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The development of robust and efficient photocatalytic constructs for boosting the water oxidation reaction (WOR) is needed for establishing a sunlight-driven renewable energy infrastructure. Here, we synthesized plasmonic core–shell nanoconstructs consisting of triangular gold nanoprism (AuTNP) core with mixed manganese oxide (MnOx) shell for photoelectrocatalytic WOR. These constructs show electrocatalytic WOR with a low onset overpotential requirement of 270 mV at pH 10. Photoexcitation showed further enhancement of their catalytic activity resulting in ∼15% decrease of the onset overpotential requirement along with the generation of photocurrent density of up to 300 μA/cm2. We showed that such light-driven enhancement of AuTNP@MnOx dyad's catalytic activity toward the WOR process includes contributions from both photocatalytic (hot carriers driven) and photothermal effects with photothermal effect playing the major role for wavelength between 532 and 808 nm. The contribution from the photocatalytic effect is appreciable only for high-energy excitations near the interband region, while the photothermal effect largely dominates for lower energy excitations near the LSPR wavelengths of the dyad. [ABSTRACT FROM AUTHOR]

A copper(I) donor–chromophore–acceptor triad bearing 1,8-napthalenemonoimide as the electron acceptor and triphenylamine as the electron donor was synthesized. Photophysical and electrochemical characterization suggest stepwise photoinduced charge separation upon excitation of the copper(I)-based metal-to-ligand charge transfer (MLCT) transition. Analyses of femtosecond transient absorption data of the triad show that intersystem crossing from the 1MLCT to the 3MLCT state is followed by two electron-transfer steps with time constants of 20 ps and 722 ps yielding a presumed final charge-separated state with a radical cation on the donor and radical anion on the acceptor that has an 18 ns lifetime in acetonitrile. Finally, this triad was anchored onto n-type (ZnO) and p-type (NiO) semiconductor surfaces to construct a photoanode and photocathode respectively. Successful photocurrent generation from both electrodes upon white light illumination confirms the potential utilization of such systems in dye-sensitized photoelectrochemical cells. [ABSTRACT FROM AUTHOR]

Z-scheme photocatalysts for solar-driven overall water splitting have attracted tremendous attention due to their strong redox abilities and enhanced solar-light absorptions. This study focuses on the theoretical design of XAu 2 Y (X, Y S, Se, Te) heterostructures for solar-driven photocatalytic water splitting based on first-principles calculations. The band edges and internal electric fields indicate that SAu 2 S/TeAu 2 Te, SeAu 2 Se/TeAu 2 Te, TeAu 2 Te/SAu 2 Se and TeAu 2 Te/SeAu 2 S are highly efficient Z-scheme photocatalysts for solar-driven overall water splitting, with enhanced optical absorbances by 1.5–2 times and high solar-to-hydrogen energy conversion efficiencies of 20.47%, 19.94%, 16.50% and 22.81%. Furthermore, taking TeAu 2 Te/SeAu 2 S as an example, HER (Δ G H * = 0.16 e V) and OER (U = 2.25 V) reactions show excellent photocatalytic performances. These results extend the scope of solar-driven overall-water-splitting photocatalysts to group-11 chalcogenides heterostructures, which is expected to inspire the experimental fabrications and relative investigations. Z-scheme heterostructures based on XAu 2 Y (X, Y S, Se, Te) are theoretically screened for solar-driven overall water splitting, which exhibit enhanced optical absorbances, high solar-to-hydrogen energy conversion efficiencies and excellent redox reactions. [Display omitted] • The Z-scheme heterostructures are designed to effectively separate photogenerated carriers. • Constructing heterostructures promote the excellent optical absorbances. • The Z-scheme heterostructures possess high solar-to-hydrogen energy conversion efficiencies. • High catalytic activities for HER and OER are confirmed by the Gibbs free energies. [ABSTRACT FROM AUTHOR]

The development of tandem photovoltaics and photoelectrochemical solar cells requires new absorber materials with bandgaps in the range of ≈1.5–2.3 eV, for use in the top cell paired with a narrower‐gap bottom cell. An outstanding challenge is finding materials with suitable optoelectronic and defect properties, good operational stability, and synthesis conditions that preserve underlying device layers. This study demonstrates the Zintl phosphide compound CaZn2P2 as a compelling candidate semiconductor for these applications. Phase‐pure, ≈500 nm‐thick CaZn2P2 thin films are prepared using a scalable reactive sputter deposition process at growth temperatures as low as 100 °C, which is desirable for device integration. Ultraviolet‐visible spectroscopy shows that CaZn2P2 films exhibit an optical absorptivity of ≈104 cm−1 at ≈1.95 eV direct bandgap. Room‐temperature photoluminescence (PL) measurements show near‐band‐edge optical emission, and time‐resolved microwave conductivity (TRMC) measurements indicate a photoexcited carrier lifetime of ≈30 ns. CaZn2P2 is highly stable in both ambient conditions and moisture, as evidenced by PL and TRMC measurements. Experimental data are supported by first‐principles calculations, which indicate the absence of low‐formation‐energy, deep intrinsic defects. Overall, this study shall motivate future work integrating this potential top cell absorber material into tandem solar cells. [ABSTRACT FROM AUTHOR]

In this study, textile‐based microbial photoelectrochemical solar cells are developed for flexible electronic device applications. Configuration of the self‐pumping microfluidic channel without a proton exchange membrane is adopted to miniaturize the biophotovoltaic device. The microchannel region of the miniature device is patterned by silk screen printing using a body‐friendly Ecoflex to maintain the flexibility of the fabric substrate. Gold nanoparticle biosynthesized Synechocystis sp. PCC 6803 biocatalyst, supercapacitive ternary nanocomposite anode, and solid‐state Ag2O oxidant are used to enhance the biosolar cell performance. A maximum current density of 135.1 µA cm−2 and peak power density of 14.1 µW cm−2, which are higher than previous textile‐based microbial fuel cells, are achieved in the presence of light. The monolayer fabric‐based biosolar cell has a stable performance up to 100 and 20 cycles of stretching and twisting, respectively. The presented new platform of flexible microbial solar cells offers the development possibility of self‐sustaining wearable electronics. [ABSTRACT FROM AUTHOR]

