Sustainable Hydrogen Production Research Articles

Exploring Low Temperature Proton Exchange Membrane Water Electrolysis Anode Catalyst Degradation Under Cathode Backpressure Conditions

Hydrogen is expected to play an important role in the decarbonization of the future energy landscape by integrating renewable, nuclear, and fossil fuels and using excess power from the grid to produce H2 that can then be stored and used for a variety of applications ranging from ammonia and steel production, stationary power, buildings, and transportation.1 In order to achieve low-cost hydrogen production that is competitive with steam methane reformation (SMR), it is necessary to decrease the capital cost and this can be done by leveraging variable renewable energy (VRE) as an electricity feedstock for LTE.2 However, cost, and durability are still current challenges in state-of-the art water electrolysis systems. More research is needed to better understand the effects of dynamic operation on electrolyzer degradation. Understanding the degradation mechanisms governing intermittent electrolysis operation can enable future improvements related to component design and system operation.In recent years, electrolyzer anode degradation has been investigated during continual intermittent operation at the single cell level. Square-wave potential cycling demonstrated higher anode degradation compared to the triangle-wave cycling over the same 525 hour test (21.9 d).3 Electrolyzers operating at differential pressures and producing electrochemically compressed hydrogen could decrease the hydrogen production cost by eliminating the need for equipment related to mechanical compression.4 This work investigates the dynamics of low-temperature proton exchange membrane (PEM) electrolyzers, with a specific focus on anode catalyst layer degradation from redox transition when subjected to hydrogen crossover from cathode backpressure conditions. While cathode backpressure and operation requirements are well understood from an industry perspective, its impact on degradation mechanisms and loss rates has been relatively underexplored when low-temperature electrolysis is focused on cost reduction and variable load.In this study, hydrogen cross-over rates were varied by cathode backpressure conditions (ambient to 30 Bar) and were compared to elucidate the impact hydrogen has on anode catalyst layer degradation. The durability test duration varied from 168 – 500+ hrs. Hydrogen cross-over rates were found to correlate to cell potential during operational shutdowns and loss rates during load cycling. Electrochemical impedance spectroscopy further demonstrates higher degrees of kinetic loss and the immergence of additional loss mechanisms. The findings presented in this research contribute to the fundamental understanding of low-temperature PEM electrolysis dynamics under cathode backpressure conditions. The implications of this research offer practical insights for the design and operation of efficient and durable electrolysis systems crucial for the advancement of sustainable hydrogen production technologies.(1) H2@Scale. Hydrogen and Fuel Cell Technologies Office. https://www.energy.gov/eere/fuelcells/h2scale.(2) Mark, R.; Jadun, P.; Gilroy, N.; Connelly, E.; Boardman, R.; Simon, A. J.; Elgowainy, A.; Zuboy, J. The Technical and Economic Potential of the H2@Scale Concept within the United States; NREL/TP-6A20-77610; National Renewable Energy Laboratory: Golden, CO, 2020.(3) Alia, S. M.; Reeves, K. S.; Yu, H.; Park, J.; Kariuki, N.; Kropf, A. J.; Myers, D. J.; Cullen, D. A. Electrolyzer Performance Loss from Accelerated Stress Tests and Corresponding Changes to Catalyst Layers and Interfaces. Journal of The Electrochemical Society 2022, 169 (5), 054517. https://doi.org/10.1149/1945-7111/ac697e.(4) Ragnhild Hancke, Thomas Holm, and Øystein Ulleberg, “The Case for High-Pressure PEM Water Electrolysis,” Energy Conversion and Management 261 (2022): 115642, https://doi.org/10.1016/j.enconman.2022.115642. Figure 1

Rapid Synthesis of Ruthenium-Copper Nanocomposites as High-Performance Bifunctional Electrocatalysts for Electrochemical Water Splitting.

