To accelerate the industrial application of hydrogen (H2) and support the global energy transition, seawater electrolysis emerges as a promising strategy to address energy demands and freshwater scarcity. Owing to its natural abundance and high ionic conductivity, seawater represents an attractive electrolyte resource. However, its complex chemical composition introduces significant challenges, including sluggish kinetics, catalyst poisoning, chlorine evolution, membrane degradation, and long-term corrosion. Recent years have witnessed significant progress in electrocatalyst development, electrolyzer design, and mechanistic understanding aimed at overcoming these seawater-specific constraints. In this review, we provide a comprehensive and critical overview of advances in seawater electrolysis, covering electrocatalyst design strategies for the hydrogen evolution reaction, oxygen evolution reaction, and bifunctional reactions, as well as developments in device architectures and operations. Emphasis is placed on scalable synthesis, stability under real seawater conditions, and theoretical insights from density functional theory calculations into reaction pathways and degradation mechanisms. In addition, key challenges related to standardized testing protocols, system integration with renewable energy sources, and techno-economic viability are discussed. Finally, future perspectives are outlined to guide the design of durable, scalable, and economically feasible seawater electrolysis systems, highlighting critical research directions to accelerate the transition toward large-scale green H2 production.

GaAs heterojunction solar cells with carrier-selective contacts are emerging as a promising alternative to traditional homojunction GaAs solar cells, offering low-cost fabrication, elimination of complex semiconductor doping processes, and high efficiency potential. Despite significant progress, the performance of GaAs heterojunction solar cells remains constrained by nonradiative recombination and processing issues, particularly for devices with a hole-selective contact. In this work, using SCAPS-1D simulations of the GaAs/CuO/PEDOT:PSS structure, we show that undoped GaAs with a thickness of similar to 1.5 mu m, combined with a 2 nm CuO layer, maximizes J sc, V oc, fill factor, and overall efficiency. Guided by these simulations, we experimentally show that an ultrathin (2 nm) CuO layer deposited by plasma-enhanced atomic layer deposition is an effective hole-selective contact for GaAs heterojunction solar cells. X-ray and ultraviolet photoelectron spectroscopy show favorable band alignment at the CuO/GaAs interface, with a low valence band offset (0.11 eV) and large conduction band offset (0.52 eV), confirming its electron-blocking and hole-selective behavior. The CuO layer increases V oc, J sc, fill factor, and overall efficiency from 8.6% to 13.5%. Power loss analysis indicates that optical losses are the primary contributors, suggesting a clear approach to achieving higher efficiencies.

This work leverages the multifunctionality of phytic acid to successfully synthesize a bimetallic phosphide/ nitrogen-doped carbon (CoFeP-NC) composite catalyst. Phytic acid serves three key functions: First, its six phosphate groups strongly chelate transition metal ions, forming a 3D cross-linked network that prevents metal aggregation during high-temperature carbonization, generates new phosphide active centers, and may optimize the local coordination environment by elevating the oxidation state of metal sites, boosting catalytic activity. Second, it acts as an etchant, regulating material structure to create a hierarchical porous architecture that facilitates mass transport and charge transfer during reactions. Third, the carbon coating wrapped around the phosphide is expected to inhibit the corrosion of the active components and enhance stability. Benefiting from these structural and compositional advantages, CoFeP-NC exhibits excellent activity for both oxygen reduction reaction (ORR, E1/2 = 0.86 V) and oxygen evolution reaction (OER, Ej = 10 = 280 mV). More importantly, the liquid Zinc-air batteries (ZABs) assembled using CoFeP-NC demonstrates excellent long-term durability, operating stably for approximately 5600 h, surpassing most previously reported systems. The battery also achieves a peak power density of 204 mW cm-2, with the quasi-solid-state battery reaching a power density of 538.7 mW cm-2, capable of powering devices such as LED lamps, highlighting its broad application potential. This work offers a simple and feasible strategy for constructing stable bifunctional electrocatalysts.

