Stable Hydrogen Production Research Articles

N, S, P co-doped Co/Co3O4/C particles on carbon fiber paper as a self-supported bifunctional catalyst for direct seawater splitting

To optimize the distribution and transportation of electrical energy, converting surplus or low-quality electricity through electrocatalytic seawater splitting to produce hydrogen is an ideal method. In this work, we developed a bifunctional electrocatalyst (ZIF-9/CP-S-P) through the in-situ growth of ZIF-9 on the carbon fiber paper (CP), followed by sequential sulfurization and phosphidation. This catalyst achieves stable hydrogen and oxygen production in natural seawater, displaying outstanding oxygen evolution activity with an overpotential of just 390mV at 10mA/cm² (Tafel slope: 426.5mV/dec) and impressive hydrogen evolution activity with an overpotential of only 578mV at 10mA/cm² (Tafel slope: 287.7mV/dec). The two-electrode electrolyzer assembled by ZIF-9/CP-S-P || ZIF-9/CP-S-P was conducted the chronoamperometry test for 20000s in 1M phosphate buffer solution and for 100000s in natural seawater, and its performance was comparable to that of commercial Pt/C || IrO2. These findings indicate the potential of ZIF-9/CP-S-P catalyst for practical applications in direct seawater splitting to produce hydrogen and oxygen.

Innovative Strategies for Combining Solar and Wind Energy with Green Hydrogen Systems

The integration of wind and solar energy with green hydrogen technologies represents an innovative approach toward achieving sustainable energy solutions. This review examines state-of-the-art strategies for synthesizing renewable energy sources, aimed at improving the efficiency of hydrogen (H2) generation, storage, and utilization. The complementary characteristics of solar and wind energy, where solar power typically peaks during daylight hours while wind energy becomes more accessible at night or during overcast conditions, facilitate more reliable and stable hydrogen production. Quantitatively, hybrid systems can realize a reduction in the levelized cost of hydrogen (LCOH) ranging from EUR 3.5 to EUR 8.9 per kilogram, thereby maximizing the use of renewable resources but also minimizing the overall H2 production and infrastructure costs. Furthermore, advancements such as enhanced electrolysis technologies, with overall efficiencies rising from 6% in 2008 to over 20% in the near future, illustrate significant progress in this domain. The review also addresses operational challenges, including intermittency and scalability, and introduces system topologies that enhance both efficiency and performance. However, it is essential to consider these challenges carefully, because they can significantly impact the overall effectiveness of hydrogen production systems. By providing a comprehensive assessment of these hybrid systems (which are gaining traction), this study highlights their potential to address the increasing global energy demands. However, it also aims to support the transition toward a carbon-neutral future. This potential is significant, because it aligns with both environmental goals and energy requirements. Although challenges remain, the promise of these systems is evident.

Ultrafine Pd nanoparticles confined in naphthalene-based covalent triazine frameworks for efficient and stable hydrogen production from formic acid

Formic acid (FA) is considered as a kind of promising hydrogen storage materials due to its economic feasibility, safety, stability and high hydrogen density. Nevertheless, it is a challenge to design a high-performance catalyst with high activity, selectivity and stability for the dehydrogenation of FA to generate hydrogen (H2). Herein, a range of covalent triazine frameworks (CTFs including 1,8-CTF, 1,5-CTF and 2,3-CTF) with abundant nitrogen atoms are developed to support palladium nanoparticles for efficiently catalyzing FA dehydrogenation. Ultrasmall palladium nanoparticles with a size of 1.2 ± 0.3 nm showed near 100 % H2 selectivity and high catalytic activity in FA dehydrogenation supported by 1,8-CTF. The activation energy of FA dehydrogenation catalyzed by Pd/1,8-CTF reaches 26.17 kJ·mol−1. In addition, Pd/1,8-CTF exhibits high stability and easy recyclability, and the catalytic activity is maintained even after 6 cycles. This work gives a feasible strategy to develop high-efficiency and selective nanocatalysts for H2 production from FA dehydrogenation.