Considering agricultural wastes as carbon source to be utilized for the preparation of porous carbon (PC), in particular with the advantages of low cost and abundant active sites, we construct a one-compartment membraneless photoelectrochemical cell use cornstalk-based PC as cathode instead of commercial carbon paper. The addition of as-prepared PC with high surface area at cathode is beneficial to provide a large number of reaction sites for H 2 O 2 storing compared with commercial carbon paper. The maximum power density of this H 2 O 2 fuel cell with PC/ITO-based cathode achieves 1.68 mW cm−2 under AM 1.5G solar light (1 sun, 100 mW cm−2) in 0.1 M HCl electrolyte at air atmosphere, which presents around 21.3- and 3.3-times enhancement compared to the cell with bare ITO-based cathode (0.079 mW cm−2) and the cell with carbon paper-based cathode (0.51 mW cm−2), respectively. Consequently, the calculated solar-to-electricity conversion efficiency (SECE) is as high as 1.04%. Furthermore, the cell can produce H 2 O 2 from g-C 3 N 4 on the photoanode side through photocatalytic H 2 O oxidation, and adsorptively store H 2 O 2 on the cathode side by using of hierarchical nanostructures of PC with the disconnection of electrodes. After 0.5 h of light irradiation, the cell using H 2 O 2 as the fuel operated by connecting the electrodes in the dark can form a specific capacitance of 19451.3 mF cm−2. We propose a pathway to utilize biomass-based PC as the cathode instead of commercial carbon paper in a one-compartment H 2 O 2 fuel cell for the first time, which is unquestionably more promising for high-value use of agricultural wastes and the development of high-performance and low-cost fuel cells. Cornstalk-derived porous carbon with high specific surface area that can be modified to ITO as the cathode has been successfully applied to photoelectrochemical H 2 O 2 fuel cell. [Display omitted] • Cornstalk-derived porous carbon (PC) as the cathode instead of commercial carbon paper in a one-compartment H 2 O 2 fuel cell. • The hierarchical nanostructures of PC facilitate H 2 O 2 storage on the cathode side. • The cell with PC/ITO-based cathode converts solar energy to H 2 O 2 fuel for generating electricity. • The specific capacitance keeps 45.5% of initial value after 12 h of cell operation. [ABSTRACT FROM AUTHOR]

Photoelectrochemical cells (PEC) use solar energy to generate green hydrogen by water splitting and have an integrated device structure. Achieving high solar‐to‐hydrogen conversion (STH) efficiency along with a long operational lifetime in these cells is crucial for the production of low‐cost green hydrogen as a viable energy source. Several functional components, such as photo absorber, charge transport, and catalyst layers are interfaced in these cells to form a compact monolithic device. In this review, therefore, the engineering and design of the individual components of these cells, the interplay between them, and their interfaces are discussed in detail, as these factors determine the overall performance of the cells. The main emphasis is on halide perovskite (HP) photo absorbers, which have emerged as promising materials for use in these cells due to their superior optoelectronic properties. Recent advances in the development of efficient and stable perovskite‐based cells are highlighted and reviewed. The design of catalysts for water splitting and the effect of factors such as pH and supporting cations are also examined. Finally, the scientific challenges and future directions for designing perovskite‐based photoelectrochemical cells are discussed. This review can help researchers further advance this technology toward commercial production of green hydrogen. [ABSTRACT FROM AUTHOR]

Photoelectrochemical setups based on semiconductor photoelectrodes are known for their effectiveness in wastewater treatment, powered by solar energy, which is a renewable and sustainable source. These systems require semiconductor photocatalysts with excellent light-absorbing properties and high stability in aqueous environments. In this regard, silicon is highly investigated in solar cells thanks to its narrow bandgap, making it a potential solar harvester. Metal oxides stand as promising semiconductors, which are non-toxic and thermodynamically stable. In this work, two high-efficiency silicon-based cells have been investigated via Solar Cell Capacitance Simulator (SCAPS-1D) software. Thickness and doping concentration, of each layer, have been scrutinized for multiple buffer propositions to investigate the physical feasibility and optimal values allowing maximal light harvesting. It was found that the overall cell performance is influenced by extremely high doping concentrations for some layers. The effect of temperature was investigated as well at temperatures ranging from 300 to 350 K; it was discovered that the cell demonstrates great performance at the ambient temperature. A maximum solar efficiency of about 25.44% was calculated. Our findings build the path towards fabricating highly efficient Si-based solar cells for photoelectrochemical wastewater treatment. [ABSTRACT FROM AUTHOR]

Developing transparent and efficient photoanodes is a challenging but essential task in tandem photoelectrochemical cell for unassisted solar water splitting without an external bias. Here we report construction of p–n homojunction hematite photoanodes by hybrid microwave annealing-induced single antimony doping, which results in the gradually-increased valence states from the surface to the inside by the unique features of hybrid microwave annealing. The Sb-doped p–n homojunction hematite photoanode exhibits improved performance and displays a good transparency, achieving a stable photocurrent density of ~4.21 mA cm−2 at 1.23 VRHE under 100 mW cm−2 solar irradiation, which is comparable to the reported state-of-the-art hematite photoanodes. More importantly, a parallel-connected stack of six photoanodes of transparent p–n homojunction records a near-theoretical photocurrent density of ~10 mA cm–2 at 1.23 VRHE under standard photoelectrochemical water splitting conditions, which serves as a useful reference for hematite photoanodes and promises its practical application for unbiased photoelectrochemical water splitting. Developing efficient and transparent photoanodes for solar water splitting is crucial for advancing clean energy technologies. Here, the authors report Sb-doped p–n homojunction hematite photoanodes that achieve high transparency and a stable photocurrent density of 4.21 mA cm–2. [ABSTRACT FROM AUTHOR]

We introduce a theoretical model for the photocurrent-voltage (I-V) characteristics designed to elucidate the interfacial phenomena in photoelectrochemical cells (PECs). This model investigates the sources of voltage losses and the distribution of photocurrent across the semiconductor–electrolyte interface (SEI). It calculates the whole exchange current parameter to derive cell polarization data at the SEI and visualizes the potential drop across n-type cells. The I-V model's simulation outcomes are utilized to distinguish between the impacts of bulk recombination and space charge region (SCR) recombination within semiconductor cells. Furthermore, we develop an advanced deep neural network model to analyze the electron–hole transfer dynamics using the I-V characteristic curve. The model's robustness is evaluated and validated with real-time experimental data, demonstrating a high degree of concordance with observed results. [ABSTRACT FROM AUTHOR]

Limited charge transfer and slow oxygen evolution (OER) kinetics significantly impede the practical realization of photoanodes for photoelectrochemical (PEC) water splitting. Here, pn-type-Fe 2 O 3 homojunction photoanode catalysts with P active sites are designed by doping phosphorus (P) into outer lattice of n-type Fe 2 O 3 nanorods (pn-P-Fe 2 O 3). The optimized pn-P-Fe 2 O 3 photoanode shows the maximum photocurrent density of 2.61 mA/cm2 at 1.23 V RHE , and the value is 6.4 times greater than that of pristine Fe 2 O 3. Experimental and theoretical results clearly show that the P–N homogeneous junctions constructed in Fe 2 O 3 through P-doping increase active sites for H 2 O adsorption and activation, reduce OER reaction energy barrier, and promote effective separation of photogenerated electron-hole pairs and water splitting kinetics. This not only makes the photoelectric water decomposition performance outstanding, but also produces excellent durability. This work provides a novel simple and environmentally friendly strategy for designing effective photoanodes for PEC water splitting. • The homojunction photoanode catalyst with P active sites is designed by P doping. • The photocurrent density of pn-P-Fe 2 O 3 is 6.4 times higher than pristine Fe 2 O 3. • P active sites and the P–N homojunction reduce the energy barrier of OER. [ABSTRACT FROM AUTHOR]

