Photoelectrochemical Water Splitting Activity Research Articles

In2S3 nanoparticles modify the porous Fe2V4O13 nanostructure photoanode to enhance charge separation efficiency and photoelectrochemical water splitting performance

In this study, we demonstrate for the first time a promising photoanode of Fe2V4O13/In2S3 (FVO/IS) nanoparticles (NPs) for photoelectrochemical (PEC) water splitting. Most importantly, this work presents the first application of X-ray photoelectron spectroscopy in tracking electron flow direction within FVO/IS to reveal the formation of heterojunction having the electron flow from IS to FVO. Mott-Schottky measurement confirms that the modification of IS NPs establishes the type II heterojunction between FVO and IS, favorable for the transport and separation of carriers. Spectral measurements of electrochemical impedance spectroscopy, photoluminescence and Bode diagram confirm the effective separation of carriers and the prolongation of the charge lifetime in the FVO/IS heterojunction photoanode. Moreover, the electrochemical measurements evidently demonstrate the substantial enhancement in the charge separation efficiency (ηseparation) and charge transfer efficiency (ηtransfer) of the photoanode, leading to significantly enhanced PEC water splitting capability. As a result, in contrast with the pure FVO NPs photoanode, the photocurrent density of the constructed FVO/IS NPs photoanode is increased by 27 times without bias. This study paves a new approach for boosting the PEC water splitting activity of FVO photoanodes by constructing heterostructures through modification with other semiconductors.

Killing two birds with one stone: Enhancing the photoelectrochemical water splitting activity and stability of BiVO4 by Fe ions association

Killing two birds with one stone: Enhancing the photoelectrochemical water splitting activity and stability of BiVO4 by Fe ions association

Long-Term Stability of Light-Induced Ti3+ Defects in TiO2 Nanotubes for Amplified Photoelectrochemical Water Splitting.

This study shows that the simple approach of keeping anodic TiO2 nanotubes at 70 °C in ethanol for 1 h results in improved photoelectrochemical water splitting activity due to initiation of crystallization in the material amplified by the light-induced formation of a Ti3+ -Vo states under UV 365 nm illumination. For the first time, the light-induced Ti3+ -Vo states are generated when oxygen is present in the reaction solution and are stable when in contact with air (oxygen) for a long time (two months). We confirmed here that the amorphous or nearly amorphous structure of titania supports the survival of Ti3+ species in contact with oxygen. It is also shown that the ethanol treatment substantially improves the morphology of the titania nanotube arrays, specifically, less surface cracking and surface purification from C- and F-based contamination from the electrolyte used for anodizing.

An Interface-cascading Silicon Photoanode with Strengthened Built-in Electric Field and Enriched Surface Oxygen Vacancies for Efficient Photoelectrochemical Water Splitting.

To promote interfacial charge transfer process and accelerate surface water oxidation reaction kinetics for photoelectrochemical (PEC) water splitting over n-type Silicon (n-Si) based photoanodes, herein, starting with surface stabilized n-Si/CoOx , a NiOx /NiFeOOH composite overlayer was coated by atomic layer deposition and spray coating to fabricate the multilayer structured n-Si/CoOx /NiOx /NiFeOOH photoanode. Encouragingly, the obtained n-Si/CoOx /NiOx /NiFeOOH photoanode exhibits much increased PEC activity for water splitting, with onset potential cathodically shifted to ~0.96 V vs. RHE and photocurrent density increased to 22.6 mA cm-2 at 1.23 V vs. RHE for OER, as compared to n-Si/CoOx , even significantly surpassing the counterpart n-Si/CoOx /NiOx /FeOOH and n-Si/CoOx /NiOx /NiOOH photoanodes. Photophysical and electrochemical characterizations evidence that the deposited CoOx /NiOx /NiFeOOH composite overlayer would create large band bending and strong built-in electric field at the introduced cascading interfaces, thereby producing a large photovoltage of 650 mV to efficiently accelerate charge transfer from the n-Si substrate to the electrolyte for water oxidation. Furthermore, the surface oxygen vacancy enriched NiFeOOH overlayer could effectively catalyze the water oxidation reaction by thermodynamically reducing the energy barrier of rate determining step for OER.