Investigation into the electrolysis performance of a novel directly solar irradiated solid oxide electrolysis cell

Current coupling methods linking solar energy to solid oxide electrolysis cell (SOEC) mostly involve indirect coupling, with limited studies exploring direct coupling. This study is the first to evaluate a novel directly solar irradiated solid oxide electrolysis cell, anticipating a reduction in polarization loss incurred during the electrolysis process and improving the electrochemical performance of the system through direct solar irradiation. Additionally, it aims to reduce electric energy consumption required to maintain the high-temperature environment for the reaction and enhance the energy conversion efficiency of the electrolysis system, presenting a unique coupling technology. Hence, this paper proposes and develops the inaugural solar SOEC system, directly harnessing sunlight on the SOEC electrode surface, achieving stable and continuous hydrogen production through experimental methods. Experimental results demonstrate that direct solar irradiation increases the SOEC system’s heating rate by 12 times compared to electric heating, with a notably swifter response time. Under identical electrolysis voltages, the system exhibits significantly higher efficiency under direct solar irradiation than under electric heating. Moreover, for equivalent hydrogen production, the total energy input from solar energy is lower than that from electric heating, saving about 76 % of energy. Under specific conditions—solar radiation power of 123.2 W, electrolysis temperature of 655 °C, cathode-side gas input maintaining a water-hydrogen molar ratio of 8:2, and an electrolysis voltage of 1.5 V—the SOEC system sustains a nearly constant current density of about 359 mA/cm2 for 3 h. Comparative experiments conducted under identical working conditions, both in solar and electrically heated environments, reveal that the electrochemical impedance spectroscopy indicates inhibited mass transfer processes during electrolysis under direct solar irradiation. Consequently, the electrochemical performance of the SOEC system operating under direct solar irradiation was lower than that under electrically heated environments, across varying electrolysis temperatures and water contents. This study uncovers the pivotal influence of direct solar irradiation on concentration losses during the electrolysis process. The corresponding concentration losses can be subsequently mitigated by optimizing the reactor structure of the solar SOEC system.

Enhanced stability in Co0.8Ni0.2/NDMCS catalysts: Carbon nitride encapsulation for robust hydrogen generation

Catalytic hydrolysis of NaBH4 is a promising method for "on-demand" hydrogen generation, with cobalt catalysts playing a key role due to their high hydrogen generation rates. However, rapid cobalt dissolution and poor recycling hinder stable hydrogen production. This study presents a dual-mode stabilization technique using carbon nitride encapsulation to address these challenges. Co0.8Ni0.2 alloy nanoparticles (NPs) are confined within N-doped mesoporous carbon spheres (NDMCS) and encapsulated with a carbon nitride shell (∼ 5 nm thick). XPS results reveal strong non-classical metal-support interaction, increasing activation energy from 38.82 to 44.6 kJ mol−1, which controls cobalt's reactivity, leading to excellent recycling efficiency (90 % retention of initial rate, no change in particle size) in high-concentration reactants (2 %NaBH4 + 2 %NaOH). The retention rate drops to 26.8 % without this stabilization due to rapid metal dissolution. This stability of Co0.8Ni0.2 alloy in alkaline conditions has significant practical implications for hydrogen generation and other electrochemical applications.

Dual Hydrogen Production System: Synergistic Effect of Ru and Ce Over Cu2O Nanotubes Drives Hydrogen Evolution and Formaldehyde Oxidation.

Water splitting for hydrogen production is limited by high cell voltage and low energy conversion efficiencies due to the slow kinetic process of the oxygen evolution reaction (OER). Here, an electrolytic system is constructed in which the cathode and anode co-release H2 at ultra-low input voltage using formaldehyde oxidation reaction (FOR) instead of OER. The prepared RuCe co-doped Cu2O nanotubes on copper foam (RuCe-Cu2O/CF) are used as electrode materials for the HER-FOR system. A current density of 0.8 A cm-2 is achieved at 0.55V, and a stable hydrogen production process is realized at both the cathode and anode. Density functional theory (DFT) studies show that the synergistic effect of Ru and Ce drives: i) the d-band center of RuCe-Cu2O/CF away from the Fermi energy level; ii) the energy barrier for the C─H cracking of the H2C(OH)O* intermediate in FOR is lowered, which promotes the formation of H2 from H*, and iii) ΔGH* tends to 0 (-0.1eV), optimizing the reaction kinetics of HER. This work provides a new design for an efficient catalyst for dual hydrogen production systems from water splitting.