Anchoring groups play an important role in the assembly of functional molecules onto semiconductor substrates for dye‐sensitized photocatalysis. In addition to directly influencing the adsorption stability, anchoring groups significantly impact the efficiency of electron or hole injection into the substrate, which is a crucial step for photocatalytic reactions. Most reported dye‐sensitized photocatalytic systems, including semiconductor nanoparticles and photoelectrochemical cells, are prepared using the carboxylic or phosphonic acid anchors. The systems prepared with these conventional anchors usually suffer from low adsorption stability in aqueous media. Alternatively, pyridine has emerged as an anchoring group of photosensitizers and molecular catalysts in the construction of photocatalytic systems. The resulting semiconductor nanoparticles and photoelectrodes show superior adsorption stability in aqueous media, providing a simple and efficient way to sensitize the metal or metal oxide substrate. This review focuses on the recent advances of such a pyridine anchoring strategy in the assembly of photosensitizers and molecular catalysts for photocatalytic applications, mainly including photocatalytic water oxidation, reduction, and splitting. The further exploration and understanding of the pyridine‐anchoring method are believed to boost the development of advanced dye‐sensitized photocatalytic devices and technologies. [ABSTRACT FROM AUTHOR]

Photocatalytic water splitting represents a leading approach to harness the abundant solar energy, producing hydrogen as a clean and sustainable energy carrier. Zinc indium sulfide (ZIS) emerges as one of the most captivating candidates attributed to its unique physicochemical and photophysical properties, attracting much interest and holding significant promise in this domain. To develop a highly efficient ZIS-based photocatalytic system for green energy production, it is paramount to comprehensively understand the strengths and limitations of ZIS, particularly within the framework of solar-driven water splitting. This review elucidates the three sequential steps that govern the overall efficiency of ZIS with a sharp focus on the mechanisms and inherent drawbacks associated with each phase, including commonly overlooked aspects such as the jeopardising photocorrosion issue, the neglected oxidative counter surface reaction kinetics in overall water splitting, the sluggish photocarrier dynamics and the undesired side redox reactions. Multifarious material design strategies are discussed to specifically mitigate the formidable limitations and bottleneck issues. This review concludes with the current state of ZIS-based photocatalytic water splitting systems, followed by personal perspectives aimed at elevating the field to practical consideration for future endeavours towards sustainable hydrogen production through solar-driven water splitting. [ABSTRACT FROM AUTHOR]

To design a high‐efficiency crystalline silicon (c‐Si) photocathode, the photovoltage and photocurrent generated by the device must be maximized because these factors directly affect the hydrogen evolution reaction (HER). In this study, a c‐Si p–n junction is used to enhance the photovoltage of the c‐Si photocathode, and a tapered microwire array structure is introduced to increase the photocurrent. When tapered microwire arrays are employed on the front surface of the c‐Si photocathode, a current density of ≈41.7 mA cm−2 is achieved at 0 VRHE (reversible hydrogen electrode); this current density is the highest among all reported photocathodes including c‐Si, approaching the theoretical maximum value for c‐Si. Furthermore, a Ni foil/Pt catalyst is introduced on the opposite side of the incident light, simultaneously serving as an electrocatalyst to reduce side reactions in the HER and encapsulation layer to prevent c‐Si from contacting the electrolyte. Thus, a stable device is developed using c‐Si photoelectrochemical cells that have an efficiency exceeding 97% for >1000 h. [ABSTRACT FROM AUTHOR]

Photoelectrochemical (PEC) cells offer a promising method for producing green hydrogen through the splitting of water using solar energy. However, the cost‐effective synthesis of highly crystalline p‐type semiconductor materials for PEC cells remains a significant challenge for industrial applications. Herein, a CuInS2 photoelectrode is fabricated using a scalable and economical wet chemical spin‐coating technique. To enhance the crystallinity and photoelectrochemical activity of the photoelectrode, the grain size is precisely controlled by adjusting the atomic ratio, thickness, morphology, and Ag doping. Evaluating a novel growth mechanism of CuInS2 from Cu–In–O reveals that Ag doping significantly promotes grain growth. Consequently, the CuInS2 photocathode achieves one of the highest photoelectrochemical activities (−9.8 mA cm−2 at 0 VRHE) reported for CuInS2 photoelectrodes synthesized via wet chemical methods. Bias‐free water splitting is achieved using a CuInS2‐based photoelectrode in a photovoltaic–PEC cell configuration. These results highlight the potential of CuInS2, prepared through wet chemical methods, for cost‐effective photoelectrochemical water splitting. [ABSTRACT FROM AUTHOR]

Polymeric carbon nitride (CN) has emerged as a promising photoanodic material in water‐splitting photoelectrochemical cells (PEC). However, the current deposition methods of CN layers on substrates usually include a long heating process at 500−550 °C, which might cause sublimation or decomposition of the CN monomers and destruction of the substrate, leading to a nonuniform CN film. Herein, a simple, fast, and scalable energy‐economic procedure to synthesize homogenous CN films is introduced. The predesigned CN monomers film is subjected for several minutes to higher temperatures than the standard calcination procedure. The short heating process allows the formation of a uniform CN layer, with excellent contact with the substrate and good activity as a photoanode in PEC. The optimal CN photoanode reaches photocurrent densities of ≈200 μA cm−2 at 1.23 versus reversible hydrogen electrode in neutral and acidic solutions and 120 μA cm−2 in a basic solution. [ABSTRACT FROM AUTHOR]

In this investigation, copper selenide (Cu2−xSe, x = 0.57) thin films were synthesized employing the environmentally benign self-organized arrested precipitation technique (APT) on the soda-lime glass (SLG) as well as on tin-doped indium oxide (ITO) substrates, varying deposition temperatures of 40 °C, 55 °C, 70 °C. Characterization, encompassing UV–Vis spectrophotometry, X-ray diffraction (XRD), and scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS). The results elucidated distinctive attributes of the thin films, having a notably visible light absorption profile in the range of 600–700 nm for all samples and characterized by bandgap energy of 1.59 eV for the sample at 70 °C. The manifestation of a singularly phase-pure cubic crystal structure for temperature of 70 °C and hexagonal for 45 °C and 55 °C temperatures, and the emergence of nanospherical surface morphology. Significantly, the Cu2−xSe thin films evinced augmented photoelectrochemical (PEC) proficiency, prolonged stability in PEC environments, and exhibited consistent p-type conductivity. Underscoring their prospective utility in energy conversion, particularly in the context of photoelectrochemical cells. [ABSTRACT FROM AUTHOR]