Development of high-performance, low-cost catalysts for electrochemical water splitting is key to sustainable hydrogen production. Herein, ultrafast synthesis of carbon-supported ruthenium-copper (RuCu/C) nanocomposites is reported by magnetic induction heating, where the rapid Joule's heating of RuCl3 and CuCl2 at 200A for 10s produces Ru-Cl residues-decorated Ru nanocrystals dispersed on a CuClx scaffold, featuring effective Ru to Cu charge transfer. Among the series, the RuCu/C-3 sample exhibits the best activity in 1m KOH toward both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), with an overpotential of only -23 and +270mV to reach 10mAcm-2, respectively. When RuCu/C-3 is used as bifunctional catalysts for electrochemical water splitting, a low cell voltage of 1.53V is needed to produce 10mAcm-2, markedly better than that with a mixture of commercial Pt/C+RuO2 (1.59V). In situ X-ray absorption spectroscopy measurements show that the bifunctional activity is due to reduction of the Ru-Cl residues at low electrode potentials that enriches metallic Ru and oxidation at high electrode potentials that facilitates the formation of amorphous RuOx. These findings highlight the unique potential of MIH in the ultrafast synthesis of high-performance catalysts for electrochemical water splitting.

Resonance-driven microwave heating for improved methane conversion to hydrogen

Efficient hydrogen production through methane pyrolysis is hindered by high temperature required and frequent catalyst deactivation due to carbon deposition. This study proposes a novel use of variable-frequency microwave heating to enhance the efficiency and stability of methane pyrolysis by leveraging the resonance effects between microwave frequencies and dielectric properties of activated charcoal (AC). A solid-state variable-frequency microwave reactor was employed to modulate microwave frequencies to match the dielectric properties of AC, with a peak tanδ of 0.19 at 4600 MHz. Experimental results showed that at a resonance frequency of 4650 MHz and a microwave power of 100 W, the reaction temperature of AC reached 960 °C within 2 min, achieving a 100% methane conversion rate. However, carbon deposition reduced the conversion rate to 35.1% after 150 min. By cyclically adjusting the microwave frequencies between 4650 MHz and 4640 MHz, the catalyst was successfully reactivated, restoring the conversion rate to 100%. This frequency modulation method enabled continuous methane pyrolysis for 1300 min, highlighting the potential of variable-frequency microwave heating as a novel and efficient approach for a sustainable production of green hydrogen.

Study on the Catalytic Activity and Selectivity of Manganese Dioxide-Modified Nickel–Iron-Based Hydroxide Electrodes for Initiating the Oxygen Evolution Reaction in Natural Seawater

Transition metal oxides, particularly NiFe(OH)2, are recognized for their high oxygen evolution reaction (OER) activity and structural stability. However, their performance in natural seawater electrolysis remains insufficiently studied. Manganese dioxide (MnO2), which is known for its multiple crystal phases and high OER selectivity, can be incorporated to enhance the catalytic properties. In this study, the OER catalytic performance of carbon cloth-supported manganese dioxide-modified nickel–iron bimetallic hydroxide (MnO2-NiFe-LDH/CC) electrodes was explored in both alkaline and natural seawater. Electrochemical tests demonstrated that the MnO2-NiFe-LDH/CC electrode achieved overpotentials of 284 mV and 363 mV at current densities of 10 mA·cm−2 and 100 mA·cm−2, respectively, with a Tafel slope of 68.6 mV·dec−1 in alkaline seawater. Most importantly, the prepared MnO2-NiFe-LDH/CC electrode maintained stable OER performance over 120 h of testing. In natural seawater, the MnO2-NiFe-LDH/CC electrode outperformed the NiFe-LDH/CC electrode by exhibiting an oxygen evolution selectivity of 61.1%. This study highlights the potential of MnO2-modified nickel–iron-based materials for efficient and stable OER in seawater electrolysis, which offers a promising approach for sustainable hydrogen production in coastal desert regions.