Unveiling the cutting-edge progress in boosting the photoelectrochemical water-splitting efficiency of BiVO4 photoanode with transition metal-based materials for sustainable hydrogen production

To address the significant depletion of fossil fuel reserves, hydrogen (H2) fuel has emerged as a promising alternative energy source due to its eco-friendly nature and impressive efficiency. Over the years, research efforts have led to the development of various methods for producing H2, with a particular focus on photoelectrochemical (PEC) water-splitting. Impressively, the interest in bismuth vanadate (BiVO4) photoanode has been a research focus lately ascribed to its photosensitive characteristic and high electron mobility. Moreover, doping of metals, defects engineering, morphology modification, and synthesis of heterojunction material strategies have been exercised to further improve its PEC water-splitting activity. Consequently, several reviews have been published on the PEC performance of BiVO4 modified with these strategies. However, to the best of our knowledge, there has been no comprehensive review specifically focusing on the impact of transition metal-based materials on the PEC performance of BiVO4. In this context, we present a critical review of the recent developments involving the modification of BiVO4 photoanode with transition metal-based materials for PEC water-splitting. Several transition metals such as nickel (Ni), cobalt (Co), iron (Fe), and tungsten (W) have been used in the recent development of BiVO4-based photoanodes. Surprisingly, all of the modified BiVO4 exhibited a substantial improvement in PEC activity with the photocurrent density at 1.23 VRHE reaching as high as 10.3 mA/cm2 has been reported in a previous study. Ultimately, this review highlights the promising potential of modified BiVO4 for the PEC water-splitting application.

Facile Fabrication of Indium-Doped TiO2 Via Anodization As Photoanodes for Photoelectrochemical Water Splitting Under Visible Light

Directionality of Nanostructured forms of TiO2 prepared through electrochemical anodization as photoanodes in photoelectrochemical (PEC) water splitting benefits the efficient e- and h+ separation. However, a large band gap hinders using such nanostructures in the presence of visible light. Doping with metals can be one of the strategic ways to reduce band gaps. In the present work, single-step anodization of titanium foils in the viscous electrolyte containing different concentrations of indium metal salt is used to fabricate Indium-doped TiO2 nanostructures. The anodization samples are annealed to obtain the photoactive anatase phase of TiO2. As prepared, Indium-doped TiO2 structures are characterized by field emission scanning electron microscope, X-ray diffraction, and UV-Vis light diffuse absorbance spectroscopy. PEC water splitting activity of Indium-doped TiO2 nanostructures is tested in 1 M KOH using a Xe-arc lamp equipped with an AM1.5 G filter under 1 sun. Indium doping enhances the photocurrent, photostability, and charge separation properties compared to the bared TiO2 nanostructures. This work shows that doping the optimum amount of Indium affects the PEC activity of the photoanodes through increased TiO2 lattice defects, and electrical conductivity.

The borophene quantum dots scaffolded TiO2 nanocomposite as an efficient photo electrocatalyst for water splitting application

Herein, we are scaffolding borophene quantum dots (BPQDs) on photoactive semiconductor nanomaterial such as TiO2 nanoparticle which shows enhanced photoelectrochemical (PEC) water splitting activity. The BPQDs are synthesized by sonochemical method and then scaffolded onto TiO2 nanoparticles by hydrothermal method. Further, the concentration of BPQDs on TiO2 nanoparticles is optimized for better photoelectrochemical water splitting application. The effective absorption edge is found to be less (2.51 eV) for 2.5 wt% BPQDs scaffolded TiO2 nanoparticles as studied by UV–Visible spectroscopic analysis. Transmission electron microscopic (TEM) images reveal the scaffolding of BPQDs of size (2–9) nm with TiO2 nanoparticles of having the size ∼25 nm. XRD results confirmed the anatase phase of TiO2 nanoparticles and b-rhombohedral boron structure for BPQDs. The FTIR and XPS results confirms the presence of boron functionalized groups in the nanocomposites. The photoluminescence (PL) spectroscopic results revealed the decrease in PL emission intensity for BPQDs/TiO2 nanocomposite indicating the decreased photogenerated charge carriers recombination time. The work function (ϕ) is found to be less for BPQDs/TiO2 nanocomposite signifying the easy release of electrons under the presence of visible light illumination. Further, BPQDs/TiO2 nanocomposite shows the improvement in photoelectrochemical (PEC) water splitting due to the synergistic effects of individual components.

