Acidic Hydrogen Evolution Reaction Research Articles

Enhanced acidic hydrogen evolution reaction kinetics via nitrogen-doped iridium nanosheet with optimized hydrogen adsorption energy

The hydrogen evolution reaction (HER) is influenced by the adsorption/desorption of hydrogen intermediates on active sites. Nitrogen doping is a way to alter the electronic structure and boost the activity of metal electrocatalysts although the mechanism remains controversial. Here, nitrogen is incorporated into face-centered cubic iridium nanosheets (N-fcc-Ir-NSs) through the ammonia reduction of metastable two-dimensional pristine trigonal iridium oxide. With a nitrogen content of only 0.8 wt%, N-fcc-Ir-NSs exhibit a low overpotential of 19 mV at −10 mA cmgeo-2 and a Tafel slope of 18.6 mV dec-1 in sulfuric acid. The doped nitrogen reduces hydrogen adsorption energy by modulating the electronic structure of iridium atoms, and the combined effects of iridium sites with strong hydrogen adsorption energy and iridium sites near the nitrogen atoms with weak hydrogen adsorption energy improve the HER activity. Moreover, the presence of nitrogen causes iridium to donate more electrons to hydrogen and promotes hydrogen desorption.

Pt-Decorated bimetallic PdRu nanocubes with tailorable surface electronic structures for highly efficient acidic hydrogen evolution reaction

Efficient and stable catalysts are crucial for green hydrogen production from acidic water splitting. Herein, using interface engineering, the surface electronic structures of bimetallic PdRu nanocubes have been significantly regulated by Pt atoms (PdRu@Pt). Interestingly, Pt atoms are located on the corners and facets of PdRu nanocubes, resulting in lattice tension and fast electron transfer. As a result, the obtained trimetallic PdRu@Pt nanocubes with an average size of 13 nm have exhibited highly enhanced catalytic activity and stability for hydrogen evolution reaction (HER) in acidic media, delivering 18 mV lower overpotential to reach a current density of 10 mA cm−2, and maintaining a remarkable long-term stability for up to 24 h. In particular, the lower overpotential of 489 mV at 500 mA cm−2 for PdRu0.04@Pt0.12 nanocubes indicates its potential for future industrial application in the future. Such enhancements in HER performance can be attributed to the highly facet-edge-exposed Pt atoms and the significant strain effects resulting from the introducing Pt atomic layers to PdRu surfaces.

Operando Spectroscopic Monitoring of Metal Chalcogenides for Overall Water Splitting: New Views of Active Species and Sites

AbstractMetal‐based chalcogenides exhibit great promise for overall water splitting, yet their intrinsic catalytic reaction mechanisms remain to be fully understood. In this work, we employed operando X‐ray absorption (XAS) and in situ Raman spectroscopy to elucidate the structure–activity relationships of low‐crystalline cobalt sulfide (L−CoS) catalysts toward overall water splitting. The operando results for L−CoS catalyzing the alkaline hydrogen evolution reaction (HER) demonstrate that the cobalt centers in the bulk are predominantly coordinated by sulfur atoms, which undergo a kinetic structural rearrangement to generate metallic cobalt in S−Co−Co−S moieties as the true catalytically active species. In comparison, during the acidic HER, L−CoS undergoes local structural optimization of Co centers, and H2 production proceeds with adsorption/desorption of key intermediates atop the Co−S−Co configurations. Further operando characterizations highlight the crucial formation of high‐valent Co4+ species in L−CoS for the alkaline oxygen evolution reaction (OER), and the formation of such active species was found to be far more facile than in crystalline Co3O4 and Co‐LDH references. These insights offer a clear picture of the complexity of active species and site formation in different media, and demonstrate how their restructuring influences the catalytic activity.

Operando Spectroscopic Monitoring of Metal Chalcogenides for Overall Water Splitting: New Views of Active Species and Sites.

Metal-based chalcogenides exhibit great promise for overall water splitting, yet their intrinsic catalytic reaction mechanisms remain to be fully understood. In this work, we employed operando X-ray absorption (XAS) and in situ Raman spectroscopy to elucidate the structure-activity relationships of low-crystalline cobalt sulfide (L-CoS) catalysts toward overall water splitting. The operando results for L-CoS catalyzing the alkaline hydrogen evolution reaction (HER) demonstrate that the cobalt centers in the bulk are predominantly coordinated by sulfur atoms, which undergo a kinetic structural rearrangement to generate metallic cobalt in S-Co-Co-S moieties as the true catalytically active species. In comparison, during the acidic HER, L-CoS undergoes local structural optimization of Co centers, and H2 production proceeds with adsorption/desorption of key intermediates atop the Co-S-Co configurations. Further operando characterizations highlight the crucial formation of high-valent Co4+ species in L-CoS for the alkaline oxygen evolution reaction (OER), and the formation of such active species was found to be far more facile than in crystalline Co3O4 and Co-LDH references. These insights offer a clear picture of the complexity of active species and site formation in different media, and demonstrate how their restructuring influences the catalytic activity.