Aqueous zinc-ion batteries are regarded as energy storage devices with excellent development prospects, attributed to their high theoretical capacity, low cost, and favorable safety profile. Nevertheless, challenges such as severe dendrite and hydrogen evolution reactions on the zinc anode have significantly hindered the practical applications of aqueous zinc-ion battery devices. In this study, a Bi2S3-NC composite artificial interfacial layer was fabricated on the surface of the zinc electrode to modulate the thermodynamics and kinetics of zinc ion deposition/stripping reactions, thereby enabling a stable zinc anode. The experimental findings indicated that the hydrophobic Bi2S3-NC composite artificial interfacial layer could effectively suppress the occurrence of side reactions. Simultaneously, it regulated the desolvation ability of zinc ions and reaction kinetics, significantly reducing the nucleation energy barrier for zinc (the nucleation overpotential at a current density of 2mAcm-2 decreased from 87.1mV to 32.2mV), thereby facilitating uniform zinc ion deposition. Ex-situ scanning electron microscopy (SEM) and in-situ optical microscopy characterizations further confirmed that the Bi2S3-NC protective layer could effectively inhibit the growth of zinc dendrites. Consequently, the modified Bi2S3-NC@Zn symmetric cell could cycle for more than 3200h under the conditions of 2mAcm-2 and 0.5 mAh cm-2, and the overpotential was also significantly reduced (from 88.5mV to 29.8mV). Meanwhile, the Zn//Cu half-cell assembled with Bi2S3-NC@Zn could still maintain a coulombic efficiency of 99.69% after 270 cycles. Additionally, the full cell assembled with Bi2S3-NC@Zn and an Mn2V2O7 cathode also demonstrated outstanding cycling stability (retained 115.7 mAh g-1 after 1400 cycles at 0.5Ag-1), far exceeding the 64.3 mAh g-1 of the bare Zn cell. This study proposes a simple and effective modification strategy for zinc anodes, providing a reference for the multi-dimensional improvement of zinc anode performance.

Transition metal-based multi-metallic carbides are promising electrocatalysts for hydrogen evolution due to their catalytic properties. Synthesis is challenging due to agglomeration, scalability limits at high temperatures, and impurities. This study introduces a room-temperature, one-step magnetron co-sputtering technique to fabricate NiMoC electrocatalysts, achieving uniform carbon deposition with Ni and Mo. Integrating a carbon magnetron source with transition metals forms unique bonds, with controlled composition and thickness, enhancing catalytic performance. NiMoC demonstrates outstanding performance in alkaline conditions, with overpotentials of 26 mV at 10 mA cm- 2 and stability over 10 days. This represents that introducing a separate carbon source during magnetron co-sputtering improves NiMoC overpotential by 62.8 % at 10 mA cm- 2 compared to NiMo. These enhancements stem from Mo2C and NiMo active sites, and improved conductivity and stability from disordered and graphite-like carbon. Sputtered NiMoC exhibits remarkable performance across pH levels, with 42 mV overpotential at 10 mA cm- 2 and stability over 70 h in acidic conditions. When integrated into a zero-gap electrolyser, NiMoC achieves excellent cell voltages of 1.78 V at 0.5 A cm-2 and 1.87 V at 1 A cm- 2, maintaining stability for 68 h. These findings highlight magnetron co-sputtering's potential for room-temperature synthesis of multi-metallic carbides, advancing energy conversion.

Perovskite-based photovoltaic systems are at the forefront of innovative methods to facilitate solar fuel generation, particularly H2 generation via overall water splitting, thanks to their high photovoltage and potential for substantial solar-to-hydrogen (STH) efficiency. Despite successful encapsulation strategies employed in solar cells to enable the practical implementation of perovskite materials, the stability of perovskite-based photoelectrodes remains a significant bottleneck, restricting viable H2 production. Moreover, the intricate electrical connections and reliance on expensive noble metals hinder the pursuit of cost-effective H2 production using perovskite-based devices. In this study, we introduce a dual-absorber perovskite/Si tandem structure encapsulated with a NiFe alloy catalyst grown on Ni foil to create a monolithic photoanode. This designed photoanode yielded a photocurrent of 14.21 mA cm- 2 at 1.23 V versus RHE, complemented by an onset potential of -0.5 V in an alkaline electrolyte. When combined with a cathode comprised of Ni nanowires (with a mere 46 mV overpotential at 10 mAcm- 2), the system maintained a sustained overall water splitting reaction for 45 h, achieving a stand-alone STH efficiency exceeding 14%. This pioneering dual-absorber stand-alone PEC system represents a significant step towards minimizing losses and outstripping conventional tandem PV-PEC, series PV-PEC, and series PEC configurations in terms of performance, practicality, and cost-effectiveness.

Photoelectrocatalytic (PEC) water splitting represents a highly ideal approach for the efficient conversion of solar energy into sustainable green hydrogen. Although tantalum nitride (Ta3N5) has emerged as a promising photoanode material, its performance is far below the theoretical limit. Among several photoelectrode design strategies, interfacial modification can be beneficial for suppressing interfacial charge recombination and promoting charge transfer process, which is a key focus in recent research. In the review, a brief overview of recent advances in interfacial modification strategies for Ta3N5 photoanodes and their influence on the structure-performance relationship are summarized, aiming at an in-depth understanding of the charge-transfer mechanism during PEC water oxidation, and providing insights into designing efficient and stable Ta3N5 photoanodes for solar-to-fuel conversion through photoelectrocatalysis.