Unprecedented iron-based photoelectrocatalysts@graphene foam composites as electrolyzing nanomaterials for water splitting in a neutral environment

Using nonprecious metal catalysts to efficiently produce large capacities of H2 and O2 from water splitting through the photoelectrolysis path is a crucial objective. The FeS2/α-Fe2O3 composite is first synthesized using thiourea under hydrothermal conditions and is subsequently combined with different weight ratios of graphene foam (GF; 6–20 %). The catalyst FeS2/α-Fe2O3@11 %GF demonstrates the highest photoelectrochemical water splitting activity at an excessive potential of 0.17 V, accomplishing a current density of 10 mA cm−2 and a Cdl of 2.14 mF cm−2 for HER, exceeding Pt/C results (0.53 V, 2.0 mF cm−2). OER, on the other hand, exhibits an overpotential of 0.18 V at 10 mA cm−2 and a low Tafel slope value of 77.9 mV dec−1, causing a very considerable rise in the reaction kinetics with a noticeably stable behavior. Total water splitting was achieved using the FeS2/α-Fe2O3@11 %GF || FeS2/α-Fe2O3@11 %GF electrolyzer with a small cell voltage of 1.63 V to produce 10 mA cm−2. Due to the significant interfacial effects produced by the well-integrated GF, boosted pore volume and surface area, abundance of accessible sites of activity, and growing Fe2+/Fe3+ ratio, which significantly improved electron transfer and electrolyte transport, the three-component system improved its ability to achieve efficient water splitting.

Insights into the structural, and functionality of RuO2/TiO2 and Ni(OH)2/RuO2/TiO2 for water splitting and dye degradation

Heterogeneous catalysis and the uniform interface are playing a vital role in environmental protection and are amenable to photoelectrochemical transformation reactions. Herein, a mixed metal oxide catalyst composed of RuO2 or RuO2/Ni(OH)2 supported on TiO2 is developed via the facile sol-gel method. Structural and morphological analyses confirm the presence of RuO2 and Ni(OH)2 beside the anatase phase in the composite catalysts . The band gap of TiO2 is tuned after contacting with RuO2 (2.35 eV) and the surface area is doubled. XPS shows the existence of a high level of defects and VSM demonstrates a ferromagnetic-like hysteresis loop for TiRu. A fast positron annihilation is observed of TiRu compared to TiO2 indicating smaller free volume defects in the composite powders. The oxidation tests of water display a high current density of 18.6 mA/cm2 and dimensional stability for the TiRu sample with negligible electroactivity for TiRuNi. On the other hand, the photoelectrochemical water splitting activity is found to be the lowest for the composite samples compared to TiO2. The photocatalytic efficiency is further examined via the removal of two industrial dyes (Dianix Blue and Indigo Carmine dyes) and the performance is correlated to the results obtained from Mott-Schottky.