Crystalline Phase Engineering to Modulate the Interfacial Interaction of the Ruthenium/Molybdenum Carbide for Acidic Hydrogen Evolution.

Ruthenium (Ru) is an ideal substitute to commercial Pt/C for the acidic hydrogen evolution reaction (HER), but it still suffers from undesirable activity due to the strong adsorption free energy of H* (ΔGH*). Herein, we propose crystalline phase engineering by loading Ru clusters on precisely prepared cubic and hexagonal molybdenum carbide (α-MoC/β-Mo2C) supports to modulate the interfacial interactions and achieve high HER activity. Advanced spectroscopies demonstrate that Ru on β-Mo2C shows a lower valence state and withdraws more electrons from the support than that of Ru on α-MoC, indicative of a strong interfacial interaction. Density functional theory reveals that the ΔGH* of Ru/β-Mo2C approaches 0 eV, illuminating an enhancement mechanism at the Ru/β-Mo2C interface. The resultant Ru/β-Mo2C exhibits an encouraging performance in a proton exchange membrane water electrolyzer with a low cell voltage (1.58 V@ 1.0 A cm-2) and long stability (500 h@ 1.0 A cm-2).

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.

In Situ Engineering Multifunctional Active Sites of Ruthenium-Nickel Alloys for pH-Universal Ampere-Level Current-Density Hydrogen Evolution.

Developing robust non-platinum electrocatalysts with multifunctional active sites for pH-universal hydrogen evolution reaction (HER) is crucial for scalable hydrogen production through electrochemical water splitting. Here ultra-small ruthenium-nickel alloy nanoparticles steadily anchored on reduced graphene oxide papers (Ru-Ni/rGOPs) as versatile electrocatalytic materials for acidic and alkaline HER are reported. These Ru-Ni alloy nanoparticles serve as pH self-adaptive electroactive species by making use of in situ surface reconstruction, where surface Ni atoms are hydroxylated to produce bifunctional active sites of Ru-Ni(OH)2 for alkaline HER, and selectively etched to form monometallic Ru active sites for acidic HER, respectively. Owing to the presence of Ru-Ni(OH)2 multi-site surface, which not only accelerates water dissociation to generate reactive hydrogen intermediates but also facilitates their recombination into hydrogen molecules, the self-supported Ru90Ni10/rGOP hybrid electrode only takes overpotential of as low as ≈106mV to deliver current density of 1000mAcm-2, and maintains exceptional stability for over 1000h in 1 m KOH. While in 0.5 m H2SO4, the Ru90Ni10/rGOP hybrid electrode exhibits acidic HER catalytic behavior comparable to commercially available Pt/C catalyst due to the formation of monometallic Ru shell. These electrochemical behaviors outperform some of the best Ru-based catalysts and make it attractive alternative to Pt-based catalysts toward highly efficient HER.

Screening of transition metal dual-atom catalysts for hydrogen evolution reaction based on high-throughput calculation and searching surrogate prediction model using simple features

Dual-atom catalysts for hydrogen evolution reaction have received widespread attention, but precise screening and prediction of high-performance catalysts through simple methods remains a challenge. In this study, we perform high-throughput density functional theory (DFT) calculation and machine learning (ML) to screen and predict the transition metal dual-atom catalysts with N-doped graphene support (TMDACs) for acidic hydrogen evolution reaction (HER). The Fe_Zn and V_Fe DACs were proposed to be the most promising candidates for Pt-based catalyst toward acidic HER from 406 TMDACs, based on the characteristics of HER activity, formation, thermodynamic stability, abundance, environmental friendliness. The Fe_Zn and V_Fe DACs with excellent HER performance is due to the synergistic effect deriving from the interaction between H and dual metal atoms in TMDACs. By determining 6 different ML models with four kind of input features, we find the artificial neural networks (ANN) model can predict the HER performance of TMDACs most accurately only using simple input features, including one-hot-encoding of atomic number and Gibbs free energies of transition metal single-atom catalysts. This work not only proposed the potential TMDACs with high HER performance, but also verified that the ANN model can accurately predict the HER activity of diatomic catalysts with simple input features.

