Electrocatalytic Hydrogen Production Research Articles

Activating Interfacial Electron Redistribution in Lattice-Matched Biphasic Ni3N-Co3N for Energy-Efficient Electrocatalytic Hydrogen Production via Coupled Hydrazine Degradation.

The development of high-purity and high-energy-density green hydrogen through water electrolysis holds immense promise, but issues such as electrocatalyst costs and power consumption have hampered its practical application. In this study, we present a promising solution to these challenges through the use of a high-performance bifunctional electrocatalyst for energy-efficient hydrogen production via coupled hydrazine degradation. The biphasic metal nitrides with highly lattice-matched structures are deliberately constructed, forming an enhanced local electric field between the electron-rich Ni3N and electron-deficient Co3N. Additionally, Mn is introduced as an electric field engine to further activate electron redistribution. Our Mn@Ni3N-Co3N/NF bifunctional electrocatalyst achieves industrial-grade current densities of 500 mA cm-2 at 0.49 V without degradation, saving at least 53.3 % energy consumption compared to conventional alkaline water electrolysis. This work will stimulate the further development of metal nitride electrocatalysts and also provide new perspectives on low-cost hydrogen production and environmental protection.

Effect of molybdenum doping Zn-Co spinel oxide microspheres for efficient electrocatalytic hydrogen production in alkaline media and study supported by DFT

The rational design of efficient transition metal-based electrocatalysts for the hydrogen evolution reaction (HER) is critical for the water-splitting process. Industrial water-alkali electrolysis requires large current densities at low overpotentials, which are always limited by the intrinsic activity. Here, ZnCo2−xMoxO4 (x ≤ 0.10) spinel oxide microsphere electrocatalysts were synthesized for the process in alkaline media. Mo doping in the ZnCo2O4 crystal structure enhanced the active sites, which were responsible for the enhancement in the HER process. The ZnCo2−xMoxO4 (x = 0.06) electrocatalyst exhibited exceptional HER activity, as evidenced by an overpotential of 195 mV, Tafel slope of 81.4 mVs−1 and high stability for 40 h with 1000 cycles linear sweep voltammetry. The surface and electrochemical characterization revealed that 6% Mo-doping exhibits improved the HER activity due to a significantly higher electrochemical surface area and accelerated charge transfer kinetics at the semiconductor electrolyte interface. Density functional theory (DFT) for exploring and explaining the effect of the Mo dopants on the HER activity elucidated that hydrogen and water molecules are adsorbed on the surface of the Mo-doped ZnCo2O4 slab structures. The results show that Mo dopants enhance the chemical activity, due to water adsorption, and HER activity for enhanced electrocatalytic processes. This work provides a new insight into low-metal-cost materials for efficient and durable HER electrocatalysts and successfully showcases the catalyst model for a detailed mechanistic insight into the HER process.

Enhancing the stability of NiFe-layered double hydroxide nanosheet array for alkaline seawater oxidation by Ce doping

Electrocatalytic hydrogen production from seawater holds enormous promise for clean energy generation. Nevertheless, the direct electrolysis of seawater encounters significant challenges due to poor anodic stability caused by detrimental chlorine chemistry. Herein, we present our recent discovery that the incorporation of Ce into NiFe layered double hydroxide nanosheet array on Ni foam (Ce-NiFe LDH/NF) emerges as a robust electrocatalyst for seawater oxidation. During the seawater oxidation process, CeO2 is generated, effectively repelling Cl− and inhibiting the formation of ClO−, resulting in a notable enhancement in the oxidation activity and stability of alkaline seawater. The prepared Ce-NiFe LDH/NF requires only overpotential of 390 mV to achieve the current density of 1 A cm−2, while maintaining long-term stability for 500 h, outperforming the performance of NiFe LDH/NF (430 mV, 150 h) by a significant margin. This study highlights the effectiveness of a Ce-doping strategy in augmenting the activity and stability of materials based on NiFe LDH in seawater electrolysis for oxygen evolution.