Investigation of simultaneous production of H2 and separable carbon from CH4 in a fluidised bed of NiO/Ca2Fe2O5/CaO particles

This work investigated the possibility of simultaneous production of hydrogen/syngas and separable solid carbon in a fluidised bed by using CH4-CO2 cycles and exploring the carbon growth over solid catalytic particles of NiO/Ca2Fe2O5/CaO. This two-stage process included i) stage I: H2-rich gas and carbon were simultaneously generated from the interaction between CH4 and NiO/Ca2Fe2O5/CaO particles; and ii) stage II: the reduced/carbon-deposited particles were regenerated in CO2. Following our previous successful demonstration of the process for stable hydrogen production over cycles, this study focused on the formation of solid carbon and aimed at understanding its growth mechanism as well as demonstrating the potential of using fluidisation as a means of automatic carbon separation. By tracking the carbon growth history and the change in phases of the reacted NiO/Ca2Fe2O5/CaO particles at temperatures from 700 to 900 °C, we discovered the formation of various forms of nano-structured carbon from CH4 conversion (e.g. partial oxidation, pyrolysis). These include carbon nanotubes (CNTs), carbon graphite sheets, carbon onions (CNOs), and carbon fibres. Amorphous carbon was also observed, particularly in the initial stage of CH4 conversion. Higher temperatures like 800 °C and 900 °C gave faster kinetics of CH4 conversion and more formation of solid carbon. Fe3C phase was observed on the reduced catalytic particles and could act as an intermediate phase or carbon sink for carbon growth. The results suggested that other mechanisms for carbon deposition, such as directly over Fe sites, may also exist. Fluidisation with a higher U/Umf ratio separated more carbon-rich fines from the bulk catalytic particles in the fluidised bed. Fluidising with air at 700 °C effectively removed amorphous carbon on the reacted catalytic particles, whilst structured carbon remained. Full separation and purification to obtain pure carbon require furthers optimisation of e.g. fluidisation parameters and material design.

Rationally designed CaTiO3/Mn0.5Cd0.5S/Ni3C S-scheme/Schottky integrated heterojunction for efficient photocatalytic H2 evolution

Developing effective photocatalysts to achieve stable and efficient solar-induced hydrogen production remains a significant challenge due to rapid photocarrier recombination and sluggish hydrogen evolution kinetics. Here, a multi-interfacial engineering strategy involving the decoration of metallic Ni3C onto CaTiO3/Mn0.5Cd0.5S was proposed to create an S-scheme/Schottky hybrid heterostructure with multiple carrier transport paths for effective photocatalytic H2 production. Exploiting the synergy between S-scheme heterojunction and Schottky barrier, the engineered ternary CaTiO3/Mn0.5Cd0.5S/Ni3C hybrid heterojunction exhibits outstanding photostability and significantly enhanced hydrogen evolution activity of 79.1 mmol g-1 h−1, which was about 4.55, 3.22 and 2.59 times greater than Mn0.5Cd0.5S, Mn0.5Cd0.5S/Ni3C, and CaTiO3/Mn0.5Cd0.5S, respectively. By creating an S-scheme heterojunction between CaTiO3 and Mn0.5Cd0.5S, accompanied by a robust internal electric field (IEF), spatial charge separation can be effectively accelerated while ensuring the simultaneous preservation of highly active electrons and holes. Meanwhile, Ni3C nanoparticles, acting as a Schottky-junction H2 generation cocatalyst, can efficiently trap the photoinduced electrons to establish multiple charge transfer channels and supply ample active sites for photoreduction reaction, thereby further optimizing the hydrogen generation kinetics. The integration of a Schottky barrier and S-scheme heterojunction in this research is expected to offer new perspectives for designing other highly effective hybrid catalysts for solar-to-hydrogen fuel conversion.

