Electrocatalysts For Hydrogen Production Research Articles

Employing shielding effect of intercalated cinnamate anion in NiFe LDH for stable and efficient seawater oxidation

Seawater electrolysis is a valuable and promising method for clean hydrogen generation. The corrosion induced from active anions in seawater and the competition between oxygen evolution reaction (OER) and chloride evolution reaction (CER) limit the overall efficiency of seawater electrolysis. Herein, shielding strategy was introduced with cinnamate anion (CNA) intercalated in NiFe LDHs (NiFe LDHCNAs) for efficient alkaline seawater oxidation. It displays an outstanding OER performance with 247 mV and 258 mV to achieve the current density of 50 mA/cm2 in 1 M KOH electrolyte and alkaline seawater (1 M KOH + real seawater), respectively. Meanwhile, CNA-NiFe LDH presents excellent durability (over 72 h at 100 mA/cm2) in 1 M KOH electrolyte and alkaline seawater. The enhanced catalytic performance and durability can ascribe to the enlarged interlayer spacing by CNA intercalation and shielding effect of CNA against chlorine corrosion. This research offers a novel approach to the design of efficient electrocatalysts for hydrogen production from seawater electrolysis.

Efficient and durable seawater electrolysis with a V2O3-protected catalyst.

The ocean, a vast hydrogen reservoir, holds potential for sustainable energy and water development. Developing high-performance electrocatalysts for hydrogen production under harsh seawater conditions is challenging. Here, we propose incorporating a protective V2O3 layer to modulate the microcatalytic environment and create in situ dual-active sites consisting of low-loaded Pt and Ni3N. This catalyst demonstrates an ultralow overpotential of 80 mV at 500 mA cm-2, a mass activity 30.86 times higher than Pt-C and maintains at least 500 hours in seawater. Moreover, the assembled anion exchange membrane water electrolyzers (AEMWE) demonstrate superior activity and durability even under demanding industrial conditions. In situ localized pH analysis elucidates the microcatalytic environmental regulation mechanism of the V2O3 layer. Its role as a Lewis acid layer enables the sequestration of excess OH- ions, mitigate Cl- corrosion, and alkaline earth salt precipitation. Our catalyst protection strategy by using V2O3 presents a promising and cost-effective approach for large-scale sustainable green hydrogen production.

Cobalt-Based Nanoscale Material: An Emerging Electrocatalyst for Hydrogen Production.

Modern civilization has been highly suffering from energy crisis and environmental pollutions. These two burning issues are directly and indirectly created from fossil fuel consumption and uncontrolled industrialization. The above critical issue can be solved through the proper utilization of green energy sources where no greenhouse gases will be generated upon burning of such materials. Hydrogen is the most eligible candidate for this purpose. Among various methods of hydrogen generation, electrocatalytic process is one of the most efficient methods because of easy handling and high efficiency. In these aspects Co-based nanomaterials are considered to be extremely significant as they can be utilized as efficient, recyclable and ideal catalytic system. In this article a series of Co-based nano-electrocatalysts has been discussed with proper structure-property relationship and their medium dependency. Therefore, such type of stimulating summary on recently reported electrocatalysts and their activity may be helpful for scientists of the corresponding field as well as for broader research communities. This can be inspiration for materials researchers to fabricate active catalysts for the production of hydrogen gas in room temperature.

Bimetallic Nitride Ni3Mo3N Microrods with Abundant Catalytic Sites Used as Efficient Electrocatalysts for Hydrogen Evolution Reaction

The importance of efficient and stable hydrogen evolution reaction (HER) electrocatalysts for hydrogen production in alkaline conditions to energy crisis resolution and environmental pollution is immense. In general, the quantity of catalytic sites in the electrocatalyst limits the current density of HER. In response to such problems, the bimetallic effect of non-noble bimetallic nitrides has been shown to regulate the corresponding catalytic sites. Here, a microrod-like non-noble bimetallic nitride catalyst with Ni3Mo3N microrods uniformly modified on nickel foam was synthesized by hydrothermal and nitriding processes. The catalyst showed high catalytic activity for HER in 1 M KOH solution. The overpotential was only 28 mV at a current density of 10 mA·cm−2, demonstrating exceptional electrochemical performance. Furthermore, it exhibited remarkable long-term stability under the same current density. This work will open up a low-cost and simple way for the synthesis of bimetallic nitrides as functional electrode materials for HER and electrochemical detection.