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[Display omitted] • Bio-inspired NF@PTA/2PACz/BVO photosystem were designed. • 2PACz HTLs passivate the surface traps. • 2PACz HTLs can accelerate the charge transfer. • The C O Fe bond can stabilize the metal site. • Uncoordinated (COOH) carboxylate groups accelerate proton transfer. Charge transport and metal site stability play a critical role on realizing efficient solar water splitting in photoelectrochemical devices. Here, we investigated BiVO 4 -based composite photoanodes (labelled as NF@PTA/2PACz/BVO) in which BiVO 4 , [2-(9H-carbazol-9-yl) ethyl] phosphonic acid (2PACz) hole transport layers based on self-assembled monolayers (SAMs), and terephthalic acid (PTA)-functionalized NiFeOOH (NF@PTA) oxygen evolution cocatalysts (OECs) structurally similar to the OECs in natural photosystem II, were assembled sequentially. Alignment of energy levels and stabilization of metal sites can be achieved by this layer-designed structure. And the uncoordinated (COOH) carboxylate groups can accelerate the proton transfer. Fundamental investigations reveal that the NF@PTA/2PACz/BVO photoanode exhibits unique properties including passivated surface traps, excellent carrier density and lifetime, enlarged photovoltage, and smoother hole transport band structure. Consequently, the optimum NF@PTA/2PACz/BVO photoanode shows the photoelectrochemical (PEC) performance of 5.43 mA cm−2 at 1.23 V vs reversible hydrogen electrode with an applied bias photon-to-current efficiency of 1.45 %. The coupled C O Fe bond between the coordinating carboxylate and the metals not only inhibits the leaching of the metal species but also maintains a steady photocurrent density over 20 h of stability test. Our work paves the way for the development of more efficient PEC cells with superior charge separation and breakthroughs in the stability of metal active sites, thus broadening their potential applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • The PEC performance are closely related to the photoanode's thickness and concave structure. • The simulation results demonstrate that the concave structure presents a significant improvement effect for PEC. • The PEC performance enhanced mechanism by the concave structure are revealing. Solar energy converted by photoelectrochemical (PEC) cells showcases significant potential for addressing the energy crisis. However, limitations stemming from photoelectrode structure have hindered the efficiency improvements of PEC cells. In this work, we utilized the finite-time domain difference method to simulate the PEC performance of GaAs photoanode in a PEC cell. Through finite element analysis, we determined the thickness of GaAs photoanode to be 265 nm and subsequently designed the concave-structured photoanode. Comparison of cross-sectional photoelectric characteristic between flat and concave structured photoanodes revealed significant improvements in the latter. Specifically, the absorption of concave structure increased by 30.61 % compared to flat structure, accompanied by 2.7 times increase in P max and 2.2 times increase in J SC. Further analysis of the impact of depth-to-width ratio and inner surface area on light-trapping characteristics demonstrated their influence on absorption and photoelectrical performance. Interestingly, concave structures presented a 14.70 % higher absorption compared to flat structures, translating to 1.48 times increase in surface area absorption rate. Moreover, the P max increase was 3.08 times greater than the increase in surface area. We anticipate that our structural simulation findings will offer valuable theoretical insights for the design of light-trapping structures, thereby enhancing the performance of PEC cells. [ABSTRACT FROM AUTHOR]

[Display omitted] The recombination of photogenerated electron-hole pairs of the photoanode seriously impairs the application of bismuth vanadate (BiVO 4) in photoelectrochemical water splitting. To address this issue, we prepared a Yb:BiVO 4 /Co 3 O 4 /FeOOH composite photoanode by employing drop-casting and soaking methods to attach Co 3 O 4 /FeOOH cocatalysts to the surface of ytterbium-doped BiVO 4. The prepared Yb:BiVO 4 /Co 3 O 4 /FeOOH photoanode demonstrates a high photocurrent density of 4.89 mA cm−2 at 1.23 V versus the reversible hydrogen electrode (RHE), which is 5.1 times that of bare BiVO 4 (0.95 mA cm−2). Detailed characterization and testing demonstrated that Yb doping narrows the band gap and significantly enhances the carrier density. Furthermore, Co 3 O 4 serves as a hole transfer layer to expedite hole migration and diminish recombination, while FeOOH offers additional active sites and minimizes surface trap states, thus boosting stability. The synergistic effects of Yb doping and Co 3 O 4 /FeOOH cocatalyst significantly improved the reaction kinetics and overall performance of PEC water oxidation. This work provides a strategy for designing efficient photoanodes for PEC water oxidation. [ABSTRACT FROM AUTHOR]

Bismuth vanadate (BVO) ranks among the most promising photoanodes for photoelectrochemical (PEC) water splitting. Nonetheless, slow charge separation and transport, besides the sluggish water oxidation kinetics, are key barriers to its photoefficiency. Here, we present a co‐doping strategy that significantly improves the charge separation performance of BVO photoanodes. We found that, under standard one sun illumination, the Fe−N co‐doped BVO photoanode (Fe−N−BVO) by N‐coordinated Fe precursor reaches a record photocurrent density of 7.01 mA cm−2 at 1.23 V vs RHE after modified a surface co‐catalyst (FeNiOOH), and exhibits an outstanding stability. By contrast, much lower photocurrent density is obtained for the N‐doped, Fe‐doped and Fe/N‐doped BVO photoanode with separated N and Fe precursors. The detailed experimental characterizations show that the high activity of the Fe−N co‐doped BVO photoanode is attributed to the enhanced photo‐induced bulk charge separation, as well as the accelerated surface water oxidation kinetics. XPS, EXAFS and DFT calculations clearly show that, instead of formation of deep trapping state in the individually doped BVO, the co‐doping of Fe−N into BVO generates Fe‐based electronic states just below the bottom of conduction band and N‐derived states just above the top of valence band. Such modulations in electronic structure enable the efficient trap of the electrons and holes to enhance the separation of photo‐induced carriers, but hinder the charge recombination originated from the deep trapping sites. [ABSTRACT FROM AUTHOR]

The development of photoelectrochemical tandem cells for water splitting with electrodes entirely based on metal oxides is hindered by the scarcity of stable p-type oxides and the poor stability of oxides in strongly alkaline and, particularly, strongly acidic electrolytes. As a novelty in the context of transition metal oxide photoelectrochemistry, a bias-free tandem cell driven by simulated sunlight and based on a CuCrO2 photocathode and a WO3 photoanode, both unprotected and free of co-catalysts, is demonstrated to split water while working with strongly acidic electrolytes. Importantly, the Faradaic efficiency for H2 evolution for the CuCrO2 electrode is found to be about 90%, among the highest for oxide photoelectrodes in the absence of co-catalysts. The tandem cell shows no apparent degradation in short-to-medium-term experiments. The prospects of using a practical cell based on this configuration are discussed, with an emphasis on the importance of modifying the materials for enhancing light absorption. [ABSTRACT FROM AUTHOR]

This paper describes photoelectrochemical dehydrogenative cyclization of 2-arylbenzoic acid and 2-arylbenzamide in a PEC cell consisting of a mesoporous WO3 photoanode and Pt cathode. The cyclization reaction is effectively driven by this PEC system at room temperature with blue LED irradiation under external oxidant- and metal-free conditions, delivering a series of benzolactones and benzolactams in up to 95% isolated yields. Meanwhile, hydrogen is released as the only byproduct of this process. [ABSTRACT FROM AUTHOR]