Designing a hydrogen generation system through PEM water electrolysis with the capability to adjust fast fluctuations in photovoltaic power

—Hydrogen can be produced through water electrolysis using photovoltaic (PV) power in a way that is both pollution-free and friendly to the environment, rendering hydrogen a clean energy source. Proton Exchange Membrane (PEM) water electrolysis is an efficient hydrogen generation process because of its compact design, fast response, high efficiency and high current density. The fast fluctuations in solar power, however, are difficult for PEM water electrolysers to control effectively. To address the problems caused by intermittent power, a system for producing hydrogen consisting of a solar panel, battery, and commercial PEM electrolyser, alongside an electrical control strategy, is proposed. The Maximum Power Point Tracking (MPPT) Perturb and Observe (P&O) technique is employed for PV systems, while a bidirectional charge controller manages the charging and discharging of the battery. A Proportional-Integral (PI) controller is also utilised for the PEM electrolyser to ensure efficient operation. This setup provides a practical solution for hydrogen production. It enhances efficiency and reduces the risk of damage to the electrolyser, thereby making the process more sustainable and reliable. The proposed approach has been validated by simulation under different conditions. A comparative analysis has also demonstrated that the proposed system can perform well despite having less PV power. When comparing systems with and without batteries for energy storage, the system with the battery for energy storage has a 10% higher energy efficiency under the same operating conditions. This suggests that adding energy storage can increase energy utilization, maintain the DC link voltage constant, and achieve stable hydrogen production.

NiO/vermiculite composites prepared for photocatalytic degradation of methanol-water solution and hydrogen generation

A novel eco-friendly NiO/Vm clay based photocatalysts were synthesized from two vermiculites (Vm1 and Vm2) and nickel(II) nitrate hexahydrate (Ni(NO3)2·6H2O salt precursor by the chemical precipitation without and with the sodium hydroxide (NaOH) or ammonium hydroxide (NH4OH, 28% NH3 in H2O) as precipitation agents (Synthesis A) in comparison with the solid-state thermal decomposition (Synthesis B) at 600 °C. Structural properties of all specimens were characterized by X-ray fluorescence, scanning electron microscopy, X-ray diffraction, infrared (IR) and Raman spectroscopy. The photocatalytic performance of NiO/Vm composites was evaluated under UV radiation (λ = 254 nm) for decomposition of methanol-water to hydrogen over 4-h and the stable yield of hydrogen over the 24-h periods. The NaOH and NH4OH affected the NiO crystallite size and therefore the photocatalytic activity during 4 h. Different 2:1 layer charge of Vm1 (0.82 e−) and Vm2 (0.40 e−) and the specific surface area of Vm1 (about 43 m2/g) and Vm2 (about 34 m2/g) supported H2 yield of 628.2 μmol/gcat. and 596.8 μmol/gcat., close to 657.0 μmol/gcat. produced in the presence of commercial photocatalyst TiO2 Evonik P25. Crystalline NiO precipitated and anchored in NiO/Vm composites contained smaller crystallites than those in free NiO. Vermiculite silica surface supports coverage of NiO by hydrogen bonding to Si-OH groups influencing the geometry of the NiO crystal structure (disorder NiO(X)). The heterojunction with Si-O-Ni bonding, at which electrons transfer from Vm to NiO cause enriching electron density in NiO and favoring its photocatalytic activity. Photocatalytic hydrogen generation from methanol–water mixture at the presence of all specimens indicated the main product H2 and minimum by-products CH4 and CO. The stable hydrogen production for 24 h was confirmed only in the presence NiO/Vm1–24 while maintaining the NiO(X) in small crystallites. The thermal solid-state procedure provided the gradual dehydration of vermiculites and Ni(NO3)2·6H2O to the same amount and crystallinity of NiO in NiO/Vm1 and NiO/Vm2 composites. The results of this work confirm that vermiculites mixed layer structures with different negative layer charge play a dominant role as semiconductors for anchored NiO. The photocatalytic activity of NiO/vermiculite composites can be harnessed to treat wastewater containing organic contaminants.

Enhanced Capability of Hydrogen Evolution Photocathode by Laminated Interface Engineering of Co/MoS2 QDs/pyramid-black Si.