Optimizing wind-solar hydrogen production through collaborative strategy with ALK/PEM multi-electrolyzer arrays

This paper presents an innovative sustainable hydrogen production system integrating solar and wind energy to provide power to alkaline (ALK) and proton exchange membrane (PEM) electrolyzers. On this basis, a novel source and load collaborative optimization strategy is proposed to optimize the hydrogen production system, aiming to address the challenges of the intermittent and variable nature of renewable energy sources. The proposed strategy consists of a classification prediction module using the XGBoost algorithm, which analyzes historical energy generation data to predict optimal electrolyzer operation. Furthermore, the proposed collaborative optimization strategy is able to balance the loads between the electrolyzer arrays, aiming to minimize cold-start situations, prolong steady-state hydrogen production time, and reduce operational variations due to maintenance. The proposed strategy is proved to significantly reduce the standard deviation of the electrolyzer runtime, enhancing the overall system stability, and contributing to the reduction of maintenance frequency. Theoretical analyzes and extensive simulation results validate the effectiveness of the proposed strategy in improving hydrogen production efficiency and sustainability. This work contributes to the integration of renewable energy sources for clean energy production, and provides a practical and effective solution for the urgently needed green hydrogen production.

Harnessing Ti3C2-WS2 Nanostructures as Efficient Energy Scaffoldings for Photocatalytic Hydrogen Generation

Two-dimensional (2D) Ti3C2 MXene have attracted a lot of attention as frontier materials for the development of effective photocatalysts that can transform solar energy into chemical energy, which is essential for water splitting to produce hydrogen. Here, we use first principle calculations to understand the structural, electronic, and vibrational features of a novel heterostructure comprising a monolayer of tungsten disulfide (WS2) and titanium carbide (Ti3C2) MXene. Our theoretical calculations revealed that the Ti3C2 maximizes the interfacial contact area with the WS2 monolayer creating a strong p–-d hybridization for the WS2/Ti3C2 heterostructure. As a result, a well-constructed Schottky junction is enabled, facilitating an interconnected electron pathway across the interface which is conducive for an efficient photocatalytic performance. Further, the experimentally designed WS2/Ti3C2 heterostructure and its photocatalytic activity based on the synergistic action between MXene and WS2 is investigated. Optical properties calculated are compared with experimental data derived from UV-Visible spectroscopy. The excellent conductivity and stability along with the light absorption in the visible region of WS2/Ti3C2 enhances the photocatalytic performance approaching photocurrent densities of ∼33 and 120 μA/cm2 in the HER and OER region, respectively. Overall, the present research not only improves our understanding of WS2/Ti3C2 heterostructure for an improved photocatalytic activity, but also provides an efficient method toward sustainable hydrogen production.

Strong electron coupling effect of non-precious metal Schottky junctions enhanced square meter level photocatalytic hydrogen evolution

Photocatalytic hydrogen production technology utilizes solar energy to decompose water into hydrogen, helping to alleviate the pressure of energy depletion. Engineering of non-precious metal nanomaterials as cocatalysts can play a significant role in low-cost, sustainable, and large-scale photocatalytic hydrogen production. Herein, MnCdS-Vs/NiCo2S4 (MCSN) Schottky junction nanomaterials with strong electron coupling effect were prepared by a two-step hydrothermal method and successfully applied to a square meter hydrogen evolution device. The optimized MCSN material demonstrated high hydrogen evolution activity of 34.28mmolg-1 h-1, which is 9.34 and 685.60 times higher than that of pure MnCdS-Vs and NiCo2S4, respectively. More importantly, in a square meter (1 m2) flat-plate reactor, MCSN produced H2 evolution approximately 201mmol in 5h, showcasing its potential for large-scale applications. In-situ XPS and DFT calculations demonstrated that MnCdS-Vs interacts with NiCo2S4 to produce a strong electron coupling effect and form a Schottky junction. It promotes the facilitated the directional migration of photogenerated electrons from MnCdS-Vs to NiCo2S4, but also effectively suppressed electron backflow through the Schottky barrier. Furthermore, the abundance of sulfur vacancies enhanced visible light absorption capability, further improving photocatalytic hydrogen evolution performance. This work delves into the role of defect engineering and Schottky junction design in enhancing photocatalytic performance, providing new insights into transitioning photocatalytic hydrogen production technologies from small-scale laboratory experiments to large-scale practical applications.