BiVO4 has garnered substantial interest as a promising photoanode material for photoelectrochemical water‐splitting due to its narrow band gap and appropriate band edge positions for water oxidation. Nevertheless, its practical use has been impeded by poor charge transport and sluggish water oxidation kinetics. Here, a hybrid composite photoanode is fabricated by uniformly embedding SnS2 nanoparticles near the surface of a BiVO4 thin film, creating a type II heterostructure with strong interactions between the nanoparticles and the film for efficient charge separation. This structure forms via eutectic melting during atomic layer deposition of SnS2 with subsequent phase separation between SnS2 and BiVO4 at room temperature, offering greater advantages and flexibilities over conventional exsolution techniques. Furthermore, the SnS2/BiVO4 hybrid composite is coated with a thin amorphous ZnS passivation layer to accelerate charge transfer process and enhance long‐term stability. The optimized BiVO4/SnS2/ZnS photoanode exhibits a photocurrent density of 5.44 mA cm−2 at 1.23 V versus RHE, which is 2.73 times higher than that of the BiVO4 photoanode, and a dramatic improvement in photostability retention at 1.23 V versus RHE, increasing from 55% to 91% over 24 hours. This method of anchoring nanoparticles onto host materials proves highly valuable for energy and environmental applications. [ABSTRACT FROM AUTHOR]

Narrow band gap oxide materials that harvest visible light have gained considerable attention for numerous visible light mediated applications. In this current work, a typical Mg doped CuO bulk material was prepared by a simple wet chemical method. The prepared material was annealed in three different temperatures viz.; 300 °C, 400 and 500 °C in air atmosphere to tune the optical band gap. XRD studies reveal that the average crystallite size increases with increase in annealing temperature. FESEM images of all the samples show their bulk nature with different grain sizes and morphologies. XPS survey scan spectra exhibit photoelectron emissions of Cu2p, O1s and Mg 1s with binding energies 933.69 eV, 533.41 eV and 1304.2 eV for all the samples and validated the effective incorporation of Mg ions into the CuO lattice. PL spectra reveal the polychromatic UV- visible luminescence bands for all the annealed samples, whereby the PL intensity is found to be decreasing as the annealing temperature increases. Finally, the band gap decreases with annealing temperature and indicates that the sample annealed at 500 °C can be exploited for visible light assisted applications such as solar cells, photocatalysis and photoelectrochemical cell. [ABSTRACT FROM AUTHOR]

Ferrites and ferrite-based composites are known for their fascinating magnetic properties, varied redox chemistry, good stability, and excellent catalytic properties, all of which make them useful for a growing range of energy-related applications. The present review provides a concise summary of the basic properties of ferrites, an overview of the applicable synthetic methods, and recent advances related to the application of ferrites and ferrite-based composites in photoelectrochemical cells, photocatalytic CO2 reduction, batteries, supercapacitors, and microbial fuel cells. Special emphasis is placed on materials prepared by modern techniques, including microwave-assisted synthesis, ultrasound-assisted and sonochemical methods, synthesis employing metal-organic framework precursors, and electrospinning methods. The effects of intrinsic magnetism and external magnetic fields on the efficiency of ferrites in selected energy applications are also highlighted. The review concludes with a future outlook for the field that proffers solutions to issues currently hindering the effective utilization of ferrites and ferrite-based composites in energy conversion and storage applications. Highlights: Overview of the preparation and electrochemical energy applications of ferrites and ferrite-based composites Recent applications of ferrites in photoelectrochemical cells, photocatalytic CO2 reduction, batteries, supercapacitors, and microbial fuel cells Effect of magnetism and external magnetic fields on the synthesis and electrochemical applications of ferrites [ABSTRACT FROM AUTHOR]

This study investigates the relationships among redox couple activity, electrolyte concentration, and efficiency in CdSe thin-film photoelectrochemical solar cells. A CdSe photo-electrode was prepared using the electro-depositing technique to produce well-staged layering of CdSe, followed by chemical bath deposition to produce a layer with an acceptable thickness to absorb enough photons to create a suitable amount of photocurrent. The CdSe photo-electrochemical cell was tested under various concentrations of a NaOH/Na2S/S electrolyte solution. The results showed that the activity of the redox couple greatly affected the efficiencies of the solar cells. Correlation plots between ionic strength and PEC efficiency with the Debye–Hückel equation yielded an R² value of 0.96, while those between ionic strength and photocurrent density had an R² value of 0.92. The correlation between concentration and PEC efficiency was much weaker. This paper highlights how optimal ionic activity increases the performance of photoelectrochemical solar cells, which consequently improves the conversion efficiency of solar energy. [ABSTRACT FROM AUTHOR]

Solar redox flow batteries (SRFB) have attracted increasing interest for simultaneous capture and storage of solar energy by integrating a photoelectrochemical cell with a redox flow battery. Herein, a scalable, nanostructured α‐Fe2O3 photoanode exhibiting a high photovoltage of 0.68 V in a fully integrated Na4Fe(CN)6/AQDS SRFB is demonstrated. Thanks to its optimal band alignment, it uniquely enables stable, unassisted photocharging of the SRFB up to a state‐of‐charge (SOC) higher than 50%. Concurrently, its improved charge transfer results in a record unbiased photocurrent density of 0.22 mA cm−2, with a sixfold increase at zero SOC compared to α‐Fe2O3 film. Through an in‐depth optical and photoelectrochemical characterization of different α‐Fe2O3 morphologies, the impact of nanostructuring on charge transfer is quantified. Most interestingly, an increase in unbiased photocurrent is observed at 10% SOC (0.31 mA cm−2) and attributed to adsorption of ferricyanide, which enhances charge transfer. Importantly, it is demonstrated that the superior performance is retained after device scale‐up to 5.72 cm2. Overall, the demonstrated unassisted device is on par with previously reported dye‐sensitized solar cell‐assisted hematite‐based SRFBs. More broadly, this work contributes to the real‐world deployment of cost‐effective SRFBs based on Earth‐abundant materials. [ABSTRACT FROM AUTHOR]

A biopolymer derived from Jatropha oil-based poly(ethyl carbamate) (PUA) has been used as gel polymer electrolyte (GPE) in optoelectronic devices and photoelectrochemical cells (PEC) as photodiode devices. The quasi-solid-state photodiode device was characterized through photo current–voltage analysis, photogenerated charge carrier dynamic analysis, electrochemical impedance spectroscopy (EIS) analysis, and voltammetry analysis. Sample A2 biopolymer electrolyte (95 wt.% PUA, 5 wt.% LiI, 5 wt.% I2) revealed the highest ionic conductivity (2.34 ± 0.01) × 10−4 S cm−1 and power conversion efficiency (5.09 ± 0.23) %, along with the highest short-circuit current density (17.80 ± 0.41) mA cm−2, open-circuit voltage (0.52 ± 0.01) V, and fill factor (0.55 ± 0.04). respectively. Moreover, sample A2 biopolymer electrolyte featuring a triiodide ion diffusivity of 1.82 × 10−8 cm2 s−1 demonstrated electrochemical stability up to 2.1 V and remained functional for a duration of 2000 cycles. The charge dynamic mechanism in the PEC proved that sample A2 biopolymer electrolyte recorded lowest values of Rs, Rpt, Rct, and Rd of (18.60 ± 0.01) Ω, (1.20 ± 0.01) Ω, (10.0 ± 0.01) Ω, and (11.50 ± 0.01) Ω, respectively. [ABSTRACT FROM AUTHOR]