We present a novel and stable laminated structure to enhance the performance and stability of silicon (Si) photocathode devices for photoelectrochemical (PEC) water splitting. First, by utilizing Cu nanoparticle catalysts to work on a n+p-black Si substrate via the metal-assisted chemical etching, we can achieve the black silicon with a porous pyramid structure. The low depth holes on the surface of the pyramid caused by Cu etching not only help enhance the light capture capability with quite low surface reflectivity (<5%) but also efficiently protect the p-n junction from damage. To improve the charge migration efficiency and mitigate parasitic light absorption from cocatalysts at the same time, we drop casted quantum dots (QDs) MoS2 with the size of nanometer scale as the first layer of catalyst. Hence, we then can safely electrodeposit cocatalyst Co nanoparticles to further enhance interface transfer efficiency. The synergistic effects of cocatalysts and optimized light absorption from the morphology and QDs contributed to the overall enhancement of PEC performance, offering a promising pathway for an efficient, low cost, and stable (over 100 h) hydrogen production photocathode.

High-Surface-Area Co-Cu-B Monolithic Self-Supported Catalyst for Efficient Sodium Borohydride Hydrolysis

Sodium borohydride (NaBH4) is a nontoxic and ideal storage material for hydrogen due to its safety and high hydrogen storage capacity. In order to improve the practicality of the sodium borohydride hydrogen production system, we deposited non-precious metal catalytic materials on readily available polymer foams using a simple chemical plating method, developing a suitable 3D catalyst. Its high specific surface area enables it to produce hydrogen at a rate of up to 3.92 L min−1 g−1. Its unique structure gives the catalyst excellent durability. In addition, an efficient NaBH4-based H2 supply system was developed using this catalyst. Co-Cu-B can facilitate stable hydrogen production from NaBH4, yielding a consistent power output ranging from 0 to 100 W. This work provides a new pathway for developing high-efficiency monolithic self-supported catalysts for industrial applications.

Novel organic dibranched photosensitizers featuring spiro-fluorene for efficient hydrogen generation from water

Four new metal-free organic photosensitizers featuring either a mono-anchoring donor–π–acceptor (D–π–A) or di-anchoring donor–(π–acceptor)2 (D(–π–A)2) architecture containing a spirobifluorene or spiro[fluorene-9,9′-xanthene] central donor core was prepared. These photosensitizers were subsequently tested for their efficiency in the photocatalytic production of H2, in combination with a Pt/TiO2 catalyst. Additionally, electrochemical, photophysical, and computational studies were conducted. The computational studies were specifically carried out to ascertain the electronic distribution within the photosensitizers. The influence of the molecular design on the efficiency of H2 production was examined. The di-anchoring photosensitizers notably amplified the spectral response in the visible light region, reduce aggregation on TiO2 and enhanced charge transfer. Among the fabricated photocatalytic systems, the di-anchoring photosensitizers exhibited superior photocatalytic efficiency compared to their mono-anchoring counterparts. Among all the photosensitizers, the spiro[fluorene-9,9′-xanthene]-based di-anchoring photosensitizer X2 possessing photocatalytic system demonstrated remarkable performance, producing 406.3 μmol (10.07 mL) of hydrogen over a period of 47 h under blue light irradiation. This performance corresponds to a turnover number (TON) of 6674, a turnover frequency (TOFi) of 445 h−1, an initial hydrogen production activity (activityi) of 278140 and an apparent quantum yield (AQYi%) of 4.762. The bulky spiro[fluorene-9,9′-xanthene] component endowed the photosensitizers with photostability, as confirmed by their high hydrogen production efficiency over 152 h of extended irradiation, yielding 12.69 mL of hydrogen. This study revealed, for the first time, that the bulky spiro-fluorene structure contributes positive synergistic effects to hydrogen production. It demonstrates that dibranched photosensitizers containing spiro-fluorene are promising candidates for achieving high and stable hydrogen production activity.