Review—Recent Advancements in Molybdenum Carbides for Efficient Hydrogen Evolution Reaction

Abstract The quest for economical and sustainable electrocatalysts to facilitate the hydrogen evolution reaction (HER) is paramount in addressing the pressing challenges associated with carbon dioxide emissions. Molybdenum carbide-based nanomaterials have emerged as highly promising electrocatalysts for HER due to their Pt-like catalytic proficiency, exceptional stability, and the versatility of their crystal phases. Within this comprehensive review, we explore the diverse methodologies for synthesizing molybdenum carbides, including solid-gas, solid-solid, and solid-liquid phase reactions. In addition, a thorough elucidation of the hydrogen generation process through water electrolysis is provided. Furthermore, a spectrum of innovative strategies aimed at augmenting the performance of molybdenum carbides in the HER milieu is introduced, encompassing cutting-edge techniques such as phase-transition engineering, the construction of heterostructures, hetero-atom doping, the integration of hybrid structures with carbon materials, defect engineering, and meticulous surface modification. The review culminates by underscoring the current challenges and the promising prospects in the advancement of electrocatalysts for hydrogen production, with a dedicated focus on molybdenum carbide-based catalysts.

Synergistic enhancement of surface-doped Mn and Cu-mediated hierarchical reconstruction in Co–Ni–Cu–Mn electrocatalyst for hydrogen production in proton exchange membrane water electrolyzer

Multicomponent electrocatalysts offer inherent advantages because of the synergistic effects among their constituents at the atomic scale, rendering them suitable for enhancing the catalytic activity of the hydrogen evolution reaction (HER). In this study, self-supported Co–Ni–Cu–Mn electrocatalysts are deposited on porous carbon paper via one-step electrodeposition. These electrocatalysts exhibit remarkable synergistic enhancements, resulting in both improved acidic HER activity and overall durability. This synergy arises from the development of hierarchical structures triggered by Cu and Mn-doped surface. During HER, Cu leaches from the catalyst surface, while simultaneously, surface-doped Mn synergistically prevents activity degradation and facilitates surface reconstruction. The combination of these interactions helps to achieve a low overpotential of 100 mV at 10 mA cm−2. The Co–Ni–Cu–Mn electrocatalyst is applied as a high-efficient cathode gas diffusion electrode for proton exchange membrane water electrolyzer (PEMWE). The PEMWE single-cell equipped with Pt-free cathode achieves an outstanding performance of 2.57 A cm−2 at 2.0 Vcell, with exceptional stability for 60 h under high current density of 2.0 A cm−2. The successful implementation of the quaternary electrocatalyst highlights its potential for tailoring catalytic properties for hydrogen production, effectively bridging the gap between fundamental understanding and practical realization for cost-efficient PEMWE.

Hierarchically Structured Graphene Aerogel Supported Nickel-Cobalt Oxide Nanowires as an Efficient Electrocatalyst for Oxygen Evolution Reaction.

The rational design of a heterostructure electrocatalyst is an attractive strategy to produce hydrogen energy by electrochemical water splitting. Herein, we have constructed hierarchically structured architectures by immobilizing nickel-cobalt oxide nanowires on/beneath the surface of reduced graphene aerogels (NiCoO2/rGAs) through solvent-thermal and activation treatments. The morphological structure of NiCoO2/rGAs was characterized by microscopic analysis, and the porous structure not only accelerates the electrolyte ion diffusion but also prevents the agglomeration of NiCoO2 nanowires, which is favorable to expose the large surface area and active sites. As further confirmed by the spectroscopic analysis, the tuned surface chemical state can boost the catalytic active sites to show the improved oxygen evolution reaction performance in alkaline electrolytes. Due to the synergistic effect of morphology and composition effect, NiCoO2/rGAs show the overpotential of 258 mV at the current density of 10 mA cm-2. Meanwhile, the small values of the Tafel slope and charge transfer resistance imply that NiCoO2/rGAs own fast kinetic behavior during the OER test. The overlap of CV curves at the initial and 1001st cycles and almost no change in current density after the chronoamperometric (CA) test for 10 h confirm that NiCoO2/rGAs own exceptional catalytic stability in a 1 M KOH electrolyte. This work provides a promising way to fabricate the hierarchically structured nanomaterials as efficient electrocatalysts for hydrogen production.