S-scheme NaxCoO2/g-C3N4 heterojunction photo-electrocatalysts for water splitting

Enabling a highly efficient charge separation on hetero-structural photo-electrocatalyst is crucial to achieve a high efficiency of water splitting technology for sustainable green hydrogen production. Herein, novel S-scheme hetero-structural materials, NaxCoO2/g-C3N4 (x = 0.5, 0.6, and 0.74), have been employed as photo-electrocatalysts for water splitting reaction. Their corresponding overpotential values under irradiation condition with the current density of 10 mA cm−2 were about 590 mV (x = 0.74), 555 mV (x = 0.6) and 710 mV (x = 0.5), respectively. Compared to the dark condition, NaxCoO2/g-C3N4 exhibited lower overpotentials. XPS and in-situ KPFM results further confirmed that an interfacial electric field was formed at the interface of NaxCoO2 and g-C3N4. Under the irradiation condition, the electrons from the conduction band of NCO flow toward to the valence band of CN to form S-scheme heterostructure, which could highly accelerate the reducing capability of CN, hence splitting water to produce hydrogen gas.

Electrodeposition of Nickel–Molybdenum–Phosphide on copper foam electrode for efficient hydrogen evolution reaction

In the quest for efficient and cost-effective catalysts to drive the hydrogen evolution reaction (HER) in electrochemical water splitting, copper foam (CuF) is a favorable candidate for electrode coating. Precious metal catalysts like Pt/C dominate the field but must be improved because of their high cost and scarcity. Therefore, we have synthesized and evaluated a sequence of nickel-originated electrocatalysts (Ni, NiMo, NiP, and NiMoP) with the electrodeposition of CuF to facilitate substantial improvements in HER performance. Herein, the Ni–Mo–P ternary system, owing to its desirable electronic structure and catalytic mechanism, contributes to enhancing the thermodynamics and kinetics of the HER. Performance analysis reveals that all studied catalysts follow the order of Ni/CuF > NiMo/CuF > NiP/CuF > NiMoP/CuF regarding both the Tafel slope and overpotential. Hence, the top performer, NiMoP/CuF, exhibits tremendous thermodynamics with an η10 = 159 mV and Tafel slope kinetics of 126.66 mV·dec⁻1 at 1.0 M KOH in water splitting. Overall, this report presents a well-capable way of optimizing the electrocatalytic function and stability of CuF-electro-coated catalysts for the HER. This research opens new avenues for cost-effective, stable, and efficient HER catalysts, showcasing the potential of NiMoP/CuF in advancing sustainable hydrogen production technologies.

Architectural Decoration of Bioleached NiFeP Surfaces by Co3O4 Flowers for Efficient Electrocatalytic Hydrogen Generation.

In the quest for sustainable hydrogen production via water electrolysis, the development of high-performance, noble-metal-free catalytic systems is highly desired. Herein, we proposed an innovative strategy for the development of an electrocatalyst by refining the surface characteristics of a NiFeP alloy through microbiological techniques and subsequent enrichment of active sites by tailoring 3D hierarchical flower-like structures with intact and interconnected two-dimensional (2D) Co3O4. The resultant 3D Co3O4@NiFeP-5/24h has a porous structure comprised of intercrossed nanoparticles covering the entirety of the catalytic surface. This design ensures comprehensive electrolyte ion penetration and facilitates the release of gas bubbles while reducing bubble adhesion rates. Remarkably, the Co3O4@NiFeP-5/24h electrode demonstrates superior hydrogen evolution (HER) performance in an alkaline medium, characterized by its high stability, low overpotential (106 mV at a current density of 10 mA cm-2), and reduced Tafel slope (98 mV dec-1). Besides, the minimized interfacial contact resistance among the phases of electrode and electrolyte emphasizes the high HER performance of the 3D Co3O4@NiFeP-5/24h electrode. The innovative design and fabrication strategy employed herein holds significant potential for advancing the field of water-splitting electrocatalysis, offering a promising path toward the rational design and development of noble-metal-free electrocatalysts.