Carbon-based mesoscopic perovskite solar cells (C-MPSCs) have attracted widespread attention owing to the advantages of printable fabrication and excellent stability. However, the nonradiative recombination loss at buried interfaces hinders further efficiency improvements of C-MPSCs. In the study, urea phosphate derivative is utilized as a modifier for the buried interfaces of C-MPSCs. In the mesoporous titanium dioxide (m-TiO2) layer, guanylurea phosphate (GUP) can interact with TiO2, anchoring to the surface of m-TiO2 and forming a molecular bridge at the perovskite/m-TiO2 interface. The molecular bridge facilitates the extraction of charge carriers and minimizes nonradiative recombination losses, while GUP can passivate the dangling Pb2+ and I- vacancy defects in the perovskite, respectively. Furthermore, GUP helps slow down the perovskite crystallization, promotes pore filling, reduces residual stress in the device, and optimizes energy level alignment. Consequently, the power conversion efficiency of C-MPSCs with GUP increases to 19.78%, from 18.22% of the control devices. C-MPSCs with GUP exhibit excellent stability in air storage, thermal aging, and damp heat stability tests. The study provides a novel approach to eliminate nonradiative recombination losses at the buried interfaces of C-MPSCs.

Polymeric carbon nitride (PCN), as a novel organic photocatalyst, has demonstrated promising application potential in photoelectrochemistry due to its unique physicochemical properties. However, its narrow light absorption range and poor charge separation have severely hindered its practical application. In this study, a crystalline 2D heptazine-based carbon nitride (poly(heptazine imide)) and tin disulfide (PHI/SnS2) heterojunction is constructed in situ on a conductive substrate (FTO) by a combination of electrochemical deposition and chemical vapor deposition to solve the above limitations of PCN. The experimental results show that the formation of the heterojunction significantly broadens the light absorption spectrum and enhances the charge separation efficiency, thereby improving the photoelectrochemical performance. Under a bias voltage of 1.23 V vs. RHE, the photocurrent density of the PHI/SnS2 photoanode reaches ca. 880 mu A cm-2, approximately 29 times higher than that of pure PCN. The incident photon-to-current conversion efficiency (IPCE) of PHI/SnS2 at a wavelength of 380 nm reaches 41.5%. This work represents an important advancement in the rational design and synthesis of CN-based photoanodes with high photoelectrochemical performance.

High-quality perovskite films are crucial for achieving efficient carbon-based printable mesoscopic perovskite solar cells (MPSCs). However, rapid crystallization leads to poor film quality and the formation of defects, resulting in severe non-radiative recombination that hinders the improvement of device performance. In this work, an organic small molecule, dicyandiamide (DCDA), with multifunctional groups was incorporated into the perovskite precursor solution to concurrently regulate crystallization and manage defects in the perovskite in the mesoporous scaffold, and high performance MPSCs were obtained. Due to the robust interactions of the -C 00000000 00000000 00000000 00000000 11111111 00000000 11111111 00000000 00000000 00000000 N and -CN groups in DCDA with un-coordinated Pb2+, and/or FA+/MA+via hydrogen bonding, coupled with the -NH2 groups of DCDA forming hydrogen bonding or electrostatic interactions with halide anions to inhibit ion migration, the defects were passivated. The introduction of DCDA effectively retarded nucleation and grain growth, and significantly reduced the film formation rate. Thus, perovskite films with larger grain sizes, preferred orientation, and lower trap state density were obtained, thereby greatly suppressing non-radiative recombination. As a result, the average power conversion efficiency (PCE) of MPSCs treated with DCDA was improved from 17.15 +/- 0.48% to 18.75 +/- 0.42%, and a champion PCE of 19.12% was obtained. Meanwhile, the PCE of unpackaged MPSC devices still remained at 94.00% of the initial efficiency when stored in an air environment after 103 days, demonstrating excellent stability. The strategy facilitates a deeper understanding of perovskite crystallization in printable MPSCs.