A p–n heterojunction film consisting of p-type CuFe2O4 and n-type ZnFe2O4 was fabricated in this study. The n-type ZnFe2O4 film was deposited on a stainless steel substrate using the spray pyrolysis method, after which a top layer of p-type CuFe2O4 thin film was deposited and annealed. Characterization techniques, such as X-ray diffraction, scanning electron microscopy, UV–Vis diffuse reflectance spectroscopy, and photoluminescence, confirmed the formation of a superlattice p–n heterojunction between CuFe2O4 and ZnFe2O4. Photoelectrochemical measurements were conducted to investigate the photoelectrochemical properties of the samples, resulting in a photocurrent of 1.2 mA/cm2 at 1.5 V (vs. Ag/AgCl) under illumination from a 100-watt LED light source. Utilizing the p–n junction of CuFe2O4/ZnFe2O4 as a photoanode increased the hydrogen production rate by 30% compared to that of the dark measurement. This enhancement in performance was attributed to the potential barrier at the p–n heterojunction interface, which improved the separation of photoinduced electron–hole pairs and facilitated a more efficient charge transfer. Additionally, coating the stainless steel electrode with this ferrite sample improved both the corrosion resistance and the stability of hydrogen production over extended operation times. [ABSTRACT FROM AUTHOR]

In this paper, we report on a photocatalytic water-splitting device comprising a TiO2 photoanode combined with Se/TiO2heterojunction photovoltaic (PV) devices. A Se/TiO2PV device can supply its photo-induced open circuit voltage to a TiO2-Pt photoelectrochemical cell (PEC) in order to assist photoelectrolysis for H2 and O2 gas generation without external electrical sources. The open circuit voltage was increased from 0.65 V to approximately 3.2 V by the serial connection of five Se/TiO2PV devices. Hydrogen and oxygen bubbles were successfully generated by only light illumination without using any wired external voltage source. A photoanode with sol–gel derived porous TiO2films was used to increase the surface area to attain a stronger photocatalytic reaction. Microdot patterns of Pt were formed as the co-catalyst on a TiO2photoanode to suppress the back reaction of the photogenerated carrier. A Pt anode was formed on a glass substrate. Parameters related to the photocatalytic reaction, such as atmospheric pressure, the type of chemical additive, and the area ratio of Pt co-catalyst patterns to the surface area of the TiO2photoanode, were varied to generate a larger gas volume with the water-splitting device. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) semiconducting optical absorbers for photocatalytic applications have gained significant attention due to their unique physicochemical properties. Using density functional theory simulations, this study explores the M 2 Te 5 (M = Al, In) monolayer, highlighting its potential as a robust optical absorber semiconductor for overall water splitting. Detailed analysis of the structural and electronic characteristics of these materials offers crucial insights into their photocatalytic potential. The study reveals that M 2 Te 5 has an optimal band gap, favorable band edge positions, and high charge carrier mobility and transfer efficiency, essential for effective photocatalytic water splitting. The material also shows sufficient driving forces for the photoexcited carriers, particularly in facilitating the hydrogen evolution reaction under acidic conditions. Additionally, these monolayers exhibit impressive mechanical, dynamical, and thermal stabilities, with notable corrosion-resistant properties of In 2 Te 5 against photoinduced effects. [ABSTRACT FROM AUTHOR]

3D printing has attracted the interest of researchers due to its creative freedom, low cost, and ease of operation. Because of these features, this technology has produced different types of electroanalytical platforms. Despite their popularity, the thermoplastic composites used for electrode fabrication typically have high electrical resistance, resulting in devices with poor electrochemical performance. Herein, we propose a new strategy to improve the electrochemical performance of 3D-printed electrodes and to gain chemical selectivity towards glucose detection. The approach involves synthesising a nanostructured gold film using an infrared laser source directly on the surface of low-contact resistance 3D-printed electrodes. The laser parameters, such as power, focal distance, and beam scan rate, were carefully optimised for the modification steps. Scanning electronic microscopy and energy-dispersive X-ray spectroscopy confirmed the morphology and composition of the nanostructured gold film. After modification, the resulting electrodes were able to selectively detect glucose, encouraging their use for sensing applications. When compared with a gold disc electrode, the gold-modified 3D-printed electrode provided a 44-fold current increase for glucose oxidation. As proof of concept, the devices were utilised for the non-enzymatic catalytic determination of glucose in drink samples, demonstrating the gold film's catalytic nature and confirming the analytical applicability with more precise results than commercial glucometers. [ABSTRACT FROM AUTHOR]

The article discusses the 70th anniversary celebrations of CERN, a European research center for particle physics. The center has made significant scientific discoveries and technological innovations over the years. The anniversary program includes various events and activities to highlight these achievements. The article also mentions the installation of the FAIR accelerator machine and the development of compact power plants for green hydrogen production. Additionally, the article discusses three different research projects in the fields of energy storage systems, quantum photonics, and astronomical measurements. These projects are conducted by various research institutions and funded by different organizations. The European Commission and the Swiss State Secretariat for Education, Research, and Innovation are funding a project called RF 2.0, which aims to reduce the energy consumption of particle accelerators. The project takes a comprehensive approach to reducing energy consumption and aims to operate accelerators with renewable energy and minimal environmental impact. The research findings will also benefit other energy-intensive sectors such as healthcare and industry. [Extracted from the article]

Although bismuth vanadate (BiVO4) photoanode has been widely used, the solar‐driven oxygen evolution reaction (OER) performance is constrained due to the substantial bulk recombination and poor mobility of charge carriers. Herein, a facile solvothermal post‐treatment approach that employs N,N‐dimethylformamide (DMF) is developed to induce a VO4 vacancy gradient from bulk to surface of BiVO4 film, which not only improves the charge diffusion but also establishes an advantageous upward band gradient to promote the bulk hole transport. Under Air Mass 1.5 Global (AM1.5G) simulated solar illumination, the optimized BiVO4 photoanode with a VO4 vacancy gradient (denoted as B(VO)1‐δ) exhibits excellent OER performance with a charge separation efficiency of 74.4% at 1.23 V versus reversible hydrogen electrode (RHE) and incident‐photon‐to‐current conversion efficiency of 30.7% at 445 nm, 1.2 and 1.4 times higher than that of the pristine BiVO4, respectively. After loading nickel‐iron hydroxyl oxide (NiFeOOH) as a cocatalyst, the photocurrent density of B(VO)1‐δ escalates to 5.92 mA cm−2 in a hole scavenger (Na2SO3) solution and 5.07 mA cm−2 in a potassium borate buffer solution at 1.23 V versus RHE, far superior to the pristine BiVO4. This work highlights that the gradient‐tuned VO4 vacancies can effectively modulate the bulk band structure and charge transfer in BiVO4 photoanode, providing a new strategy for boosting solar water splitting performance. [ABSTRACT FROM AUTHOR]