Electrochemical performance of in-situ electrodeposited spinel-structured High entropy Oxides/ NiFeCuMoMn-High entropy Alloy multiphase electrocatalysts for seawater electrolysis

Seawater electrolysis plays a pivotal role in advancing sustainable hydrogen production. High entropy alloys (HEAs), an innovative class of materials, have garnered significant attention for seawater electrolysis research in recent years due to their exceptional mechanical strength, catalytic efficiency, and corrosion resistance properties. This study presents the synthesis of a novel Ni-Fe-Cu-Mo-Mn based high entropy alloy catalyst featuring in-situ grown high entropy oxides (HEOs). This material exhibits HER overpotentials of η10 (Overpotential at 10mA)=50.5 mV in 1 M KOH solution and η10 = 371 mV in natural seawater with a pH ≈ 8.2, after 50 h of Hydrogen evolution reactio (100 mA·cm−2), the η10 in seawater decreased from 371 mV to 343 mV. Demonstrates some autocatalytic capacity. Analytical results indicated that the HEOs/NFCMM (NiFeCuMoMn) -HEA surface is characterized by a spinel structure. The presence of this spinel-structured HEOs layer on the HEOs/NFCMM-HEA catalyst's surface enhances its ability to adsorb H2O effectively and facilitates the desorption of H* from non-acidic electrolytes, thereby significantly boosting the HER process.

Alkaline hydrogen evolution reaction catalyzed by atomically dispersed ruthenium on phosphorus-nitrogen co-doped porous carbon

Exploring high-efficiency catalyst toward hydrogen evolution reaction (HER) for sustainable hydrogen production is critical for building a forthcoming hydrogen economy. Atomically dispersed catalysts have shown great promises for catalyzing HER yet further fine-tuning the coordination chemical environment to boost the performance is still challenging. Herein, we report the synthesis and electrocatalytic HER application of Ru single atoms dispersed in P, N co-doped porous carbon (Ru SAs@PNC). Spherical aberration corrected scanning transmission electron microscope (AC-STEM) analysis revealed the formation of atomically dispersed Ru single atoms. The as-prepared Ru SAs@PNC catalyst showed excellent HER activity in 1 M KOH, evidenced by a small overpotential of 21 mV @ 10 mA cm−2 and a low Tafel slope of 31 mV dec−1, both of which are comparable to the Pt/C benchmark catalyst. It also exhibited great durability for long-time operation, as demonstrated by negligible overpotential increase in the 50 h E-t test, and outperformed stability in the accelerated durability test. Such excellent HER performance is mainly attributed to the N, P co-doped chemical coordination environment that differs from most widely reported solely nitrogen-coordinated Ru single atoms.

Tuning built-in potential of NiP/NiFe LDH p-n junction towards efficient electrocatalytic water and urea oxidation

Oxygen evolution reaction (OER) and urea oxidation reaction (UOR) are critical half-reactions to realize sustainable hydrogen production. However, the sluggish dynamics derived from the multi-electron pathways necessitate the exploration for efficient catalysts. Herein, a p-n junction nanorod array composed of Mo doped NiP nanorod and ultrathin NiFe LDH nanosheets (NiMoP/NiFe LDH) is proposed to regulate charge distribution of interface for triggering decomposition of water and urea. The p-n junction with a powerful built-in potential (EBI) of 1.2 V at the interface facilitates the adsorption and fracture of chemical group in water and urea molecules. Consequently, the heterostructured electrode demonstrates exceptional electrochemical performance with ultralow potentials of 1.43 and 1.33 V (vs. RHE) at 10 mA cm−2 for OER and UOR, respectively. The overall urea electrolysis driven by NiMoP/NiFe LDH needs only 1.51 V to deliver 100 mA cm−2. This work demonstrates a promising strategy to regulate the EBI of semiconductor heterostructure for energy conversion and sewage treatment.

