550 °C, with the largest graphene sheet was grown at 450 °C. Higher substrate temperatures promote the growth of high-quality graphene layers with high intensities of G (IG) and 2D bands (I2D), and high I2D/IG ratio values. The GNP photoelectrode prepared at 450 °C demonstrated better photoelectrochemical responses with the highest photocurrent density of 1.65 mA/cm2 at 1.5 VAg/AgCl, the lowest charge transfer resistance (14.0 kΩ), and the highest donor density (2.57 × 10 28 cm−3) compared to the tungsten carbide thin film and W NP electrodes prepared at the same temperature. The effects of substrate temperature on the optical, structural, and photoelectrochemical properties of the as-grown GNPs are discussed.

Bulk and interface engineering with the combined addition of Na+ and E5+ (E = Nb5+, Ta5+) in the design of hematite photoanodes

In this letter, the synergistic effects of multiple element modification through a single polymeric precursor solution in hematite-based photoanodes using Na/Nb and Na/Ta as dopants are evaluated. Linear sweep voltammetry curves showed that the photoelectrochemical response was improved after Na/Nb (or Ta) addition. In both circumstances, an anodic shift (∼200 mV) in the onset potential was noticeable due to surface states created after Nb5+/Ta5+ segregation. The energetic loss caused by Nb (and Ta) segregation was partially restituted by NiFeOx addition due to the passivation of surface states, acting as recombination centers created by pentavalent modifiers. These combined modifications brought a three and four-fold increase for Na0.1HemNb1.5 NiFeOx and Na0.1HemTa1.0NiFeOx respectively. Charge carrier dynamics analysis studied by intensity modulated photocurrent spectroscopy revealed that the PEC enhancement in both systems is mainly associated with improved charge separation efficiency.

Electronic Structures of Passive Film Formed on Ti and Cr in a Phosphate Buffer Solution of pH 7

The electronic structures, including the semiconductive properties, of the passive films formed on Cr and Ti in a phosphate buffer solution of pH 7 were evaluated using photoelectrochemical response, electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy (XPS). Based on the results, electronic band structure models of the passive films were proposed: the passive films on Cr consisted of an inner p-type oxide layer with a band gap energy, E g, of 3.6 eV and an outer p-type hydroxide layer with E g of 2.5 eV whereas those on Ti consisted of an inner n-type oxide layer with E g of 3.2 eV and an outer n-type hydroxide layer with E g of 2.5 eV. The type of semiconductor evaluated for the oxide and hydroxide layers was strongly supported by valence-band XPS, which can provide the energy difference between the Fermi energy of the underlying metal and the highest energy of the valence bands of the oxide and hydroxide layers in the passive films.

Optimization of Photoelectrochemical Response on TiO2 Nanotube Arrays Treated by H3PO4 and Mechanism Analysis of the Slowing Down Effect during Preparation.

The process control of anodization has been a hot topic for a long time. In this study, the addition of phosphoric acid to the traditional electrolyte changed the ion distribution on the reaction interface and the composition of the anion contamination layer so as to achieve the slowing down effect on anodization, the mechanism and theoretical model of which are also given in this paper. TiO2 is a common material in photoelectrocatalysis, but there are few studies on the photoelectrochemical performance of TiO2 nanotube arrays. The stability and rapidity of the photoelectrochemical response of TiO2 nanotube arrays prepared in phosphoric acid containing an electrolyte were effectively optimized in this study.

A coupled faradaic/electrostatic boosting strategy for decolorization of a refractory dye inside a dually-biased photoelectrochemical reactor: Time and energy saving

A green sustainable strategy for environmental remediation and treatment of dye-polluted water is the application/development of effective photoelectrochemical (PEC) reactors. Despite some recent progress in PEC systems, achieving a complete decolorization is still a challenging issue and often requires a long period of reactor operation. Herein, the authors address this interesting time/energy-related problem, demonstrating how without consuming extra electricity/chemicals, fabricating complex photoelectrodes, or changing the pH of medium, one can effortlessly promote the activity of a PEC reactor just by its coupling to a non-faradaic bias source. By applying this novel dually biased (faradaic/electrostatic) boosting strategy, we reveal that decolorization of methyl orange (a refractory dye pollutant) is significantly improved and the decolorization time (thereby energy consumption) is reduced by almost half in comparison to that of a conventional PEC reactor–operating under a single-bias (faradaic) condition. The reactor activity and its photoelectrochemical response are finally discussed in detail in terms of applied potential biases, semiconductor's band bending, open-circuit-potential displacement, electrostatic interaction and electrosorption of dye pollutant.