Nanosheets-assembled hollow N-doped carbon nanospheres encapsulated with ultrasmall NiSe nanoparticles for electrocatalytic hydrogen evolution

Developing highly active and stably non-precious metal electrocatalysts for hydrogen production in alkaline conditions is of paramount importance to hydrogen economy. Herein, nanosheet-assembled hollow nitrogen-doped carbon nanospheres confined with ultrasmall NiSe nanoparticles (NiSe@NC) are synthesized by employing a SiO2 template-assisted approach. As expected, the as-prepared NiSe@NC electrocatalyst delivers an overpotential of 169 mV at the current density of 10 mA/cm2 without iR-correction, and sustains at least 80 h for continuous operation, far outperforming the NiSe-p catalyst in 1 M KOH medium toward hydrogen evolution reaction (HER). The appealing HER performance is mainly ascribed to the synergy effect between hollow nitrogen-doped carbon and highly active NiSe nanoparticles, which improves catalytically active sites, expedites electron transfer rate and optimizes the electronic structure of NiSe@NC nanomaterial. More strikingly, this study presents the feasible insights for constructing robust cost-effective electrocatalysts towards efficient HER in harsh alkaline media.

Boosting hydrogen production via water and urea oxidation using a facile fabricated alkali-etched ZIF-67@Ni(OH)2 electrocatalyst

Designing an operative and stable metal electrocatalyst for hydrogen production via water and urea oxidation has been in the spotlight for the past few years. In this work, we have deposited Ni(OH)2 at various time spans of 1, 3 and 5 h over alkali-etched ZIF-67 via facile strategy. The optimum Ni(OH)2@etched ZIF-67 (5 h) (NEZ-3) heterostructure demonstrates excellent OER and UOR performance with a lower overpotential of 240 mV and 1.32 V, respectively at 10 mA cm−2. Moreover, the NEZ-3 electrocatalyst attains smaller Tafel values of 106 and 35 mV dec−1 with remarkable stability of 60 and 48 h for OER/UOR performance at 10 mA cm−2. Specifically, the two-cell electrolyzer requires a lower cell voltage of 1.73 V (OER) and 1.48 V (UOR) with an excellent durability of 20 h at 10 mA cm−2, respectively. Additionally, the water displacement method is used to examine the 4-electron transfer process (OER) of NEZ-3 electrocatalyst with a Faradaic efficiency of 87.53 %. Notably, the porous structure, introduction of oxygen defects (Ov), higher oxidation state of Ni3+, and abundant active sites in NEZ-3 electrocatalyst are the foremost reasons for the superior electrocatalytic water and urea oxidation reactions. Therefore, this research work delivers a simple methodology in emerging a highly active, stable, and cost-effective multifunctional electrocatalysts towards energy conversion applications.

Ce-Doped TiO2 Fabricated Glassy Carbon Electrode for Efficient Hydrogen Evolution Reaction in Acidic Medium.

The quest for sustainable and clean energy sources has intensified research on the Hydrogen Evolution Reaction (HER) in recent decades. In this study, we have presented a novel Ce-doped TiO2 catalyst synthesized through the sol-gel method, showcasing its potential as a superior electrocatalyst for HER in an acidic medium. Comprehensive characterization through X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Energy dispersive X-ray (EDX), and Raman spectroscopy confirms the successful formation of the catalyst. Electrocatalytic performance evaluation, including open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), and Tafel analysis, demonstrates that GCE-5wt.%CeTiO2 outperforms bare GCE, as well as Ce and TiO2-based electrodes. Kinetic investigations reveal a Tafel slope of 105 mV dec-1, indicating the Volmer step as the rate-determining step. The onset potential for HER at GCE-5wt.%CeTiO2 is -0.16 V vs. RHE, close to the platinum electrode. Notably, the catalyst exhibits a low overpotential of 401 mV to achieve a current density of 10 mA cm-2 with an impressive 95 % Faradaic efficiency. Furthermore, the catalyst demonstrates outstanding durability, maintaining a negligible increase in overpotential during a 14-hour chronoamperometry test. These results have far-reaching implications for the development of cost-effective and efficient electrocatalysts for hydrogen production.