A review of recent modification strategies of TiO2-based photoanodes for efficient photoelectrochemical water splitting performance

To address concerns about greenhouse gas emissions and sea level rise brought on by global climate change, hydrogen (H2) has the capacity to substitute fossil fuels as a carbon-free source of energy. The most reliable method of producing H2 is photoelectrochemical (PEC) water splitting, which uses water and solar as renewable energy sources. Titanium dioxide (TiO2) is one of the excellent semiconductors utilized as an effective photoanode in PEC water splitting due to its efficient light absorption, cost-effectiveness and excellent photostability. The primary emphasis of this review was on the various techniques used to modify TiO2-based photoanodes and presents a comprehensive overview of the latest progress made towards improving their effectiveness for PEC water splitting. It involves different preparation methods of TiO2-based photoanodes such as hydrothermal, chemical vapor, physical vapor, electrochemical deposition, and other methods which plays a crucial role in determining their structural, morphological, and surface properties. These properties, in turn, influence the light absorption, charge transport, and PEC water splitting activity, ultimately affecting the effectiveness and efficiency of PEC water splitting. Furthermore, elaboration on the outcomes of modification on the physical-chemical-optical features of TiO2-based photoanodes that result from preparation methods is included in this review. The review provides valuable understanding regarding the creation and advancement of high-performing TiO2-based photoanodes in the sustainable energy generation.

Y2O3 electrodeposited TiO2 nanotube arrays as photoanode for enhanced photoelectrochemical water splitting

Y2O3 deposited TiO2 nanotubes (Y-TNTs) are investigated as photoanodes for efficient photoelectrochemical water splitting. Y2O3 is electrodeposited on TiO2 nanotubes for 5–15 min. The physicochemical and optical properties of Y-TNTs reveal that Y2O3 anchored on the TNTs enhances the visible light absorption. The Y-TNTs show good photocurrent response compared to pristine TNTs. Y2O3 deposition for 10 min on TNTs produces highest photocurrent of 609 μA cm−2 at 1.23 VRHE. Presence of Y2O3 increases the lifetime of the charge carriers as revealed by the Nyquist plot analysis and Mott-Schottky analysis. Y-TNTs-10 min sample shows 2.75 times higher photoconversion efficiency compared to pristine TNTs. Computational analysis shows that Y–TiO2 has negative free energy of adsorption for OER intermediates as compared to bare TiO2 which has positive values. The rare earth metal electrodeposition on TiO2 nanotubes is another approach to improve the photoelectrochemical water splitting activity without distorting the nanotube structure.

Unveiling the high activity origin of NiFe catalysts decorated Ta3N5 photoanodes for oxygen evolution reaction

Bimetallic NiFe catalysts could effectively promote the photoelectrochemical (PEC) water splitting activities of Ta3N5 photoanodes, while exploring the intrinsic activity origin is crucial for constructing highly efficient solar-energy conversion systems. Herein, we demonstrate a simple impregnation strategy for rational deposition of NiFe catalysts nanolayers on Ta3N5 nanotube photoanodes, which achieved a superior photocurrent density of 11.2 mA cm−2 at 1.23 V versus the reversible hydrogen electrode (RHE) accompanied by a low onset potential (0.3 VRHE). More importantly, systematic studies reveal that the preferred deposition of Fe catalysts nanolayers on Ta3N5 photoanode surfaces could effectively promote the charge separation and hole transfer, while the subsequent formation of Ni catalysts nanolayers could provide the catalytic active-sites for water oxidation. Accordingly, their synergistic effects significantly improve the interfacial hole transfer and surface oxygen evolution kinetics, leading to an outstanding PEC water splitting activity. This work not only clarifies the intrinsic high-activity origins of NiFe/Ta3N5 photoanodes, but also provides new insights into the rational construction of highly efficient OER catalysts for PEC water splitting.