Recent strategies for improving the catalytic activity of ultrathin transition metal sulfide nanosheets toward the oxygen evolution reaction

Hydrogen is considered as one of the clean secondary energy sources required in industry and daily life. Electrocatalytic hydrogen production is believed to be the most reliable method for converting renewable energy into chemical energy. Two-dimensional (2D) transition metal disulfides (TMDs), as an emerging electrocatalysts, have been widely investigated for oxygen evolution reaction (OER) in water splitting. Herein, this review summarizes the recent progress and the strategies of ultrathin TMDs for improving the OER electrocatalytic activities. The basic catalytic mechanism of OER is first introduced, and then the catalytic characteristics of 2D TMDs are presented. Importantly, this review specifically concentrates on strategies to improve catalytic activity such as phase engineering, defect/vacancy engineering, heterostructure, doping effect, and catalyst support material. It can be concluded that these regulatory strategies can largely enhance the electrocatalytic performance by increasing the active site exposure and improving the electrocatalytic kinetics. In addition, the challenges and perspectives of 2D TMDs catalysts are presented, which offers valuable guidance in designing efficient and low-cost OER electrocatalysts for future energy applications. We hope that this review will inspire future studies and bridge the gap between strategy design and practical application.

Dual-strategy engineered nickel phosphide for achieving efficient hydrazine-assisted hydrogen production in seawater.

Electrocatalytic hydrogen production in seawater to alleviate freshwater shortage pressures is promising, but is hindered by the sluggish oxygen evolution reaction and detrimental chloride electrochemistry. Herein, a dual strategy approach of Fe-doping and CeO2-decoration in nickel phosphide (Fe-Ni2P/CeO2) is rationally designed to achieve superior bifunctional catalytic performance for the hydrogen evolution reaction (HER) and hydrazine oxidation reaction (HzOR) in seawater. Notably, the two-electrode Fe-Ni2P/CeO2-based hybrid seawater electrolyzer realizes energy-efficient and chlorine-free hydrogen production with ultralow cell voltages of 0.051 and 0.597 V at 10 and 400 mA cm-2, which are significantly lower than those needed in the hydrazine-free seawater electrolyzer. Density functional theory calculations manifest that the combination of Fe doping and heterointerface construction between Fe-Ni2P and CeO2 can adjust the electronic structure of the Ni2P and optimize the water dissociation barrier and hydrogen adsorption free energy, leading to improvement of the intrinsic catalytic performance. This route affords a feasible solution for future large-scale hydrogen generation using abundant ocean water.

Recent progress in energy-saving electrocatalytic hydrogen production via regulating the anodic oxidation reaction.

Hydrogen energy with its advantages of high calorific value, renewable nature, and zero carbon emissions is considered an ideal candidate for clean energy in the future. The electrochemical decomposition of water, powered by renewable and clean energy sources, presents a sustainable and environmentally friendly approach to hydrogen production. However, the traditional electrochemical overall water-splitting reaction (OWSR) is limited by the anodic oxygen evolution reaction (OER) with sluggish kinetics. Although important advances have been made in efficient OER catalysts, the theoretical thermodynamic difficulty predetermines the inevitable large potential (1.23 V vs. RHE for the OER) and high energy consumption for the conventional water electrolysis to obtain H2. Besides, the generation of reactive oxygen species at high oxidation potentials can lead to equipment degradation and increase maintenance costs. Therefore, to address these challenges, thermodynamically favorable anodic oxidation reactions with lower oxidation potentials than the OER are used to couple with the cathodic hydrogen evolution reaction (HER) to construct new coupling hydrogen production systems. Meanwhile, a series of robust catalysts applied in these new coupled systems are exploited to improve the energy conversion efficiency of hydrogen production. Besides, the electrochemical neutralization energy (ENE) of the asymmetric electrolytes with a pH gradient can further promote the decrease in application voltage and energy consumption for hydrogen production. In this review, we aim to provide an overview of the advancements in electrochemical hydrogen production strategies with low energy consumption, including (1) the traditional electrochemical overall water splitting reaction (OWSR, HER-OER); (2) the small molecule sacrificial agent oxidation reaction (SAOR) and (3) the electrochemical oxidation synthesis reaction (EOSR) coupling with the HER (HER-SAOR, HER-EOSR), respectively; (4) regulating the pH gradient of the cathodic and anodic electrolytes. The operating principle, advantages, and the latest progress of these hydrogen production systems are analyzed in detail. In particular, the recent progress in the catalytic materials applied to these coupled systems and the corresponding catalytic mechanism are further discussed. Furthermore, we also provide a perspective on the potential challenges and future directions to foster advancements in electrocatalytic green sustainable hydrogen production.