Metal Electrocatalysts for Hydrogen Production in Water Splitting.

The rising demand for fossil fuels and the resulting pollution have raised environmental concerns about energy production. Undoubtedly, hydrogen is the best candidate for producing clean and sustainable energy now and in the future. Water splitting is a promising and efficient process for hydrogen production, where catalysts play a key role in the hydrogen evolution reaction (HER). HER electrocatalysis can be well performed by Pt with a low overpotential close to zero and a Tafel slope of about 30 mV dec-1. However, the main challenge in expanding the hydrogen production process is using efficient and inexpensive catalysts. Due to electrocatalytic activity and electrochemical stability, transition metal compounds are the best options for HER electrocatalysts. This study will focus on analyzing the current situation and recent advances in the design and development of nanostructured electrocatalysts for noble and non-noble metals in HER electrocatalysis. In general, strategies including doping, crystallization control, structural engineering, carbon nanomaterials, and increasing active sites by changing morphology are helpful to improve HER performance. Finally, the challenges and future perspectives in designing functional and stable electrocatalysts for HER in efficient hydrogen production from water-splitting electrolysis will be described.

Evolution of Grain Boundaries Promoted Hydrogen Production for Industrial-Grade Current Density.

The development of efficient and durable high-current-density hydrogen production electrocatalysts is crucial for the large-scale production of green hydrogen and the early realization of hydrogen economic blueprint. Herein, the evolution of grain boundaries through Cu-mediated NiMo bimetallic oxides (MCu-BNiMo), which leading to the high efficiency of electrocatalyst for hydrogen evolution process (HER) in industrial-grade current density, is successfully driven. The optimal MCu0.10-BNiMo demonstrates ultrahigh current density (>2 A cm-2) at a smaller overpotential in 1m KOH (572mV), than that of BNiMo, which does not have lattice strain. Experimental and theoretical calculations reveal that MCu0.10-BNiMo with optimal lattice strain generated more electrophilic Mo sites with partial oxidation owing to accelerated charge transfer from Cu to Mo, which lowers the energy barriers for H* adsorption. These synergistic effects lead to the enhanced HER performance of MCu0.10-BNiMo. More importantly, industrial application of MCu0.10-BNiMo operated in alkaline electrolytic cell is also determined, with its current density reached 0.5 A cm-2 at 2.12V and 0.1 A cm-2 at 1.79V, which is nearly five-fold that of the state-of-the-art HER electrocatalyst Pt/C. The strategy provides valuable insights for achieving industrial-scale hydrogen production through a highly efficient HER electrocatalyst.

Bi-cation incorporated Ni3N nanosheets boost water dissociation kinetics for enhanced alkaline hydrogen evolution activity.

Nickel nitride (Ni3N) is a promising electrocatalyst for the hydrogen evolution reaction (HER) owing to its excellent metallic features and has been demonstrated to exhibit considerable activity for water oxidation. However, its undesirable characteristics as an HER electrocatalyst due to its poor unfavourable d-band energy level significantly limit its water dissociation kinetics. Herein, the HER electrocatalytic activity of Ni3N was prominently enhanced via the simultaneous incorporation of bi-cations (vanadium (V) and iron (Fe), denoted as V-Fe-Ni3N). The optimized V-Fe-Ni3N displays impressive performance with an overpotential of 69 mV at 10 mA cm-2 and good stability in 1.0 M KOH, which is remarkably better than pristine Ni3N, V-doped Ni3N, and Fe-doped Ni3N and considerably closer to a commercial Pt/C catalyst. Based on density functional theory (DFT) studies, V and Fe atoms not only serve as active sites for promoting water dissociation kinetics but also tune the electronic structure of Ni3N to achieve optimized hydrogen adsorption capabilities. This work presents an inclusive understanding of the rational designing of high-performance transition metal nitride-based electrocatalysts for hydrogen production. Its electrocatalytic performance can be significantly enhanced by doping transition metal cations.