Enhanced photoactivity towards bismuth vanadate water splitting through tantalum doping: An experimental and density functional theory study

The activation of hole trap states in bismuth vanadate (BiVO4) is considered an effective strategy to enhance the photoelectrochemical (PEC) water-splitting activity. Herein, we propose a theoretical and experimental study of tantalum (Ta) doping to BiVO4 leading to the introduction of hole trap states for the enhanced PEC activity. The doping of Ta is found to alter the structural and chemical surroundings via displacement of vanadium (V) atoms that cause distortions in the lattice via the formation of hole trap states. A significant enhancement of photocurrent to ∼4.2 mA cm−2 was recorded attributing to the effective charge separation of efficiency of ∼96.7 %. Furthermore, the doping of Ta in the BiVO4 lattice offers improved charge transport in bulk and decreased charge transfer resistance at the electrolyte interface. The Ta-doped BiVO4 displays the effective production of hydrogen (H2) and oxygen (O2) under AM 1.5 G illumination with a faradaic efficiency of 90 %. Moreover, the density functional theory (DFT) study confirms the decrease in optical band gap and the activation of hole trap states below the conduction band (CB) with a contribution of Ta towards both valence and CB that increases the charge separation and majority charge carrier density, respectively. The findings of this work propose that the displacement of V sites with Ta atoms in BiVO4 photoanodes is an efficient approach for enhanced PEC activity.

2D Ti3C2 MXene interfaced ZnO/WO3 thin film nanostructures towards improved photoelectrochemical water splitting

We explored the morphology evolution approach for sustained photoelectrochemical (PEC) water splitting by developing dual heterojunction. Herein, novel ZnO/WO3/Ti3C2 photoelectrode has been developed for the first time by the integration of flake-like ZnO, nanocrystal featured WO3, and layer-structured two-dimensional (2D) Ti3C2 MXene morphologies towards PEC activity under simulated solar light. By adjusting the radio frequency (RF) magnetron sputtering and post-annealing, flake-like/nanocrystals featured ZnO/WO3 heterostructure observed with uniform growth of WO3 nanocrystals over the flake-like ZnO. Further, efficient integration of layer-structured 2D Ti3C2 MXene on ZnO/WO3 was provided through spin-coating. Utilizing robust surface interface between ZnO, WO3, and Ti3C2, optical transmittance and band gap have been modified. Accordingly, ZnO/WO3/Ti3C2 improved the photocurrent generation about 1.4 × 10−3 A/cm2 compared to pure ZnO (7.8 × 10−4 A/cm2) and ZnO/WO3 (1.1 × 10−3 A/cm2) at +0.4 V. These findings further provided a photoconversion efficiency of 1.16 % by the ZnO/WO3/Ti3C2 at +0.4 V. The PEC studies proved that electrically conductive Ti3C2 MXene can significantly separate the charge carriers from ZnO/WO3. On the other hand, this morphology-induced architecture proved sustainable surface interaction with KOH electrolyte than Na2SO3 and Na2SO4 media. Overall, the above developments suggest a robust interface in ZnO/WO3/Ti3C2 under controlled surface morphology and PEC water splitting activity.

Visible light active ZnIn2S4/g-C3N4 heterostructure nanocomposite photoelectrode for efficient photoelectrochemical water splitting activity

Hexagonal zinc indium sulfide coupled g-C3N4 (H-ZnIn2S4/g-C3N4) nanocomposites were synthesized using chemisorption method and its performance towards photoelectrochemical water splitting activity was studied. The H-ZnIn2S4/g-C3N4 (H-ZIS/CN) nanocomposites exhibited ∼ 1.9 times enhanced photoelectrochemical performance as compared to the H-ZnIn2S4. The enhancement in the PEC water splitting activity of H-ZIS/CN nanocomposite is ascribed to the formation of type-II heterojunction which resulted in improved separation of photogenerated charge carriers and faster transfer of charges at the photoelectrode/electrolyte interface. The electrochemical impedance study and Mott-Schottky supported these results. Moreover, during photoelectrochemical reactions, H-ZIS/CN nanocomposites showed tremendous stability under visible light. A potential mechanism of the enhanced photoelectrochemical activity of H-ZIS/CN nanocomposites was proposed and endorsed by the PEC results. This study demonstrates that establishing a heterostructure system by coupling a ternary chalcogenide semiconductor with a conducting polymer is an effective strategy for PEC water splitting applications.