Electrochemical hydrogen generation by a four-coordinate square-planar Ni(ii) complex with an N2P2-type ligand

Electrochemical and DFT studies on electrocatalytic hydrogen production in Ni(ii) complexes of N2P2-type ligands with/without amino group showed that the amino group plays a role in increasing basicity of pyridyl N atom as well as proton capturing.

Lexical and Syntactic Features of English for Electrocatalytic Hydrogen Production and Strategies for E-C Translation

Lexical and Syntactic Features of English for Electrocatalytic Hydrogen Production and Strategies for E-C Translation

Engineering ultrafine PtIr alloy nanoparticles into porous nanobowls via a reactive template-engaged assembly strategy for high-performance electrocatalytic hydrogen production

We demonstrate self-sacrificial templated strategy for the synthesis of hollow and porous PtIr alloyed nanobowls composed of ultrafine nanoparticles and the resulting self-supported Pt7Ir NBs exhibit superior HER performance.

A hierarchical carbon foam-hosted Co2P nanoparticles monolithic electrode for ampere-level and super-durable electrocatalytic hydrogen production.

In this work, we develop a hierarchical carbon foam-based monolithic electrode (Co2P@HCF) from Co2+-adsorbed polyvinyl alcohol (PVA) sponge via the successive carbonization and phosphorization. Owing to the 3D hierarchical porous structure, excellent electrolyte wettability, good mechanical strength, and intimate embedding of highly dispersed Co2P nanoparticles, the Co2P@HCF electrode delivers a high current density of 1.0 A cm-2 for the hydrogen evolution reaction (HER) at ultralow overpotentials of 189.6 and 218.6 mV in 0.5 M H2SO4 and 1.0 M KOH solutions, respectively, with remarkable durability for 100 h.

Vacancy induced microstrain in high-entropy alloy film for sustainable hydrogen production under universal pH conditions

A novel vacancy-induced microstrain engineering strategy is developed in FeCoNiCrPt high-entropy alloy, enabling high activity and long lifetime hydrogen evolution under universal pH conditions.

Rational design of adenine appended synthetic cobalt catalysts via click reaction for electrocatalytic hydrogen production

Green hydrogen has emerged as a critical component in the upcoming renewable energy landscape. Enzyme architecture remains the prime inspiration for designing environment-friendly, efficient, and economical H2 production catalysts from water. The strategic incorporation of peripheral protic functionalities around synthetic metal cores specifically impacts the electrocatalytic H2 evolution reactivity. Here, we have deployed a click chemistry methodology to incorporate a 1,2,3-triazole linker in either meta vs. para position to connect a cobaloxime core with nucleobase adenine. The variation in specific positioning (meta vs. para) of the linker creates two isomeric ligands and their corresponding cobaloxime derivatives. The trifunctional ligand motif positively influences the reactivity of the cobaloximes, as the para-substituted complex produces H2 at a rate of 5350 s−1 with an overpotential <350 mV in near-neutral aqueous conditions. The meta-substituted complex displayed relatively slower catalysis (rate 3700 s−1), albeit with similar energy efficiency under analogous conditions. These robust catalysts also demonstrated substantial H2 production from water under photocatalytic conditions with an appreciable turnover number (TON) of 150 and 100 for the para- and meta-substituted complexes, respectively. The complementary electrochemical and spectroscopic techniques indicate the designed ligand's dual effect (electronic and peripheral) on the catalytic reactivity, where the para-substituted pyridinyl ligand displayed better reactivity than the meta-derivative.