Nickel-Based Anode Electrocatalysts for Hydrogen Production

Nickel-Based Anode Electrocatalysts for Hydrogen Production

Promotion of Sulfur Vacancies and Mn Substitution in Few-Layered Molybdenum Disulfide Towards Superior Hydrogen Evolution in Acid

The superior features of hydrogen as an energy source with high energy density (120 MJ kg-1) and zero CO2 emission, makes it a strong candidate for replacing fossil fuels. Recently the European Commission has pledged to invest €470 billion in renewable hydrogen technologies by 2050, with a significant portion of this investment expected to be allocated for the deployment of renewable hydrogen electrolyzers by 2030. Water electrolysis via Proton Exchange Membrane (PEM) with Pt/Pd-based noble metals as a cathode, is currently the most effective method for hydrogen production, but alternatives are highly needed due to the scarcity and the higher cost of these metals. One of the promising classes of electrocatalysts for hydrogen evolution reaction (HER) is transition metal dichalcogenides (TMDs), and among them molybdenum disulfide (MoS2) has shown promising properties as an electrocatalyst for hydrogen production. MoS2 has different phases of 1T, 2H, and 3R with 2H-MoS2 being the most promising electrocatalyst for hydrogen production due to its semiconductive behavior and long-term stability. However, the poor conductivity, large band gap and no active basal plane towards HER limits the applications of 2H-MoS2 for water electrolysis in PEM cells. Strategies such as introduction of defects, S-vacancies, edge engineering and doping can result in enhanced HER activity of 2H-MoS2. Incorporating different transition metals (Ni, Co, Mn, Fe) into MoS2 lattice can increase the number of active sites and improve charge transfer during the electrocatalytic reaction. Based on Density Functional Theory (DFT) studies, insertion of Mn into MoS2 layer can decrease the bandgap to zero, resulting in large number of available electronic states around the Fermi level. In this work we introduce Mn doped MoS2 produced via a cost-effective microwave-assisted solid-state approach to explore the potential of few-layered MoS2, doped with different levels of manganese (5%, 10% and 15% at.) for HER in acidic media. The electrocatalytic activity towards HER reveals that 10% at. Mn incorporation into MoS2 lattice, reduces the overpotential (η10) from 210 mV for pristine MoS2 to 148 mV for 10%Mn-MoS2, respectively. In addition, Tafel slope analysis has confirmed a faster kinetics of 10%Mn-MoS2 (53 mV dec-1) compared to MoS2 (75 mV dec-1) revealing the Volmer–Heyrovsky mechanism as the rate determining step (rds). Further characterization by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and DFT studies show that Mn substitution promotes the creation of sulfur vacancies, which in turn enhances the catalytic activity towards HER. Additionally, the 10% Mn-doped MoS2 demonstrates remarkable activity in a single-cell PEM electrolyzer with long-term durability. This study highlights the potential of Mn doped MoS2 as an efficient, low-cost electrocatalyst for hydrogen production, with implications for the development of a sustainable hydrogen economy. Figure 1

Covalent Attachment of Cobalt Bis(Benzylaminedithiolate) to Reduced Graphene Oxide as a Thin-Film Electrocatalyst for Hydrogen Production with Remarkable Dioxygen Tolerance

Covalent Attachment of Cobalt Bis(Benzylaminedithiolate) to Reduced Graphene Oxide as a Thin-Film Electrocatalyst for Hydrogen Production with Remarkable Dioxygen Tolerance

2023 Colin Garfield Fink Postdoctoral Summer Fellowship – Summary Report: The Effect of Electrochemical Hydrogen Production and Storage in Ti3C2T x MXene on Cell Pressure

Hydrogen is a clean fuel that can power vehicles with high efficiency and produce water as the only byproduct. However, hydrogen technologies face challenges that include low volumetric storage capacity. One way to increase volumetric capacity is to store hydrogen in solid state materials. MXenes represent the fastest-growing family of 2D transition metal carbides and nitrides. Owning to their attractive properties, such as redox-active surfaces, metallic conductivity, and hydrophilicity, MXenes have been intensively studied for applications in electrocatalysis and electrochemical energy storage. Recently, Ti2CTx MXene was claimed to store over 8 wt% hydrogen. Since MXenes are also electrocatalysts for hydrogen production, investigating hydrogen storage while it is produced on the same material electrode is a promising direction. In this study, we investigated the effect of electrochemical hydrogen production and storage in Ti3C2Tx MXene on cell pressure in a sulfuric acidic electrolyte.