G-C3N4/Porphyrin-based graphdiyne (PDY) 2D/2D heterojunction for the ultrasensitive photoelectrochemical detection of microRNA-21

As an n-type semiconductor material with a wide band gap, g-C3N4 has been applied in the photoelectrochemical (PEC) sensing field, while the narrow absorption light range and tendency of electron-hole recombination significantly limit its practical applications. In this study, we developed a new g-C3N4/porphyrin-based graphdiyne (PDY) 2D/2D heterojunction photoelectric nanocomposites via in-situ growth of PDY on the g-C3N4 nanosheets. The introduction of PDY significantly enhances the light capture ability of g-C3N4 in terms of absorbance and the absorption range throughout the entire UV-Vis region. More importantly, the well-matched band structure between PDY and g-C3N4 inhibits the electron-hole recombination to improve the charge separation efficiency. In addition, such 2D/2D heterojunction has a short charge transfer distance and a large contact area, further promoting the interfacial charge transfer. As a result, the PEC response of g-C3N4/PDY is 2.54 times higher compared with that of g-C3N4, enabling the ‘turn on’ PEC determination of miRNA-21 according to the sandwich-type sensing strategy, and the linear range of 0.01 fM-100 pM with a limit of detection (LOD) of 0.005 fM was achieved. Due to the diversity of graphdiyne monomers, we envision that the g-C3N4/PDY 2D/2D heterojunction carrying different graphdiyne-based materials may exhibit great potential in PEC sensing, photocatalysis, and solar cells.

CdS quantum dots sensitized Ti-MOFs as high-performance photocathodic materials for immunoassay of alpha-fetoprotein based on Ag+ exchange strategy

Cathodic photoelectrochemical (PEC) analysis has drawn much attention because of its excellent anti-interference capability toward reductive substances in samples, but the development high-performance photocathodic materials is challenging. We report here CdS quantum dots (QDs) sensitized titanium-based metal–organic frameworks (Ti-MOFs) as high-performance photocathodic materials for ultrasensitive immunoassay of alpha-fetoprotein (AFP) based on Ag+ exchange strategy. Due to the excellent sensitization effect of CdS QDs, the photocathodic current of CdS QDs decorated MIL-125-NH2(Ti) is 25-fold that of MIL-125-NH2(Ti) alone. The photocathodic current of CdS/MIL-125-NH2(Ti) can be quenched after Ag+ exchange, because CdS is partially converted to Ag2S that serves as a charge-recombination center. Based on the PEC response of CdS/MIL-125-NH2(Ti) to Ag+, a cathodic PEC immunoassay platform is constructed for AFP detection by using CdS/MIL-125-NH2(Ti) as the photoactive material and Ag nanoparticles modified SiO2 nanospheres as labels. The linear range for AFP detection is from 1.0 × 10−4 to 1.0 × 102 ng mL−1, and the detection limit is 20 fg mL−1. The constructed PEC immunosensor is successfully used for detecting AFP in human serum samples. In this work, a novel and high-performance photoactive material is developed for cathodic PEC analysis, and a simple and effective PEC immunoassay platform for AFP detection is constructed based on Ag+ exchange strategy.

A photoelectrochemical aptasensing platform assembled at the heterojunction interface of Cu3BiS3 sensitized CuV2O6 for bisphenol A.

The interaction between the sensitive interfaces of photoelectrochemical (PEC) semiconductor nanomaterials and microscopic matter creates endless potential for the efficient detection of endocrine disruptor. Thiswork presents the development of a high-efficiency PEC aptasensor for bisphenol A (BPA) monitoring based on Cu3BiS3 sensitized CuV2O6 nanocomposites with exceptional visible-light PEC activity. We implemented the integration of Cu3BiS3 nanosheet photosensitizer to sensitize the CuV2O6 nanowire structure that was synthesized utilizing a facile hydrothermal approach. The band gap alignment between Cu3BiS3 and CuV2O6 facilitated enduring PEC response yielding an efficient interfacial structure. The surface of the CuV2O6/Cu3BiS3 electrode was modified with BPA aptamer, enabling specific binding with BPA and precise quantification of its content. The developed aptamer sensors possess a wide detection range of5.00 × 10-1 to 5.00 × 104 ng/mL, and a low detection limit of 1.60 × 10-1 ng/mL (at S/N = 3). After undergoing 20 testing cycles and enduring long-term storage, the sensor maintained its stability and showcased excellent repeatability and reproducibility. This study presents a promising methodology for the detection of BPA in environmental settings.