Modulating Pt‐N/O Bonds on Co‐doped WO3 for Acid Electrocatalytic Hydrogen Evolution with Over 2000 h Operation

AbstractDeveloping durable electrocatalysts with high performance for hydrogen evolution reaction (HER) in acid conditions is of prime challenge for hydrogen production. Durability is of important prerequisite for catalyst application. Herein, this work constructs the Co‐doped WO3 loaded with Pt nanoparticles under ammonia treatment (Pt/N‐CoWO3) with the Pt‐N/O‐W interaction, which shows excellent activity and stability for acidic hydrogen production at industrial current density. The electronic structure of Pt species is modulated with enhanced Pt‐N/O bonding by Co doping, hence reinforcing the metal‐support interaction, and greatly enhancing the stability of the catalyst under high current density in acidic media. The resultant Pt/N‐CoWO3 catalyst exhibits the overpotentials of only 94 and 108 mV at high current densities of 1 and 2 A cm−2, respectively. More impressively, Pt/N‐CoWO3 delivers a record operation for acid electrocatalytic hydrogen evolution over 2000 h at 1 A cm−2, denoting its potential for catalyst applications at the industrial current density. This work opens a new avenue for developing Pt‐loading acidic HER catalysts for long‐term operation at ampere‐level current densities in acid conditions.

Small-sized Ni-Co/Mo2C/Co6Mo6C2@C for efficient alkaline and acidic hydrogen evolution reaction by an anchoring calcination strategy

Small-sized Ni-Co/Mo2C/Co6Mo6C2@C for efficient alkaline and acidic hydrogen evolution reaction by an anchoring calcination strategy

Synergistic Effects of Dual-Doping with Ni and Ru in Monolayer VS2 Nanosheet: Unleashing Enhanced Performance for Acidic HER through Defects and Strain.

Amidst the escalating quest for clean energy, the hydrogen evolution reaction (HER) in acidic conditions has taken center stage, catalyzing the search for advanced electrocatalysts. The efficacy of these materials is predominantly dictated by the active site density on their surfaces. The propensity is leveraged for monolayer architectures to introduce defects, enhancing surface area, and increasing active sites. Doping enhances defects and fine-tunes catalyst activity. In this vein, defect-enriched monolayer nanosheets doped with nickel and a trace amount of ruthenium in VS2 (SL-Ni-Ru-VS2 ) are engineered and characterized. Evaluation in 0.5m H2 SO4 solution unveils that the catalyst achieves overpotentials as low as 20 and 41mV at current densities of -10 and -100mA cm⁻2 . Impressively, the catalyst maintains a mass activity of 13.08 A mg⁻¹Ru , even with minimal Ru incorporation, indicating exceptional catalytic efficiency. This monolayer catalyst sustains its high activity at lower overpotentials, demonstrating its practical applicability. The comprehensive analysis, which combines experimental data and computational simulations, indicates that the co-doping of Ni and Ru enhances the electrocatalytic properties of VS2 . This research offers a strategic framework for crafting cutting-edge electrocatalysts specifically designed for enhanced performance in the HER.

Pt nanodendrites with a PtIr alloy surface structure exhibit excellent stability toward acidic hydrogen evolution reaction

Pt nanodendrites with a PtIr alloy surface structure exhibit excellent stability toward acidic hydrogen evolution reaction

Electrocatalytic Activation in ReSe2-VSe2 Alloy Nanosheets to Boost Water-Splitting Hydrogen Evolution Reaction.

It is challenging to control the electronic structure of 2D transition metal dichalcogenides (TMD) for extended applications in renewable energy devices. Here, ReSe2-VSe2 (Re1- xVxSe2) alloy nanosheets over the whole composition range via a colloidal reaction is synthesized. Increasing x makes the nanosheets more metallic and induces a 1T″-to-1T phase transition at x = 0.5-0.6. Compared to the MoSe2-VSe2 and WSe2-VSe2 alloy nanosheets, ReSe2 and VSe2 are mixed more homogeneously at the atomic scale. The alloy nanosheets at x = 0.1-0.7 exhibit an enhanced electrocatalytic activity toward acidic hydrogen evolution reaction (HER). In situ X-ray absorption fine structure measurements reveal that alloying caused the Re and V atoms to be synergically more active in the HER. Gibbs free energy (ΔGH*) and density of state calculations confirm that alloying and Se vacancies effectively activate the metal sites toward HER. The composition dependence of HER performance is explained by homogenous atomic mixing with the increased Se vacancies. The study provides a strategy for designing new TMD alloy nanosheets with enhanced catalytic activity.