Machine learning assisted prediction for hydrogen production of advanced photovoltaic technologies

The photovoltaic (PV) water electrolysis method currently stands as the most promising approach for green hydrogen production. The rapid iteration of photovoltaic technologies has significantly affected on the technical and economic evaluation for photovoltaic hydrogen production. In this work, the photovoltaic hydrogen production of three most advanced silicon photovoltaic technologies is systematically compared for the first time under the climatic conditions of the Kucha region. All-weather stable hydrogen production control system with optimal charging and discharging strategies is constructed to realize stable and efficient hydrogen energy production. Seven machine learning (ML) algorithms are used to forecast the performance in power generation and hydrogen production of a 100 ​MW photovoltaic hydrogen production and energy storage (PH-S) system throughout its operational life. The long short-term memory (LSTM) algorithm exhibits the best performance, achieving mean absolute error (MAE) of 0.0415, root mean square error (RMSE) of 0.0891, and coefficient of determination (R2) of 0.8402. In terms of cost-effectiveness, heterojunction with intrinsic thin layer (HJT) PV technology achieves the lowest levelized cost of electricity (LCOE) and hydrogen (LCOH) at 0.025 $/kWh and 6.95 $/kg, respectively. According to the sensitivity analysis, when the cost of proton exchange membrane electrolysis (PEMEC) reduced 50%, the LCOH for PH-S system decreased 21.40%. This study provides valuable insights for the practical implementation of large-scale photovoltaic hydrogen production and cost reduction in PH-S systems.

Synergistically interface networked organic–inorganic photocatalytic membrane for highly stable Cr(VI) reduction and hydrogen production

Artificial conversion technology based on solar energy is one of most strategic artificial technologies for addressing environmental hazards and energy crisis. However, micro/nano-sized particulate catalysts mostly have the drawbacks of unstable microstructure and difficult recovery, which inevitably limits the practical application of photocatalysis technology. In order to overcome the defects of most inorganic particulate photocatalysts, a novel organic–inorganic photocatalytic membrane based on highly active Bi4Ti3O12/CdS composite and polyvinylidene fluoride (PVDF) was processed for simulated sunlight (SSL)-driven Cr(VI)-to-Cr(III) (CTC) reduction and H2O-to-H2 (HTH) conversion. Due to the maximum light harvesting capacity and synergistically electronic interaction of this synergistically interface networked organic–inorganic membrane, it possesses accelerated dynamics for separating/transferring photoexcitons and restraining photoexciton recombination, thereby outstanding CTC reduction rate (1.25 × 10-2 min−1) and HTH conversion rate (7.45 mmol∙m−2∙h−1) were achieved under SSL-irradiation, and highly stable photoactivity was maintained even being recycled for dozens of times owing to the convenient separation/recovery performance and stable organic–inorganic matrix. Subsequently, a panel reactor for wastewater purification was constructed to achieve 6.5 × 10-3 min−1 of CTC reduction rate under SSL-irradiation. This study provides a prospective insight for application of photocatalysis technology based on the membrane materials.

Significant augmentation of hydrogen and benzaldehyde production through mediator-free in-situ synthesis of CuNi/CN photocatalysts for benzyl alcohol splitting

Amidst growing concerns surrounding global warming and energy scarcity, there is an urgent demand for more efficient and environmentally friendly methods of hydrogen production. In response, we introduce a novel mediator-free in-situ approach for synthesizing CuNi/CN composite photocatalysts. This method entails the synthesis of copper and nickel complexes to fabricate bimetallic Cu and Ni nanoparticles on carbon nitride (CN). These catalysts are deployed for the photocatalytic dehydrogenation of benzyl alcohol, resulting in the generation of hydrogen and benzaldehyde. The CuNi bimetal-loaded CN structure provides ample active sites and demonstrates a low hydrogen reduction overpotential, thereby enhancing both charge separation and surface hydrogen reduction processes. In comparison to pure CN, the composite photocatalyst exhibits significantly improved photocatalytic activity. Notably, the composite 2 % Cu1Ni1/CN photocatalyst achieves a record-high hydrogen production rate of about 80 μmol g-1h−1, representing an impressive increase of approximately 533 times compared to pristine CN. Moreover, the catalyst offers cost-effectiveness, ease of preparation, and reusability, ensuring stable hydrogen production efficiency over multiple cycles. This precious metal-free composite photocatalyst not only facilitates the synthesis of valuable compounds but also promotes sustainable advancements in efficient hydrogen energy generation.