Restoring ammonia from waste nitrate stands as a promising strategy for reducing reliance on the energy-intensive Haber-Bosch process and tackling environmental pollutants. Advancing the catalytic aspects of photoelectrochemical (PEC) ammonia synthesis via waste nitrate reduction is of great importance to enhance its viability for sustainable chemical production. However, this process still suffers from low ammonia faradaic efficiency (FE) with high operational potential due to its involvement in multi-electron reactions. Herein, we integrated a cobalt-doped TiOx (Co-TiOx) cocatalyst and Ag nanowires (NWs) electron extraction layer onto TiOx/CdS/Cu2ZnSnS4 (CZTS) photocathode, achieving nearly 100 % ammonia FE and an onset potential of similar to 0.49 V vs. RHE. Evidenced by the in-situ synchrotron-radiated FTIR (SR-FTIR) and theoretical calculations, the increased ratio of surface oxygen vacancy sites (Vo) induced by Co-TiOx is crucial for the key reaction intermediates adsorption (i.e. *NO3 and *NO2) for subsequent ammonia production. Moreover, the transparent Ag NWs facilitates the electron extraction from TiOx/CdS/CZTS to the surface catalytic sites. Powered by CZTS solar cells, a standalone solar-to-ammonia system has been demonstrated with outstanding activity and catalytic performance.

In pursuit of efficient water-splitting technologies, the development of high-performing electrocatalysts is crucial, particularly for the hydrogen evolution reaction (HER). In addition, it is paramount to adopt cost-effective approaches that leverage earth-abundant metals, together with scalable synthesis methods. In this study, we introduce a synthesis approach that combines a facile solution corrosion technique with plasma modification, thereby enhancing the hydrogen evolution activity of NiMo alloys. The inclusion of NH3 plasma modification plays a dual role by concurrently reducing and nitriding as-synthesized NiMo hydroxide. The treatment results in a significant reduction in the HER overpotential to 95 mV at 10 mA/cm(2) compared to its initial overpotential. This improvement is attributed to enhanced kinetics due to substantial reductions in charge transfer resistance and an increased double-layer capacitance. Furthermore, the catalyst demonstrates excellent stability of close to 120 h, thereby highlighting the potential of this synthesis method for large-area synthesis of HER electrocatalysts.

The quest for net-zero emissions highlights the significance of hydrogen as a clean energy carrier, necessitating efficient production methods. Electrochemical water splitting emerges as a crucial method for hydrogen generation, with its further advancement hinging on the development of effective bifunctional catalysts that are efficient in both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). In this study, we develop the bifunctional electrocatalyst NiFe(OH)(x)/Fe/graphene through a simple solution-corrosion approach. The overpotentials required for OER and HER to achieve a current density of 10 mA cm(-2) are 237 and 42 mV, respectively, while the overall water splitting occurs at a low cell voltage of 1.51 V for the same current density. Remarkably, the catalyst displays robust stability exceeding 70 h at 20 mA cm(-2) in 1 M KOH. When scaled to 10 x 10 cm(2), its performance is comparable to that of a smaller size 0.5 x 0.5 cm(2) electrode, indicating the scalability of our method and potential for industrial-scale hydrogen production. Trace incorporation of iron and the facilitation by graphene modify the electronic structures and coordination environment in the amorphous NiFe(OH)(x)/Fe/graphene composite. This alteration enhances the distribution of active sites and reduces kinetic barriers for both HER and OER, thereby increasing its bifunctional catalytic activity. This study not only introduces a novel catalyst design that incorporates in-situ Fe metal powder within OER-active catalysts to generate HER active sites for enabling bifunctionality, but also offers a pathway to manufacture high performance electrocatalysts for industrial applications.

The broad-band self-trapped exciton (STE) emission feature of lead-free halide double perovskites makes it challenging to realize emission with various wavelengths in a single material. Cs2NaInCl6:Sb3+ crystals with blue emission (440 nm) were synthesized by rationally introducing the Sb3+ ion into Cs2NaInCl6 with a photoluminescence quantum yield (PLQY) up to 99.35%. The Ln(3+) (Tb3+ and Ho3+) ions were doped into Cs2NaInCl6:Sb3+ to achieve spectrally tunable emission from blue to green and pink emission owing to the energy transfer from the host STE to Ln(3+) ions, with PLQY values of 90.68% and 61.87%, respectively. By carefully adjusting the doping level of Ln(3+) ions, white light emission with a PLQY of 68.87% was achieved in the Tb3+ and Ho3+ co-doped Cs2NaInCl6:Sb3+ system. LED devices based on Sb3+/Ln(3+) co-doped Cs2NaInCl6 with multicolor and white light emissions were fabricated based on these phosphors, which exhibit excellent spectral and environmental stability. The results show that double perovskite luminescence materials have potential for application in solid-state lighting and multi-color displays.