Wavelength-dependent photoelectrochemical response demonstrated by the determination of acetaminophen and rutin in differential molecularly imprinted polymers strategy

Herein, the excitation wavelength-dependent responses of the molecularly imprinted polymer (MIP) photoelectrochemical (PEC) sensors were investigated, using acetaminophen (AP), rutin (RT) and perfluorooctanoate (PFOA) as the model templates, pyrrole as functional monomer, CuInS2@ZnS/TiO2 NTs as the basic photoelectrode. With wavelength λ > 240 nm, the photocurrent of MIPPFOA enhanced at higher concentrations of PFOA. With increasing AP concentration, the photocurrents of MIPAP could decline with λ < 271 nm, not change at λ = 270 nm, or increase with λ > 270 nm. As RT concentration increased, the photocurrents of MIPRT could decrease (λ < 431 nm), not change (λ = 431 nm) or increase (λ > 431 nm). The PEC responses depend on the comprehensive interaction of two contrary mechanisms from the template molecules within the MIP membrane. The photocurrent is enhanced by the role of the electron donor for photo-generated holes but attenuated due to the steric hindrance effect and the excitation light intensity loss via absorption or scattering. The apparent molar absorption coefficient of AP and RT within MIP membranes are 9.1–19.4 folds of those measured from dilute solutions. By using a routine UV lamp as the light source, the photocurrents of MIPRT at 254 nm and MIPAP at 365 nm were used to determine RT and AP, with the detection limits of 5.3 and 16 nM, respectively. The interference from the non-specific adsorption of interferents on the surfaces of MIPAP and MIPRT was reduced by one order of magnitude via a differential strategy.

A label-free photoelectrochemical biosensor for silver ions based on Zn-Co doped C and CdS QD nanomaterials.

A sensitive photoelectrochemical (PEC) biosensor for silver ions (Ag+) was developed based on Zn-Co doped C and CdS quantum dot (CdS QD) nanomaterials. Hydrophobic modified sodium alginate (HMA), which could stabilize and improve the PEC performance of CdS QDs, was also used for the construction of PEC sensors. Especially, Zn-Co doped C, CdS QDs and HMA were sequentially modified onto an electrode surface via the drop-coating method, and a C base rich DNA strand was then immobilized onto the modified electrode. As the C base in DNA specifically recognized Ag+, it formed a C-Ag+-C complex in the presence of Ag+, which created a spatial steric hindrance, resulting in a reduced PEC response. The sensing platform is sensitive to Ag+ in the range of 10.0 fM to 0.10 μM, with a limit of detection of 3.99 fM. This work offers an ideal platform to determine trace heavy metal ions in environmental monitoring and bioanalysis.

Efficient sensitization of CdTe QDs towards PTCDA for sensitive photoelectrochemical Hg2+ assay.

Herein, a sensitive photoelectrochemical (PEC) biosensor was designed for the detection of mercury ions (Hg2+) on the basis of the efficient sensitization of cadmium telluride quantum dots (CdTe QDs) towards 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) and the significant quenching ability of a thymine-Hg2+-thymine (T-Hg2+-T) structure. The proposed CdTe QD/PTCDA sensitized structure was successfully constructed via continuous incubation of PTCDA and CdTe QDs on the glassy carbon electrode (GCE) interface, which embraced strong light absorption capacity and high carrier separation efficiency, giving rise to a remarkably improved initial photocurrent response. Notably, the PEC signal generated from the CdTe QD/PTCDA sensitized structure was almost fivefold higher than that of PTCDA owing to the efficient sensitization of CdTe QDs towards PTCDA. Once target Hg2+ ions were added, a T-rich S1 strand modified on the surface of 1-hexanethiol (HT)/S1/gold nanoparticles (Au NPs)/CdTe QDs/PTCDA/GCE immediately reacted with Hg2+ to produce multiple stable T-Hg2+-T structures. Therefore, the initial PEC signal would be considerably quenched by a high steric hindrance effect derived from the T-Hg2+-T structures. As a result, a quenched PEC response could achieve the detection of Hg2+ in concentrations ranging from 100 fM to 1000 nM. More importantly, the combination of the CdTe QDs/PTCDA sensitization structure and the T-Hg2+-T structure paves a promising pathway to developing a novel PEC biosensing platform for Hg2+ detection and also provides a favorable strategy for monitoring environmental pollution related to Hg2+.

CRISPR/Cas12a-Derived Photoelectrochemical Aptasensor Based on Au Nanoparticle-Attached CdS/UiO-66-NH2 Heterostructures for the Rapid and Sensitive Detection of Ochratoxin A.