Two-dimensional perovskite SrNbO2N with Zr doping for accelerating photoelectrochemical water splitting

• Two-dimensional SrNbO 2 N:Zr plates were nitrided from layered perovskite Sr 5 Nb 4 O 15 . • Zr 4+ was doped in Sr 5 Nb 4 O 15 during flux-assisted calcination. • The 2D SrNbO 2 N:Zr photoanode (λ<680 nm) exhibited high PEC activity. • The photoactivity mainly originated from the 2D surface morphology of SrNbO 2 N:Zr. • Controlling the surface morphology of SrNbO 2 N accelerates separation and transfer of charges. The superior ability of perovskite-type SrNbO 2 N to absorb intensive visible light makes it a potential semiconductor to produce hydrogen and oxygen by photoelectrochemical (PEC) water splitting under sunlight. The surface morphologies, such as shape and structure, of the oxynitride strongly affect its photoactivity, although the mechanism has been hardly studied. Herein, we report a two-dimensional (2D) porous SrNbO 2 N plate with Zr doping, nitrided from layered perovskite Sr 5 Nb 4 O 15 and also its largely enhanced PEC water splitting activity. Zr 4+ was doped in Sr 5 Nb 4 O 15 during flux-assisted calcination using KCl, producing 2D-type truncated-octahedral Sr 5 Nb 4 O 15 :Zr plates approximately 50 nm in thickness. The nitridation completely transformed Sr 5 Nb 4 O 15 :Zr to 2D single-crystalline SrNbO 2 N:Zr with a large surface area, which was subsequently used to fabricate a thin and uniform photoanode by the spin coating method. As a result, the Co(OH) x /SrNbO 2 N:Zr/FTO photoanode capable of absorbing visible light of up to 680 nm exhibited an activity of 2.0 mA cm −2 at 1.23 V vs the reversible hydrogen electrode for water splitting under AM 1.5G simulated sunlight. This improvement in photoactivity mainly originated from the 2D surface morphology of SrNbO 2 N:Zr, which is clearly distinguishable from 3D-type oxynitrides. According to electrochemical analyses, the 2D structure of SrNbO 2 N:Zr boosted the separation and accelerated the transfer of charges photogenerated during the water splitting, thus driving the reaction further. Therefore, the result empirically demonstrates that controlling the surface morphology of SrNbO 2 N is an effective strategy to suppress the recombination of charges and minimize their diffusion pathway, eventually enhancing the PEC activity.

Pyrite (FeS2)‐decorated 1D TiO2 nanotubes in a bilayer as a sustainable photoanode for photoelectrochemical water splitting activity

AbstractHerein, FeS2@TiO2 nanotubes photocatalyst was prepared by electrochemical anodization method followed by successive ionic layer adsorption and reaction method, and then finally annealed in a tube furnace for homogenous crystallization. The surface morphology, elemental composition, optical properties, and crystalline structure of the prepared FeS2@TiO2 nanocomposite were found out by performing scanning electron microscopy, energy dispersive X‐ray spectroscopy, X‐ray diffraction, UV–Vis diffuse reflectance spectroscopy, and fluorescence spectroscopy, respectively, while bonds vibrations and various functional groups' presence were analyzed using Raman and Fourier transform infrared spectroscopy. A higher photocurrent density of 1.59 mA/cm2 at 0.3 V versus reference electrode of Ag/AgCl (1.23 V versus reversible hydrogen electrode) using 100 mW/cm2 intensive light source was shown by 15‐FeS2@TiO2 nanotubes (uniformly loaded photoanode) while donor density (ND) of 3.68 × 10−13 cm−3 as compared to pure TiO2 NTs (0.09 mA/cm2), 05‐FeS2@TiO2 NTs (0.19 mA/cm2), 10‐FeS2@TiO2 NTs (0.53 mA/cm2) and 20‐FeS2@TiO2 NTs (0.61 mA/cm2), respectively. The exceptional photoelectrochemical activity results were attributed to the homogenous integration of FeS2 that not only increase the charge separation but also, intensively interacted with the substrate (TiO2 nanotubes), which results in an excellent photoelectrochemical activity.