Extending the photoresponse into the near-infrared region (NIR) is an urgent research topic in perovskite solar cells. A ternary bulk heterojunction (BHJ) layer composited with PC61BM, D18-Cl and Y6 was deposited onto the perovskite to broaden light absorption. The ternary BHJ layer can absorb low-energy photons in the NIR region (800-920 nm) and generate excitons. Subsequently, these excitons dissociate into free electrons and holes at the donor-acceptor interface, thus extending the device's photo response up to 920 nm. Moreover, due to the good electron transport capabilities of the acceptors Y6 and PC61BM in the BHJ film, the BHJ layer also acts as the electron transport layer in the inverted PSC device. The inverted P-I-N device based on perovskite/BHJ achieved an external quantum efficiency (EQE) up to 30% in the near-infrared range. Compared to control PSCs, the short-circuit current (JSC) increased from 21.64 to 24.35 mA cm-2, resulting in a high PCE of 19.88%. Additionally, the high hydrophobic surface of the ternary layer contributes to the good long-term stability of the device. The results demonstrate that the ternary organic bulk heterojunction is an effective strategy for achieving efficient light utilization in the near-infrared region and enhancing power conversion efficiency in perovskite solar cells.

Crucial advancements in versatile catalyst systems capable of achieving high current densities under industrial conditions, bridging the gap between fundamental understanding and practical applications, are pivotal to propel the hydrogen economy forward. In this study, vertically oriented hierarchically multiscale nanoflakes of NiFeCo electrocatalysts are presented, developed by surface modification of a porous substrate with nano-structured nickel. The resulting electrodes achieve remarkably low overpotentials of 139 mV at 10 mAcm-2 and 248 mV at 500 mAcm-2. Further, scaled-up electrodes are implemented in a water-splitting electrolyser device exhibiting a stable voltage of 1.82 V to deliver a constant current density of 500 mA cm-2 for over 17 days. Moreover, the role of the unique structures on electrochemical activity is systematically investigated by fractal analysis, involving computation of structure factors such as Minkowski connectivity, fractal dimension, and porosity using scanning electron microscope images. It is found that such structures offer higher surface area than typical layered double hydroxide structures due to morphological coherence that results in a superhydrophilic surface, while the base Ni layer boosts the charge transfer. This study demonstrates a Ni/NiFeCo(OH)x heterostructure with highly porous morphology, a key to unlocking extremely efficient oxygen evolution reaction activity with exceptional stability. Moreover, fractal analysis is presented as a valuable tool to evaluate the electrochemical performance of catalysts for their structured morphology. The research presents vertically aligned nanoflakes of electrocatalyst, which exhibit a hierarchical multiscale structure. These nanoflakes significantly boost the electrochemical surface area, resulting in highly efficient water oxidation reactions with elevated current densities. Fractal analysis that provides crucial information about role of these structures toward performance enhancement and guide toward optimization of synthesis methods that achieve such structures is employed.image

As a metal-free semiconductor photoelectrode material, polymeric carbon nitride (CN) has become one of the research hotspots in the field of photoelectrochemical (PEC) water splitting due to its unique physical and chemical properties. However, high onset potential (V-onset) seriously hinders PEC properties and utilization of solar energy. Herein, boron or phosphor-doped polymeric carbon nitride (CN-B/P) films are successfully prepared by combining close-spaced thermal copolymerization with a simple drip coating-heat treatment method. As a photoanode material, the as-synthesized doped-CN films exhibit excellent performance with improved charge injection properties, a longer electron lifetime and reduced flat band potential. Consequently, the photocurrent density of CN-B/P is increased by about 1-3 times compared with pure carbon nitride samples. More importantly, the CN-B and CN-P photoanode both exhibit a very negative V-onset of about 0 V versus reversible hydrogen electrode, which is comparable with the state-of-the-art metal-based photoanodes.

Solar energy conversion devices with charge-selective contacts are attracting significant research interest as a cost-effective alternative to homojunction counterparts. This study presents a novel approach for fabricating high-performance solar cells based on InP heterojunctions using a solution-processed ferri-hydrite (Fh) electron-selective contact (ESC). The champion cell efficiency of 16.6% is achieved, which is a significant improvement over those from previous studies using other solution-processed ESC materials. X-ray photoelectron spectroscopy measurements showed that the low conduction band offset at the Fh-InP interface facilitated selective transport of photogenerated electrons from InP. Moreover, the Fh electron-selective contact layer provided an excellent photoelectrochemical half-cell water reduction efficiency of 8.4%. The Fh layer not only selectively extracts photogenerated electrons from InP but also simultaneously serves as a surface protection layer, improving the cell's long-term stability. These results demonstrate the potential of Fh as a low-cost and easily fabricated material for use in high-efficiency photovoltaic and photoelectrochemical devices. Our findings pave the way for further improvements in the efficiency of InP heterojunction solar cells by addressing the losses incurred in the cells.