Bifunctional S-scheme CdSSe/Bi2WO6 heterojunction catalysts exhibit generalized boosting performance in photocatalytic degradation of tetracycline hydrochloride, photoelectrochemical and electrocatalytic hydrogen production

In this work, by a simple method of hydrothermal synthesis, the CdSSe/Bi2WO6 S-scheme heterojunction catalyst is successfully obtained and the results are verified by XPS, EPR, band structure, etc. The S-scheme heterojunction can maintain the strong redox potential energy position of both catalysts, and adjust the electron transfer path to improve the electron-hole separation efficiency, and thus improve the charge transfer efficiency. CdSSe has a high conduction band (−1.13 eV) and a narrow bandgap width (1.59 eV), exhibiting good light absorption characteristics and reduction ability; the valence band position of Bi2WO6 is much low (2.58 eV), indicating good oxidation activity. This heterojunction has excellent oxidation and reduction capabilities and exhibits multifunctional catalysts. Its photocatalytic degradation ability of tetracycline hydrochloride is 2.2 times that of the original CdSSe, while its photoelectrochemical activity is 11 times that of CdSSe, reaching a photocurrent density of − 2.081 mA/cm2 at 0 V (vs. RHE). The electrocatalytic activity of its hydrogen evolution has also been enhanced. This study developed a design strategy for a novel bifunctional S-scheme heterojunction catalyst.

Electrocatalytic Hydrogen Production and Synergistic Formaldehyde Degradation

Electrocatalytic Hydrogen Production and Synergistic Formaldehyde Degradation

Interfacial Electron Potential Well Facilitates the Design of Cobalt Phosphide Heterojunctions for Hydrogen Evolution.

The interfacial electron modulation of electrocatalysts is an effective way to realize efficient hydrogen production, which is of great importance for future renewable energy systems. However, systematic theory-guided design of catalysts in heterojunction coupling is lacking. In this work, a multi-level theoretical calculation is performed to screen optimal candidates to form a heterojunction with CoP (101) surface for electrocatalytic hydrogen production. To overcome the weak adsorption of H+ on CoP (101), rational design of electrons potential well at the heterojunction interface can effectively enhance the hydrogen adsorption. All p-type cobalt-based phosphides are considered potential candidates at the beginning. After screening for conductivity, stability, interface matching screening, and ΔGH* evaluation, the CoP/Co2P-H system is identified to be able to display optimal hydrogen production performance. To verify the theoretical design, CoP, CoP/Co2P-H, and CoP/Co2P-O are synthesized and the electrochemical analysis is carried out. The hydrogen evolution reaction (HER) performance is consistent with the prediction. This work utilizes the electron potential well effect and multi-level screening calculations to design highly efficient heterojunction catalysts, which can provide useful theoretical guidance for the rational design of heterojunction-type catalysts.

Regulation engineering of lignin-derived N-doped carbon-supported FeNi alloy particles towards efficient electrocatalytic oxygen evolution

The electrocatalytic hydrogen production technology using green energy can reduce the dependence on traditional fossil fuels and the net emission of carbon dioxide. However, the high overpotential and low efficiency of the oxygen evolution reaction (OER) on the anode limit the overall water splitting. Here, carboxylic acid ligands with coordination function were designed and synthesized by modifying the surface functional groups of lignin. Bimetallic functionally-doped lignin-derived carbon materials (Fe4Ni4@NC) were synthesized by continuous ion layer adsorption and pyrolysis process using Fe and Ni transition metals as source and template. The catalyst requires only 214 mV of overpotential to produce 10 mA·cm−2, which has much faster catalytic kinetics. Theoretical calculation shows that the energy barrier of rate-determining step in OER is reduced by appropriate feed ratio and nano-size. The facile strategy opens up an economical and efficient solution for designing OER electrocatalysts with high catalytic activity and excellent stability.