Reasonably construct GDY/CeO2/Mn0.2Cd0.8S double S-scheme heterojunction for improvement photocatalytic hydrogen production

Reasonably designing and optimizing the structure of photocatalysts aims to effectively enhance light absorption, accelerate charge separation and transfer, and achieve sustainable photocatalytic hydrogen production. In this study, a simple self-assembly method was used to prepare the GDY/CeO2/Mn0.2Cd0.8S ternary system. The addition of GDY and CeO2 significantly enhances the light absorption range of Mn0.2Cd0.8S, enhancing the separation and transmission of electron hole pairs and provides more active sites for hydrogen production. Moreover, an S-scheme heterojunction was constructed between the three catalysts, maximizing their oxidation–reduction ability. In addition, the built-in electric field formed between the catalysts also provides power for electron transfer, ensuring efficient and orderly reaction. This work provides ideas for the rational construction of heterojunctions, improving charge transfer, and designing high-performance catalysts to solve energy problems.

Promising porous spherical PbI2/poly-2-aminobenzenethiol nanocomposite as a photocathode for hydrogen generation from Red Sea water

A highly efficient porous spherical nanocomposite photocathode, known as PbI2/poly-2-amino benzene thiol (PbI2/P2ABT), is created through a two-step reaction process involving the oxidation of 2-amino benzene thiol with iodine, followed by a double displacement reaction. The resulting nanocomposite displays outstanding morphology, comprising spherical particles with a diameter of 500 nm and featuring nanoscale porosity with pore sizes around 5 nm. Notably, the hydrogen production estimate reaches 9.6 μmole/h·10 cm2, a promising outcome attributed to the environmentally friendly and cost-effective use of natural Red Sea water. The quantification of hydrogen gas is accomplished by assessing the photogenerated carriers using the current density relationship. The calculated Jph value experiences a substantial increase to −0.122 mA.cm−2 compared to a minimal 0.07 mA.cm−2 in the absence of light. Furthermore, the optical assessment reveals exceptional Jph values under 340 nm, reaching 0.121 mA.cm−2, which extends to the visible spectrum with a value of 0.112 mA.cm−2. The remarkable features of this nanocomposite include its cost-effectiveness, ease of fabrication, and scalability for mass production. These qualities collectively enable the conversion of Red Sea water into hydrogen gas, offering a practical and efficient solution aligned with eco-friendly and economically viable practices. This nanocomposite shows significant potential for advancing clean energy technologies and contributing to sustainable hydrogen production from natural water sources.

Structural Regulation of NiFe LDH under Spontaneous Corrosion to Enhance the Oxygen Evolution Properties.

Electrochemical water splitting holds promise for sustainable hydrogen production but restricted by the sluggish reaction kinetics at the anodic oxygen evolution. Herein, we present a room-temperature spontaneous corrosion strategy to convert inexpensive iron (Fe) on iron foam substrates into highly active and stable self-supporting nickel iron layered hydroxide (NiFe LDH) catalysts. The corrosion evolution mechanisms are elucidated combining ex-situ scanning electron microscopy (SEM) and X-ray photo electron spectroscopy (XPS) techniques, demonstrating precise control over the concentration of Ni2+ and reaction time to achieve controllable micro-structures of NiFe LDH. Taking advantage of the self-supporting morphology and hierarchical micro-/nano- structure, the NiFe LDH with optimized Ni2+ concentration and reaction time exhibits significant small overpotentials of 160 mV and 200 mV for the OER at current densities of 10 mA cm-2 and 100 mA cm-2 respectively, showcasing excellent OER activities. Furthermore, this catalyst demonstrates superior reaction kinetics, high electrochemical stability, and excellent integral water splitting performance when coupled with a commercial Pt/C cathode. The energy-efficient, cost-effective, and scalable spontaneous corrosion strategy opens new avenues for the development of high-electrochemical-interface catalysts.