A novel BiVO4/DLC heterojunction for efficient photoelectrochemical water splitting

Photoelectrochemical (PEC) water splitting is a promising technology to produce renewable hydrogen, which still faces problems of low photoelectric efficiency and instability. This work introduces a novel Type II heterojunction consisting of BiVO4 thin film and diamond-like carbon (DLC) to the PEC system as a photoanode and achieves an increased PEC water-splitting activity. Compared to the pure BiVO4, the BiVO4/DLC heterojunction has an increased photocurrent density from 0.79 mA cm−2 to 2.39 mA cm−2 at 1.23 V vs RHE, and the IPCE from 4.8 % to 23.4 %. After 120 min (180 cycles) of PEC water splitting, the BiVO4/DLC heterojunction retains up to 82.3 % of the initial photocurrent density value, while the pure BiVO4 has only 33.99 % remaining under the same conditions. Furthermore, the PEC system of BiVO4/DLC reaches the evolution rate of hydrogen of over 0.32 mmol h−1 cm−2, which is much higher than that of its counterparts. We ascribe the enhancement in PEC performance to the Type II heterojunction photoanodes that greatly promote carrier mobility and reduce the recombination rate of electron-hole pairs. We also identify that the band bending and depletion layer are the main reasons for the decrease in charge transfer and interface resistance. It is demonstrated that the sp2 carbon phase in DLC acts as a conductive channel to improve the separation and migration efficiency of free carriers, while the sp3 carbon phase provides stable support and passivation effect to the photoanode, thereby leading to an enhancement for both PEC water splitting performance and the long-time stability. This work provides an effective way to improve the BiVO4 photoanode-based PEC water-splitting systems.

Polymeric carbon nitride as a platform for photoelectrochemical water-splitting cells.

Polymeric carbon nitride (CN) materials are promising low-cost photocatalysts that exhibit a combination of chemical and physical properties suitable for converting light into redox activity on their surface. In this perspective, we describe our experience with this family of materials as light absorbers that serve as an anode in photoelectrochemical cells toward water-splitting. We describe some of the CN deposition techniques and procedures established in our lab. The knowledge gained from powder-based photocatalysis is implemented in photoelectrochemical scenarios and is used to determine the merits and shortcomings of resulting layers. We show how the preparation methods are oriented based on these factors and how high photoelectrochemical water-splitting activity develops in photoanodes we developed where CN(s) act as photoabsorbers. Lastly, we present our view on the future prospects of this field.

Lead‐Free Bismuth‐Based Halide Perovskites with Excellent Stability for Visible‐light‐Driven Photoelectrochemical Water Splitting

AbstractLead‐free halide perovskites have been developed as an alternative to lead‐based perovskite materials. Bi‐based halide perovskites Cs2AgBiCl6 and Cs3Bi2Cl9 are synthesized through the hydrothermal method and investigated their photoelectrochemical properties toward water splitting. The formation of the halide perovskites is confirmed by XRD, Raman spectroscopy, SEM, EDAX and XPS techniques. Optical properties are measured by UV‐Vis spectroscopy and Mott‐Schottky plots confirmed that both the materials are p‐type semiconductors with a bandgap of 2.72 eV and 3.05 eV for Cs2AgBiCl6 and Cs3Bi2Cl9 respectively. The photocurrent density of water oxidation on Cs2AgBiCl6 and Cs3Bi2Cl9 are 10 μA/cm2 and 6 μA/cm2 at 0.9 V (vs Ag/AgCl) respectively and both are highly stable over 300 sec under chopped condition and also the photoelectrocatalyst stable over 10 h during the chronoamperometry studies. The experimental data shows that the photoelectrochemical water splitting activity of Cs2AgBiCl6 is better than Cs3Bi2Cl9. This work suggests these materials will be a potential candidate for green hydrogen and oxygen production using solar energy.