Switch Volmer-Heyrovsky to Volmer-Tafel Pathway for Efficient Acidic Electrocatalytic Hydrogen Evolution by Correlating Pt Single Atoms with Clusters.

As cost-effective catalysts, platinum (Pt) single-atom catalysts (SACs) have attracted substantial attention. However, most studies indicate that Pt SACs in acidic hydrogen evolution reaction (HER) follow the slow Volmer-Heyrovsky (VH) mechanism instead of the fast kinetic Volmer-Tafel (VT) pathway. Here, this work propose that the VH mechanism in Pt SACs can be switched to the faster VT pathway for efficient HER by correlating Pt single atoms (SAs) with Pt clusters (Cs). Ourcalculations reveal that the correlation between Pt SAs and Cs significantly impacts the electronic structure of exposed Pt atoms, lowering the adsorption barrier for atomic hydrogen and enabling a faster VT mechanism. To validate these findings, this work purposely synthesize three catalysts: l-Pt@MoS2, m-Pt@MoS2 and h-Pt@MoS2 with low, moderate, and high Pt-loading, having different distributions of Pt SAs and Cs. The m-Pt@MoS2 catalyst with properly correlating Pt SAs and Cs exhibits outstanding performance with an overpotential of 47mV and Tafel slope of 32mV dec-1. Further analysis of the Tafel values confirms that the m-Pt@MoS2 sample indeed follows the VT reaction mechanism, aligning with the theoretical findings. This study offers a deep understanding of the synergistic mechanism, paving a way for designing novel-advanced catalysts.

Designing AgBi3S5 as an efficient electrocatalyst for hydrogen evolution reaction

Nano-catalysts Ag2S, Bi2S3, AgBi3S5 and CuBiS2 are synthesized by facile hot chemical treatments and used for electrochemical hydrogen evolution reaction in acid. The best catalyst AgBi3S5 can be designed for generation of green fuel hydrogen.

Synthesis of high-entropy alloy nanoparticles using microwave-assisted reduction and investigation of their enhanced electrochemical hydrogen evolution activity

Abstract High-entropy alloys (HEAs) are fascinating materials for novel catalysts because of their broad compositional space, which is enabled by entropy-driven mixing. Herein, HEA nanoparticles (NPs) containing Fe, Co, Ni, Cu, and Pd were successfully synthesized on reduced graphene oxide (rGO) by microwave-assisted reduction. Compared with the corresponding monometallic catalysts, the quinary FeCoNiCuPd/rGO demonstrated greater electrocatalytic activity toward the acidic hydrogen evolution reaction. Density functional theory calculations revealed that modification of the d-band center and the hydrogen affinity induced by multielemental mixing enhanced the electrocatalytic performance of the HEA.

Efficient Alkaline Hydrogen Evolution Reaction Using Superaerophobic Ni Nanoarrays with Accelerated H2 Bubble Release

Water electrolysis for producing green hydrogen is of central importance in the hydrogen economy to meet the global mission of carbon neutrality. Hydrogen evolution reaction (HER) under alkaline conditions has many advantages in cost and stability over acidic HER, but it requires high overpotential due to sluggish reaction kinetics. Pt-based materials are still considered the benchmark for HER catalysts, however, their high cost is the major hurdle for large-scale applications, motivating tremendous efforts to find earth-abundant catalytic materials as alternatives.In addition to catalytic materials, the formation and release of H2 bubbles on the surface of catalysts should be considered when designing efficient catalysts, as this significantly affects catalytic performance. Adhered H2 bubbles on the catalyst surface can cause reduced active surface sites, blockage of ion pathways, and destruction of catalyst film by inducing a large stretch force. Despite the adverse effects of H2 bubbles adhering to catalyst’s surface on the performance of water electrolysis, the mechanisms by which H2 bubbles are effectively released during the alkaline HER remain elusive.In this study, we conducted a systematic investigation on the effect of nanoscale surface morphologies on H2 bubble release behaviors and HER performance by employing earth-abundant Ni catalysts consisting of an array of Ni nanorods (NRs) with controlled surface porosities. Both aerophobicity and hydrophilicity of the catalyst’s surface vary according to the surface porosity of catalysts. The Ni catalyst with the highest porosity of ~52% exhibits superaerophobic nature as well as the best HER performance among the Ni catalysts. It was found that the Ni catalyst’s superaerophobicity combined with the effective open pore channels enables the accelerated release of H2 bubbles from the surface, leading to a significant improvement in geometric activities, particularly at high current densities, as well as intrinsic activities including both specific and mass activities. It was also demonstrated that the superaerophobicity enabled by highly porous Ni NRs can be combined with Pt and Cr having optimal binding abilities to further optimize electrocatalytic performance. Our work can help to elucidate the fundamental and practical design rules for efficient alkaline HER catalysts consisting of earth-abundant elements.