In this paper, a CuSCN hole transport layer (HTL) is introduced between BiVO 4 and NiFeO x oxygen evolution cocatalyst (OEC) to form BiVO 4 /CuSCN/NiFeO x photoanode. Characterization and DFT calculations suggest that the high PEC performance is attributed to the incorporation of CuSCN as a HTL, which effectively facilitates charge transfer and accelerates the water oxidation kinetics, resulting in an enhanced PEC water splitting performance (5.65 mA cm−2 at 1.23 V vs. RHE). [Display omitted] • BiVO 4 /CuSCN/NiFeO x photoanode prepares by inserting CuSCN between BiVO 4 and NiFeO x. • The CuSCN promotes the transfer of holes from BiVO 4 to NiFeO x OEC. • The CuSCN exhibits enhanced OER activity and accelerates water oxidation kinetics. • BiVO 4 /CuSCN/NiFeO x photoanode achieves enhanced PEC water splitting performance. Modification of oxygen evolution co-catalyst (OEC) on the surface of bismuth vanadate (BiVO 4) can effectively improve the kinetics of water oxidation, but it is still limited by the small hole extraction driving force at the BiVO 4 /OEC interface. Modulating the BiVO 4 /OEC interface with a hole transfer layer (HTL) is expected to facilitate hole transport from BiVO 4 to the OEC surface. Herein, a copper(I) thiocyanate (CuSCN) HTL is inserted between BiVO 4 and NiFeO x OEC to create BiVO 4 /CuSCN/NiFeO x photoanode, resulting in a significant enhancement of photoelectrochemical (PEC) water splitting performance. From electrochemical analyses and density functional theory (DFT) simulations, the markedly enhanced PEC performance is attributed to the insertion of CuSCN as an HTL, which promotes the extraction of holes from BiVO 4 surface and boosts the water oxidation kinetics. The optimal photoanode achieves a photocurrent density of 5.6 mA cm−2 at 1.23 V versus the reversible hydrogen electrode (vs. RHE) and an impressive charge separation efficiency of 96.2 %. This work offers valuable insights into the development of advanced photoanodes for solar energy conversion and emphasizes the importance of selecting an appropriate HTL to mitigate recombination at the BiVO 4 /OEC interface. [ABSTRACT FROM AUTHOR]

Perovskite oxides, renowned for their adaptable structure and optoelectronic characteristics, hold significant potential for applications in catalysis and photoelectrochemical (PEC) processes. In this research, the preparation of praseodymium iron oxide (PrFeO3) by spin coating and the impact of incorporating a calcium (Ca) dopant on its PEC efficacy as photocathodes are investigated. Spin coating of a polymer containing sol–gel yields thin films with uniform morphology and porosity, facilitating effective semiconductor/electrolyte interactions, as characterized by scanning electron microscopy analyses. Evaluation of transient photocurrent responses reveals that introducing Ca at a 5 at% doping level significantly enhances the PEC activity of PrFeO3, resulting in an optimal photocurrent of −124 μA cm−2 at +0.43 V vs. a reversible hydrogen electrode (VRHE) under simulated sunlight conditions. This enhancement is accompanied by an incident photon‐to‐current efficiency (IPCE) of 3.8% at +0.43 VRHE and 350 nm, along with an onset potential of +1.1 VRHE. Ultraviolet and visible spectroscopy analyses indicate an increase in light‐absorption capabilities in the Ca‐doped films and a noticeable reduction in bandgap compared to the undoped counterparts, further supported by IPCE measurements. In the findings, the significant role of dopants in augmenting the photocurrent performance of stable perovskite oxides, highlighting their potential in advancing photon conversion technologies, is underscored. [ABSTRACT FROM AUTHOR]

Solar-driven CO2 reduction to yield high-value chemicals presents an appealing avenue for combating climate change, yet achieving selective production of specific products remains a significant challenge. We showcase two osmium complexes, przpOs, and trzpOs, as CO2 reduction catalysts for selective CO2-to-methane conversion. Kinetically, the przpOs and trzpOs exhibit high CO2 reduction catalytic rate constants of 0.544 and 6.41 s−1, respectively. Under AM1.5 G irradiation, the optimal Si/TiO2/trzpOs have CH4 as the main product and >90% Faradaic efficiency, reaching −14.11 mA cm−2 photocurrent density at 0.0 VRHE. Density functional theory calculations reveal that the N atoms on the bipyrazole and triazole ligands effectively stabilize the CO2-adduct intermediates, which tend to be further hydrogenated to produce CH4, leading to their ultrahigh CO2-to-CH4 selectivity. These results are comparable to cutting-edge Si-based photocathodes for CO2 reduction, revealing a vast research potential in employing molecular catalysts for the photoelectrochemical conversion of CO2 to methane. Solar-driven CO2 conversion to produce solar fuels is an attractive way to harness solar energy and reduce carbon emissions. Here, the authors report two osmium complexes as highly active and selective CO2 reduction catalysts for selective CO2-to-methane conversion on Si-based photocathodes. [ABSTRACT FROM AUTHOR]

Copper indium sulfide quantum dots (CIS QDs) possess the desired optical properties to act as photoanodic material in photoelectrochemical cells, like a high molar absorption coefficient over the entire visible spectrum and long exciton lifetimes. The already reported procedures that utilize photoanodes based on such nanoparticles, however, exploit harsh conditions or utilize non‐scalable, expensive, and low‐yield syntheses. Here, the construction of CIS QDs adsorbed onto TiO2/FTO photoanodes (FTO = fluorine‐doped tin oxide) with a process aimed at avoiding these issues is proposed. In particular, the employment of dihydrolipoic acid as the ligand allows an easy and cost‐effective functionalization. CdS layers are deposited onto the nanoparticles to enhance the photoelectrochemical properties. Full characterization of the steady–state and transient photoelectrochemical properties of the electrodes is performed to gain information on the interfacial dynamics among the different components of the electrode. Maximum IPCEs of the order of 50% and a spectral sensitization extended up to 700 nm are obtained in the optimized conditions. [ABSTRACT FROM AUTHOR]

Efficient photosensitizers are crucial for advancing solar energy conversion and storage technologies. In this study, we designed and synthesized a novel organic dye, denoted as YB6, for p‐type dye‐sensitized solar cells (p‐DSCs) and photoelectrochemical H2O2 production. YB6 features an extended conjugated π‐bridge derived from indacenodithieno[3,2‐b]thiophene and exhibits notable advantages: a two‐fold higher molar extinction coefficient at its main absorption peak and a broader absorption as compared to the PB6 dye. In p‐type dye‐sensitized NiO photoelectrochemical cells, the YB6‐based device demonstrated superior performance as compared to the PB6‐based device. It delivered nearly a 50 % higher H2O2 production over 5 hours. Furthermore, when fabricated into p‐DSCs, the YB6‐based device exhibited a 33 % higher power conversion efficiency. This enhancement is caused by suppressed charge recombination from the dye structure, which in turn may be traced to a larger thermodynamic up‐hill process for recombination losses in the YB6‐based system. [ABSTRACT FROM AUTHOR]