Design of hierarchical integration superbranched Ni–S clusters for efficient, stable hydrogen production

Transition metal sulfides (TMSs), especially iron-based metals (Fe, Co, Ni), were considered the most potential catalysts to replace noble metal-based materials for hydrogen evolution reaction (HER). This work selected metal ions as a variable to modulate the catalytic activity. Designing an electrode consisting of iron-based metal atoms sulfides sweeper-like hyperbranched clusters grown on nickel foam (NF) for HER. This particular structure consisted of 1D nanorods and adequate exposure of the lattice dislocation to exhibit enhanced electrocatalytic activity with low overpotential (135.9 mV) in alkaline conditions at 10 mA cm−2. In addition, stability test results showed that the electrode exhibited good durability. The enhanced electrocatalytic activity of Ni–S could be owing to high electrical conductivity characteristic, the hierarchical structure constituted with NF and the large active surface area of the self-grown electrode further facilitating the production of H2. The Ni sites on the Ni3S2 (110) crystal faces facilitated H adsorption, and all radical reactions under applied voltage proceed spontaneously. This work guides the selection and development of substrates for the design of synthetic transition metal catalysts, leading to cost-effective and efficient electrocatalytic hydrogen production.

Collaborative coupling catalytic interface enabling efficient hydrogen evolution in universal-pH electrolytes and seawater

Developing particularly effective and synergistic non-noble metal electrocatalysts for complex chemical processes remains an enormous challenge. Herein, the collaborative catalytic interface among rare earth compounds, bimetallic carbide, and N-doped carbon is demonstrated to accelerate the hydrogen evolution process in acid-base electrolytes and seawater. Therefore, the HER performance of the resultant electrocatalyst in both 1.0 M KOH and 0.5 M H2SO4 with the overpotentials of 70 and 79 mV, to achieve the current density of 10 mA cm−2. In addition, they also show excellent performance of HER in natural seawater and have good characteristics in catalytic activity and stability, which is reflected in the slight decrease of activity after the 5000 cyclic voltammetry (CV) cycle and almost no attenuation after electrolysis for 10 h. This work will pave a new way for collaborative coupling interface catalysis strategy to boost electrocatalytic hydrogen production in acidic, alkaline, and seawater.

Defect-rich hollow double-shell bimetallic phosphides for electrocatalytic hydrogen evolution over a wide pH range

Developing non-precious metal catalysts with high catalytic efficiency remains a challenge in the electrocatalytic hydrogen production field. Herein, a defect-rich double-shell CNHC-O-P microsphere is constructed by urea etching and then a step-by-step phosphating process via Co3Ni7-MOFs as the precursor. During the urea etching process, the organic ligands in MOFs are substituted by CO32– and OH– anions to form basic carbonate double-shell microsphere. Then, the released CO2 and H2O molecule during the calcination process produce a porous and defective oxide double-shell microsphere. Furthermore, more lattice distortions and defects are formed through O and P exchanging during the gas phosphating process. The unique defect-rich and double-shell structure provides a rich and accessible active site for enhanced HER performance. The optimized CNHC-O-P shows the overpotentials of 197 mV, 253 mV, and 245 mV at 10 mA·cm−2 current density in 1 M KOH, 0.5 M H2SO4, and 1 M PBS solution, separately. This work provides a new method for designing and synthesizing defect-rich and double-shell nanomaterials for energy storage and conversion application.

Defects go green: using defects in nanomaterials for renewable energy and environmental sustainability

Induction of point defects in nanomaterials can bestow upon them entirely new physics or augment their pre-existing physical properties, thereby expanding their potential use in green energy technology. Predicting structure-property relationships for defects a priori is challenging, and developing methods for precise control of defect type, density, or structural distribution during synthesis is an even more formidable task. Hence, tuning the defect structure to tailor nanomaterials for enhanced device performance remains an underutilized tool in materials design. We review here the state of nanomaterial design through the lens of computational prediction of defect properties for green energy technology, and synthesis methods to control defect formation for optimal performance. We illustrate the efficacy of defect-focused approaches for refining nanomaterial physics by describing several specific applications where these techniques hold potential. Most notably, we focus on quantum dots for reabsorption-free solar windows and net-zero emission buildings, oxide cathodes for high energy density lithium-ion batteries and electric vehicles, and transition metal dichalcogenides for electrocatalytic green hydrogen production and carbon-free fuels.