The sensitive and accurate detection of ochratoxin A (OTA) is crucial for public health due to its high toxicity. Herein, using Au nanoparticle (NP)-attached CdS/UiO-66-NH2 heterostructures as photoactive materials, a photoelectrochemical (PEC) aptasensor was presented for the ultrasensitive assay of OTA based on a competitive displacement reaction triggering the trans-cleavage ability of CRISPR/Cas12a. In this sensing strategy, methylene blue-labeled single-stranded DNA (MB-ssDNA) was immobilized on the Au NPs/CdS/UiO-66-NH2 electrode to accelerate the separation of the photogenerated carrier, thus producing a significantly increased PEC response. In the presence of OTA, it specifically bound with the aptamer (Apt) and resulted in the release of the activation chain, triggering the trans-cleavage characteristics of CRISPR/Cas12a. MB-ssDNA was cut randomly on the electrode surface to convert the PEC signal from the "on" to the "off" state, thereby achieving a quantitative and accurate detection of OTA. The CRISPR/Cas12a-derived PEC aptasensor exhibited excellent sensitivity and specificity, with a linear range from 100 to 50 ng/mL and a detection limit of 38 fg/mL. Overall, the proposed aptasensor could provide a rapid, accurate, and sensitive method for the determination of OTA in actual samples.

Photocatalytic degradation of butyl benzyl phthalate by S-scheme Bi/Bi2O2CO3/Bi2S3 under simulated sunlight irradiation

As a kind of plasticizer, butyl benzyl phthalate (BBP) presents a serious hazard to the ecosystem. Therefore, there is a strong need for an effective technique to eliminate the risk of BBP. In this work, a new photocatalyst of Bi/Bi2O2CO3/Bi2S3 with an S-scheme heterojunction was synthesized using Bi(NO3)3 as the Bi source, Na2S as the S source, and DMF as the carbon source and reductant. Numerous techniques have been used to characterize Bi/Bi2O2CO3/Bi2S3, such as scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The improved photoactivity of Bi/Bi2O2CO3/Bi2S3 was evaluated by photoelectrochemical response, electrochemical impedance spectroscopy, photoluminescence, UV–Vis diffuse reflectance spectroscopy, and electrochemical Mott Schottky spectroscopy. The enhanced photocatalytic activity of this composite for BBP degradation under simulated sunlight irradiation could be attributed to the surface plasmon resonance effect of Bi metal and the heterojunction structure of Bi2O2CO3 and Bi2S3. The degradation rate of Bi/Bi2O2CO3/Bi2S3 was 85%, which was 4.52 and 1.52 times that of Bi2O2CO3 and Bi2S3, respectively. The prepared photocatalyst possessed good stability and reproducibility in eliminating BBP. The improved photocatalytic activity of Bi/Bi2O2CO3/Bi2S3 was demonstrated with the formation of an S-scheme heterojunction, and the degradation mechanism was discussed with a liquid chromatograph mass spectrometer.

Formation of the Heterojunction Based on Titania Modified with Ni and Ag Sulfide Via SILAR Method - Electrochemical and Photoelectrochemical Activity

The great interest of TiO2 nanotubes (TiNT) is justified by large surface area, high degree of ordering, facilitated charge transport along the nanotube, mechanical strength, strong UV absorption and light scattering due to the pore specific arrangement well as wide range of potential applications in solar cells, photocatalysis and sensors [1]. However, due to the wide energy band gap of TiO2 (3.2 eV) its photoactivity is limited and therefore titania based heterojunction are formed with the photoabsorber being active in the visible range [2]. In line with this strategy, we present electrochemical and photoelectrochemical activity of TiNT modified by NiS and AgS.The electrode is fabricated via electrochemical anodization of Ti foil, thermal annealing providing anatase phase and finally Successive Ionic Layer Adsorption and Reaction (SILAR) was carried out using silver, nickel and sulfur ions precursor and with different number of deposition cycles. The characteristic Ag-S, Ag-O and S-O peaks appearing on Raman spectra indicating successful SILAR modification. The cyclic voltammetry curves for TiNT, NiS/TiNT, AgS/TiNT and AgS/NiS/TiNT electrode were registered in 0.5 M Na2SO4 (Fig.1a). Peaks found on the anodic branch of the AgS/NiS/TiNT electrode at 0 V and +0.3 V vs. Ag/AgCl/0.1 M KCl are assigned to oxidation of Ag0 to Ag1+ and Ag1+ to Ag2+, respectively. When the scan went towards cathodic direction, peak located at +0.1 V and -0.1 V indicates reduction of Ag2+ to Ag1+ and Ag1+ to Ag0, respectively [3]. Furthermore, the linear voltammetry measurements performed under visible light illumination in 0.5 M Na2SO4 is presented in Fig.1b. The best photoactivity was reached for the AgS/NiS/TiNT electrode when only 5 deposition cycles for each metal precursor was applied. The photocurrent registered at +0.5 V reaches ca. 40 µA/cm2 which is 20 times higher than for pure TiNT.Summing up, modification of titania nanotubes by nickel and silver sulfides significantly enhanced material photoelectrochemical response under visible light. Moreover, it has been proved that this synergetic effect originated from the titania/metal sulphide heterojunction that can be achieved using SILAR method.Research is financed by National Science Centre (Poland): Grant no. 2020/39/I/ST5/01781[1] K. Siuzdak et al. RSC Advances, 5 (2015) 50379, DOI:10.1039/c5ra08407e[2] S. Chandrasekaran et al. Chemical Society Reviews, 48 (2019) 4178, DOI:10.1039/c8cs00664d[3] J.R.N. Santos et al. Electrocatalysis, 13 (2022) 713, DOI: 10.1007/s12678-022-00754-2 Figure 1