The high voltage required to overcome the thermodynamic threshold and the complicated kinetics of the water splitting reaction limit the efficiency of single semiconductor‐based photoelectrochemistry. A semiconductor/solar cell tandem structure has been theoretically demonstrated as a viable path to achieve an efficient direct transformation of sunlight into chemical energy. However, compact designs exhibiting the indispensable optimally balanced light absorption have not been demonstrated. In the current work, we design and implement a compact tandem providing the complementary absorption of a highly transparent BiVO4 photoanode and a PM6:Y6 solar cell. Such bandgap combination approaches the optimal to reach the solar‐to‐hydrogen (STH) conversion upper limit for tandem photoelectrochemical cells (PECs). We demonstrate that, by using a photonic multilayer structure to adequately balance sunlight absorption among both tandem materials, a 25% increase in the bias‐free STH conversion can be achieved, setting a clear path to take compact tandem PECs to the theoretical limit performance. [ABSTRACT FROM AUTHOR]

Water splitting via photoelectrochemical (PEC) cells offers a promising route to generate hydrogen fuel using solar energy. Nanostructured metal oxides have emerged as leading candidates as photoelectrodes in photocatalytic H2 production due to their photo-electrochemical stability, large surface area, earth abundance, and suitable band gap energies. This review reports the recent advancements of nanostructured metal oxide as photoanodes in photoelectrochemical (PEC) water-splitting applications. This review focuses on recent advancements in metal oxide photoanodes, their synthesis methods, modification strategies, and performance in PEC water splitting. Critical materials such as TiO2, Fe2O3, WO3, and BiVO4 are discussed in detail, highlighting their strengths, limitations, and future research directions to enhance efficiency and stability. This review will give clear insight into the trends and the critical factors for efficient metal oxide photoelectrode to improve the photocatalytic effectiveness in generating hydrogen fuel as an alternative energy source in the future. Finally, this study emphasises the potential of incorporating machine learning methods into experimental workflows to accelerate the optimisation of electrocatalysis performance, representing a significant advancement in developing efficient and sustainable hydrogen production technologies.

Polymeric carbon nitride (CN) has emerged as a promising photoanodic material in water‐splitting photoelectrochemical cells (PEC). However, the current deposition methods of CN layers on substrates usually include a long heating process at 500−550 °C, which might cause sublimation or decomposition of the CN monomers and destruction of the substrate, leading to a nonuniform CN film. Herein, a simple, fast, and scalable energy‐economic procedure to synthesize homogenous CN films is introduced. The predesigned CN monomers film is subjected for several minutes to higher temperatures than the standard calcination procedure. The short heating process allows the formation of a uniform CN layer, with excellent contact with the substrate and good activity as a photoanode in PEC. The optimal CN photoanode reaches photocurrent densities of ≈200 μA cm−2 at 1.23 versus reversible hydrogen electrode in neutral and acidic solutions and 120 μA cm−2 in a basic solution.

Conventional time-of-flight (TOF) measurements yield charge carrier mobilities in photovoltaic cells with time resolution limited by the RC time constant of the device, which is on the order of 0.1–1 µs for the systems targeted in the present work. We have recently developed an alternate TOF method, termed nonlinear photocurrent spectroscopy (NLPC), in which carrier drift velocities are determined with picosecond time resolution by applying a pair of laser pulses to a device with an experimentally controlled delay time. In this technique, carriers photoexcited by the first laser pulse are "probed" by way of recombination processes involving carriers associated with the second laser pulse. Here, we report NLPC measurements conducted with a simplified experimental apparatus in which synchronized 40 ps diode lasers enable delay times up to 100 µs at 5 kHz repetition rates. Carrier mobilities of ∼0.025 cm2/V/s are determined for MAPbI3 photovoltaic cells with active layer thicknesses of 240 and 460 nm using this instrument. Our experiments and model calculations suggest that the nonlinear response of the photocurrent weakens as the carrier densities photoexcited by the first laser pulse trap and broaden while traversing the active layer of a device. Based on this aspect of the signal generation mechanism, experiments conducted with co-propagating and counter-propagating laser beam geometries are leveraged to determine a 60 nm length scale of drift velocity dispersion in MAPbI3 films. Contributions from localized states induced by thermal fluctuations are consistent with drift velocity dispersion on this length scale. [ABSTRACT FROM AUTHOR]

Photoelectrochemical (PEC) organic conversion is a promising approach to convert low‐cost organics to value‐added chemicals, which urgently needs the development of efficient and highly selective photoanodes. Here, a Pt single‐atom dispersed WO3 amorphous/crystalline homojunction for anodic glycerol oxidation reaction (GOR) coupled with cathodic hydrogen generation is reported. In the coupled photoelectrocatalytic system, the novel Pt‐SA/WOx photoanode reaches a photocurrent density of 2.85 mA cm−2 at 1.2 V versus RHE, with up to 297.3 mmol m−2 h−1 of glycerol conversion rate and 60.2% of dihydroxyacetone (DHA) selectivity, realizing green synthesis of high‐value chemicals. The experimental data and theoretical calculations reveal the regulated band structure, build‐in electric field, and surface charge density of Pt‐SA/WOx, which can improve the carrier lifetime, accelerate charge transfer, and reduce the energy barrier for the GOR process, thus boosting PEC activity and DHA selectivity. This work provides a feasible plan for designing atomic‐level engineering and constructing amorphous/crystalline homojunction on photoanodes for efficient PEC high‐value products from biomass. [ABSTRACT FROM AUTHOR]

Photoelectrochemical solar to hydrogen conversion is a promising approach to solve energy and environmental problems. One of the paramount challenges to overcome is to achieve high solar to hydrogen efficiency while retaining stable service behavior without photocorrosion of the photoanode. In this study, a hydrogel‐enabled dual‐shielding (FeCoOx/PAAM) strategy is reported to improve efficiency and suppress photocorrosion of photoanode during solar water splitting especially in a high‐intensity illumination. Anodic photocorrosion of BiVO4 photoanodes involves the chemical and physical construction changes under the conditions of light field, electric field, and electrolyte. The utilization of FeCoOx/PAAM on BiVO4 inhibits the improvement of oxygen evolution reaction kinetics, bubble dynamics, and blocking ion dissolution diffusion, which effectively suppresses anodic photocorrosion and simultaneously improves efficiency of BiVO4 photoanode. The improved BiVO4/FeCoOx/PAAM photoanode shows a superior photocurrent density of 19.88 mA cm−2 at 1.23 V versus RHE, and a high charge separation efficiency of 98% with enhanced stability over 60 h (300 mW cm−2). This study contributes to developing a universal method of photoanode protection to anti‐photocorrosion, facilitating the development of high‐efficiency, high‐stability, and pollution‐free hydrogen production. [ABSTRACT FROM AUTHOR]