Controlled dispersion of Ni catalyst on N-doped carbon support for stable and selective hydrogen production from formic acid

Formic acid is a liquid organic hydrogen carrier from which hydrogen can be released together with CO2 by catalytic decomposition. The development of supported Ni catalysts for H2 production is important. Here, the effects of Ni state/dispersion are considered. For this purpose, three samples were prepared with about 3 wt% Ni deposited on porous N-doped carbon. The first sample contained predominantly Ni nanoparticles (∼2 nm), the second contained Ni clusters (<1 nm), and the third – single-atom Ni sites. The catalysts showed close activity in the gas-phase reaction. However, a minimum apparent activation energy of 105 kJ/mol and a maximum selectivity towards H2 production of 99% were achieved for the single-atom Ni catalyst. The nature of its single-atom sites was established to correspond to Ni-N4 and Ni-O4, which showed greater stability under the conditions of the catalytic reaction.

Recent advances in copper kesterite thin film photocathodes for hydrogen production via water splitting: A review

The increasing scarcity of fossil fuels has made it crucial to investigate alternative, clean, and renewable power sources. Hydrogen, the simplest element on the planet can act as an energy carrier and can be a promising solution for this quest of carbon-free energy alternates. The practical implementation of cost-effective, efficient, and stable production of hydrogen fuel from water presents a significant challenge. Researchers around the globe have been actively exploring photoelectrochemical (PEC) water-splitting methods for large-scale commercialization of hydrogen production through solar-driven processes. Among these methods, the use of semiconductor photoelectrodes (PEs) is considered highly efficient. In this review, of the effectiveness and stability of the PEs, we describe the recent progress of copper-based chalcogenides for hydrogen generation by water splitting using solar energy. It is anticipated that this report will provide insightful guidance to study the low-cost materials for solar to chemical fuel energy conversion.

Efficient solar-powered PEM electrolysis for sustainable hydrogen production: an integrated approach

The coupling of photovoltaics (PVs) and PEM water electrolyzers (PEMWE) is a promising method for generating hydrogen from a renewable energy source. While direct coupling is feasible, the variability of solar radiation presents challenges in efficient sizing. This study proposes an innovative energy management strategy that ensures a stable hydrogen production rate, even with fluctuating solar irradiation. By integrating battery-assisted hydrogen production, this approach allows for decentralized, grid-independent renewable energy systems, mitigating instability from PV intermittency. The system utilizes electrochemical storage to absorb excess energy during periods of low or very high irradiation, which falls outside the electrolyzer’s optimal power input range. This stored energy then supports the PV system, ensuring the electrolyzer operates near its nominal capacity and optimizing its lifetime. The system achieves an efficiency of 7.78 to 8.81% at low current density region and 6.6% at high current density in converting solar energy into hydrogen.

Solution Processing Silicon Heterojunction Photocathode for Efficient and Stable Hydrogen Production.

Efficient and stable photocathodes are crucial for the development of photoelectrochemical (PEC) water-splitting devices. Silicon heterojunction (SHJ) solar cell is one of the most advanced photovoltaic cells. However, due to the instability of its outermost indium tin oxide (ITO) layers in the electrolyte, a protective layer needs to be introduced on its surface. Previously reported high-quality protective layers almost all involved the use of expensive thin film manufacturing techniques such as atomic layer deposition (ALD). In this work, for the first time, a new strategy is proposed of modifying SHJ-based photocathode with yttrium hydroxide (Y(OH)3) through two-step solution methods to simultaneously improve the stability and activity. The optimized SHJ photocathode exhibits a high applied bias photon-to-current efficiency (ABPE) of 8.4% under simulated 100mWcm-2 (1 Sun) with an AM 1.5G filter in 0.5m KOH. Furthermore, the obtained SHJ photocathode demonstrates excellent stability of at least 110h at 0.3V versus RHE. In this work, combining facile direct current magnetron sputtering with a solution treatment technique provides a novel design strategy, which lowers the threshold for preparing high-quality protective layer, and paves the way for developing economic, efficient, and stable SHJ-based PEC devices.