Production of syngas at lower temperatures through microwave-enhanced dry reforming of methane

This study presents a novel microwave-assisted dry reforming of methane (MW-DRM) method, significantly enhancing syngas (H2+CO) production at a lower temperature of 400 °C. Compared to conventional heating dry reforming of methane (CH-DRM) processes, MW-DRM achieves higher conversion rates of CH4 (84.6%) and CO2 (85.7%) at a lower temperature of 500 °C, significantly reducing energy consumption. The CsRu/CeO2 catalyst exhibited excellent stability under microwave heating, maintaining high conversion rates and selectivity for 8 h. Detailed characterization using XRD, BET surface analysis, Raman spectroscopy, TEM, and CO chemisorption revealed insights into the structural changes of the catalyst, highlighting the selective impact of microwave heating on the catalyst structure. This study provides a promising approach for sustainable and cost-effective syngas and hydrogen production, aligning with greenhouse gas reduction goals.

Regulation of morphology and charge transfer mechanism: Oxygen vacancy-rich Mn0.2Cd0.8S/CoMoO4 S-type heterojunction promoting photocatalytic hydrogen production through hydrothermal in-situ synthesis

The development of efficient photocatalysts is a very interesting topic for sustainable hydrogen production using solar energy. In this paper, Mn0.2Cd0.8S was loaded on CoMoO4 nanorods by in-situ solvothermal method. Through morphological control, two rod-shaped elemental materials were loaded in situ to construct a composite with a ball shaped bouquet structure. The Mn0.2Cd0.8S/CoMoO4 photocatalyst with enriched oxygen vacancies was synthesized by high-temperature annealing. It is worth noting that by constructing an heterojunction, the Mn0.2Cd0.8S/CoMoO4 photocatalyst exhibits high catalytic activity and stability. The optimal H2 production rate of Mn0.2Cd0.8S/CoMoO4 was 7.04 mmol·g−1·h−1. Surprisingly, the hydrogen production rate of the composite was 35.88 times that of CoMoO4. Density functional theory (DFT) calculations showed that Mn0.2Cd0.8S/CoMoO4 has electron attraction ability and strong conductivity. X-ray photoelectron spectroscopy (XPS) confirmed the charge transfer path of the heterojunction between Mn0.2Cd0.8S and CoMoO4, which greatly promoted the spatial charge separation. This work provides a reference for combining heterojunction design with defect engineering to achieve efficient conversion of solar energy to chemical energy.

Spatially engineered local electric field for enhanced water electrolysis

Alkaline water electrolysis (AWE) stands as a well-established and promising route for sustainable hydrogen production. However, traditional AWE cells suffer from low performance and bulky size. Here, we introduce the integrated design, a streamlined architecture that maximizes space utilization and enhances inter-component contact. This geometric innovation requires only minor modifications in the manufacturing process to effectively double the gas production capacity without increasing the volume of the device across a wide voltage range. Utilizing Ni foam electrodes, the device achieves a 205 mA cm−3 output at 2.0 V. Through visual inspections and simulations, we compared the new and traditional designs, attributing performance improvements to optimized local electric fields. These findings not only demonstrate the feasibility of spatial engineering, but also illuminate a promising path to advance alkaline water electrolyzer technology.

Energy-saving hydrogen production by seawater electrolysis coupling tip-enhanced electric field promoted electrocatalytic sulfion oxidation

Hydrogen production by seawater electrolysis is significantly hindered by high energy costs and undesirable detrimental chlorine chemistry in seawater. In this work, energy-saving hydrogen production is reported by chlorine-free seawater splitting coupling tip-enhanced electric field promoted electrocatalytic sulfion oxidation reaction. We present a bifunctional needle-like Co3S4 catalyst grown on nickel foam with a unique tip structure that enhances the kinetic rate by improving the current density in the tip region. The assembled hybrid seawater electrolyzer combines thermodynamically favorable sulfion oxidation and cathodic seawater reduction can enable sustainable hydrogen production at a current density of 100 mA cm−2 for up to 504 h. The hybrid seawater electrolyzer has the potential for scale-up industrial implementation of hydrogen production by seawater electrolysis, which is promising to achieve high economic efficiency and environmental remediation.