Incorporation of ZnIn2S4 semiconductors with S-vacancy engineered MoS2 nanosheets to develop sensitive photoelectrochemical aptasensor for aflatoxin B1 detection

Aflatoxin B1 (AFB1) has been categorized as group I potent carcinogen to human. Therefore, sensitive detection of AFB1 is of great significance for food safety. Here, a sensitive photoelectrochemical (PEC) aptasensor for AFB1 detection has been developed based on the incorporation of ZnIn2S4 semiconductors with S-vacancy engineered MoS2 (V-MoS2) nanosheets. V-MoS2 nanosheets were obtained by a mild H2O2-mediated chemical etching strategy with varying etching time. ZnIn2S4/V-MoS2 nanocomposites were prepared by a solvothermal method using V-MoS2 as one of the starting materials. Research demonstrated that the incorporation of ZnIn2S4 semiconductors with V-MoS2 could produce ZnIn2S4/V-MoS2 nanocomposites having a broader light absorption range and narrower energy bandgap, which help to generate a larger and highly stable PEC responses. The photocurrent intensity was 3.2 and 5.6 times greater than ZnIn2S4/MoS2 and ZnIn2S4, respectively. Based on the top performing ZnIn2S4/V-MoS2 nanocomposites and the specific aptamer, a PEC aptasensor was successfully constructed for AFB1 detection with a wide linear range of 0.05–50 ng/mL and a low detection limit of 17 pg/mL (S/N = 3). The significance of this work lied not only in representing substantive progress in food safety monitoring, but also in promoting the design of more efficient ZnIn2S4 or V-MoS2-related heterostructures for PEC sensors.

Formation of self-organized TiO2 nanotube arrays and its photoelectrochemical response

Formation of self-organized TiO2 nanotube arrays and its photoelectrochemical response

Flower like Ni doped BiVO4 composite with efficient visible light photocatalytic performance for the removal of Naproxen: A detailed mechanism and DFT study

BiVO4 and Ni doped BiVO4 (Ni-BiVO4) photocatalysts were synthesised by the co-precipitation method. BiVO4 and Ni-BiVO4 photocatalysts were characterized by various analytical techniques. PXRD studies of the BiVO4 and Ni-BiVO4 catalysts shows monoclinic-scheelite structure. Density functional theory calculations were carried out to predict the density of states and band gaps. The flower bunch is arrayed in a rod-like pattern on the HRTEM images, and the particle size was estimated using d-spacing and found to be in the range of 98-415 nm. Furthermore, the charge separation mechanism of photogenerated charge carriers of BiVO4 and Ni-BiVO4 photocatalysts were studied by photoelectrochemical response and impendence spectroscopy. The result shows that the Ni-BiVO4 photocatalyst possess the higher photocatalytic performance, and this can be attributed to the enhanced absorption of visible light, and lower recombination of electron and holes. Further, enhanced photocatalytic activity of Ni-BiVO4 photocatalyst was observed by addition of hydrogen peroxide (H2O2). The order of photocatalytic activity for the degradation of Naproxen under visible light: Ni-BiVO4 +H2O2 > Ni-BiVO4 > BiVO4 > Ni-BiVO4 + IPA. The investigation of degradation products was carried out utilising liquid chromatography mass spectroscopy coupled UV-visible absorption spectrum technique. Radical quenching is studied to reveal the substantial contribution of hydroxyl free radicals in the Ni-BiVO4 with H2O2 system.

Nickel depositing in TiO2 nanotube photoanode with promoted photoelectrochemical response

Nickel depositing in TiO2 nanotube photoanode with promoted photoelectrochemical response