Controllable Electrochemical Liberation of Hydrogen from Sodium Borohydride.

Sodium borohydride (NaBH4 ) has earned recognition as a promising hydrogen carrier, attributed to its exceptional hydrogen storage capacity, boasting a high theoretical storage capacity of 10.8 wt %. Nonetheless, the utilization of traditional pyrolysis and hydrolysis methods still presents a formidable challenge in achieving controlled hydrogen generation especially under ambient conditions. In this work, we report an innovative electrochemical strategy for production H2 by coupling NaBH4 electrooxidation reaction (BOR) at anode in alkaline media with hydrogen evolution reaction (HER) at cathode in acidic media. To implement this, we have developed a bifunctional electrocatalyst denoted as Pd-Mo2 C@CNTs, wherein Pd nanoparticles are grown in situ on Mo2 C embedded within N-doped carbon nanotubes. This electrocatalyst demonstrates exceptional performance in catalyzing both alkaline BOR and acidic HER. We have developed a hybrid acid/alkali cell, utilizing Pd/Mo2 C@CNTs as the anode and cathode electrocatalysts. This configuration showcases remarkable capabilities for self-sustained, precise, and uninterrupted indirect release of H2 stored in NaBH4 , even at high current densities of 100 mA cm-2 with a Faraday efficiency approaching 100 %. Additionally, this electrochemical device exhibits significant promise as a fuel cell, with the ability to deliver a maximum power density of 20 mW cm-2 .

Controllable Electrochemical Liberation of Hydrogen from Sodium Borohydride

AbstractSodium borohydride (NaBH4) has earned recognition as a promising hydrogen carrier, attributed to its exceptional hydrogen storage capacity, boasting a high theoretical storage capacity of 10.8 wt %. Nonetheless, the utilization of traditional pyrolysis and hydrolysis methods still presents a formidable challenge in achieving controlled hydrogen generation especially under ambient conditions. In this work, we report an innovative electrochemical strategy for production H2 by coupling NaBH4 electrooxidation reaction (BOR) at anode in alkaline media with hydrogen evolution reaction (HER) at cathode in acidic media. To implement this, we have developed a bifunctional electrocatalyst denoted as Pd‐Mo2C@CNTs, wherein Pd nanoparticles are grown in situ on Mo2C embedded within N‐doped carbon nanotubes. This electrocatalyst demonstrates exceptional performance in catalyzing both alkaline BOR and acidic HER. We have developed a hybrid acid/alkali cell, utilizing Pd/Mo2C@CNTs as the anode and cathode electrocatalysts. This configuration showcases remarkable capabilities for self‐sustained, precise, and uninterrupted indirect release of H2 stored in NaBH4, even at high current densities of 100 mA cm−2 with a Faraday efficiency approaching 100 %. Additionally, this electrochemical device exhibits significant promise as a fuel cell, with the ability to deliver a maximum power density of 20 mW cm−2.

Boron-induced construction of two-dimensional layered Mo/Mo2C electrocatalyst to boost both alkaline and acidic hydrogen evolution reaction

High-performance non-precious-metal electrocatalysts for the hydrogen evolution reaction (HER) in both acidic and alkaline media are urgently required to replace expensive Pt-based catalysts. Herein, we report an effective molten salt-assisted boron-induced phase transformation strategy for the preparation of boron-doped Mo/Mo2C (B–Mo/Mo2C). The B–Mo/Mo2C electrocatalyst maintains two-dimensional (2D) layered structure of the precursor material to expose more catalytic active sites. Due to the suitable doping and the successful construction of the heterostructure, the efficient electron transfer between Mo and Mo2C is generated and its electronic structure is reasonably regulated. The obtained B–Mo/Mo2C electrocatalyst exhibits excellent HER performance with overpotentials of 108 mV (η10) and 191 mV (η10) in 1.0 M KOH and 0.5 M H2SO4 solutions, respectively. These results demonstrate the efficiency of the noble-metal-free B–Mo/Mo2C electrocatalyst and highlight its broad applicability.