Designing Efficient Non-Precious Metal Electrocatalysts for High-Performance Hydrogen Production: A Comprehensive Evaluation Strategy.

Developing abundant Earth-element and high-efficient electrocatalysts for hydrogen production is crucial in effectively reducing the cost of green hydrogen production. Herein, a strategy by comprehensively considering the computational chemical indicators for H* adsorption/desorption and dehydrogenation kinetics to evaluate the hydrogen evolution performance of electrocatalysts is proposed. Guided by the proposed strategy, a series of catalysts are constructed through a dual transition metal doping strategy. Density Functional Theory (DFT) calculations and experimental chemistry demonstrate that cobalt-vanadium co-doped Ni3N is an exceptionally ideal catalyst for hydrogen production from electrolyzed alkaline water. Specifically, Co,V-Ni3N requires only 10 and 41mV in alkaline electrolytes and alkaline seawater, respectively, to achieve a hydrogen evolution current density of 10mAcm-2. Moreover, it can operate steadily at a large industrial current density of 500mAcm-2 for extended periods. Importantly, this evaluation strategy is extended to single-metal-doped Ni3N and found that it still exhibits significant universality. This study not only presents an efficient non-precious metal-based electrocatalyst for water/seawater electrolysis but also provides a significant strategy for the design of high-performance catalysts of electrolyzed water.

Mutual promotion by structural design and intrinsic activity coupling of CNTs/MoC/CoNiMo for water splitting and urea electrolysis

Construction of durable multi-function electrocatalysts for hydrogen production is still highly challenging. Herein, we report a hierarchical integrated tri-functional heterogeneous CNTs/MoC/CoNiMo electrode for HER and related OER/UOR. The carbon-protected Ni nanoparticles yield abundant γ-NiOOH active intermediates to boost OER/UOR, while DFT calculations verify Mo migration induced by MoC and CoNiMo alloy under negative potentials generates HER super-active sites on Mo-rich surfaces. Additionally, the parallel aligned nanosheets with out-plane extended CNTs arrays can guide the rapid bubbles release and expand the accessible surface area. Therefore, the optimized CNT/MoC/NMC-3 electrode can achieve overpotentials of 51 mV (HER) and 226 mV (OER), with low potential threshold of 1.257 V (UOR) at 10 mA cm–2. Moreover, the assembled symmetric urea electrolyzer reaches a 1.291 V cell voltage at 10 mA cm–2. This work provides a novel strategy for heterostructure multi-component integration for achieving high-efficiency hydrogen production and urea-containing wastewater purification.

High‐Performance Alkaline Freshwater and Seawater Hydrogen Catalysis by Sword‐Head Structured Mo2N‐Ni3Mo3N Tunable Interstitial Compound Electrocatalysts

AbstractRealizing efficient electrocatalysts is a stepping stone toward achieving high‐performance alkaline water/seawater electrolysis, but remains a crucial challenge. Herein, heterogeneous Mo2N/Ni3Mo3N electrocatalysts on nickel foam (denoted MN‐NMN/NF) that is stable and active for the hydrogen evolution reaction (HER) in both alkaline water/seawater are demonstrated. The optimized MN‐NMN09/NF achieves an ultralow HER overpotential of 11 mV@10 mA cm−2 in 1.0 m KOH electrolyte, which is not only superior to the benchmark Pt/C catalysts but also the best reported ever among NiMo‐based electrocatalysts in an alkaline environment. Successively, the optimized MN‐NMN09/NF electrocatalyst can drive HER current densities of 10 and 500 mA cm−2 using low overpotentials of 9.37 and 123 mV in 1.0 m KOH seawater electrolyte, which remains durable after 120 h long‐term electrolysis at a constant current density of 500 mA cm−2. In situ Raman analysis reveals that the enhanced performance is attributed to the accelerated H2O adsorption and OH dissociation processes on the MN‐NMN surfaces. Theoretical analysis further confirms that rapid H2O adsorption‐dissociation kinetics and H adsorption‐conversion kinetics on the Ni3Mo3N/NiOOH and Ni3Mo3N/MoOx surfaces result in boosted HER capability. This work depicts a significant potential for designing stable and efficient hydrogen production electrocatalysts for both alkaline water and seawater electrolysis.