H-H dimer intermediates redefining hydrogen evolution electrocatalysis

Anion-regulated cobalt coordination polymer: Construction, electrocatalytic hydrogen evolution and L-cysteine electrochemical sensing

Electrocatalytic water splitting reaction is a sustainable method for producing hydrogen at a large scale, which provides a promising pathway for energy transition. However, electrocatalyst activity remains a limitation restricting the energy conversion efficiency of water electrolysis systems. In this study, a three-dimensional hierarchical heterostructure electrocatalyst with vertically aligned NiFe layered double hydroxides (LDH) nanoflakes/Fe-NiS <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> nanoparticles supported on biomass-derived carbons was constructed. The experimental results proved that the catalyst has good activity and duralibity toward electrocatalytic hydrogen evolution in alkaline solutions. The electrode exhibits an electrocatalytic activity requiring an overpotential of 169 mV for delivering a current density of targeted 10 mA•cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> in HER; catalytic activity does not decay significantly within 15 h. Combined with the calculation results of density functional theory, the unique three-dimensional configuration of the catalyst, the high conductivity of the carbon microtube support, and the strong coupling effect at the interface between NiFe LDH and Fe-NiS <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> accelerates electron/ion transfer, further facilitating the reaction kinetics of hydrogen evolution.

Efficient hydrogen evolution via electrocatalytic water splitting holds great promise in modern energy devices. Herein, we demonstrate that the localized surface plasmon resonance (LSPR) excitation of Au nanorods (NRs) dramatically improves the electrocatalytic hydrogen evolution activity of CoFe-metal-organic framework nanosheets (CoFe-MOFNs), leading to a more than 4-fold increase of current density at -0.236 V (vs. RHE) for Au/CoFe-MOFNs composite under light irradiation versus in dark. Mechanistic investigations reveal that the hydrogen evolution enhancement can be largely attributed to the injection of hot electrons from AuNRs to CoFe-MOFNs, raising the Fermi level of CoFe-MOFNs, facilitating the reduction of H2 O and affording decreased activation energy for HER. This study highlights the superiority of plasmonic excitation on improving electrocatalytic efficiency of MOFs and provides a novel avenue towards the design of highly efficient water-splitting systems under light irradiation.

The electrochemical behavior of ad-atoms and their effect on hydrogen evolution Part III. Platinum ad-atoms on gold, and gold ad-atoms on platinum

Electrocatalysis of hydrogen evolution in the light of the brewer—engel theory for bonding in metals and intermetallic phases

Synergistic effect of reduced graphene oxide and near-infrared light on MoS2-mediated electrocatalytic hydrogen evolution

Two nickel-based catalysts, TBA2[NiII(mnt)2] 1 and TBA[NiIII(mnt)2] 2 are formed by the reactions of NiCl2·6H2O, Na2(mnt), and tetra-n-butylammoniumbromide (TBABr) without or with iodine (I2) (mnt = 2,2-dicyanoethylene-1,1-dithiolate), respectively. Under an overpotential (OP) of 941.6 mV, complexes 1 and 2 can electrocatalyze hydrogen evolution from acetic acid with a turnover frequency (TOF) of 36.3 and 148.31 mol H2/mol catalyst/h, respectively. Under blue light (λ max = 469 nm), 1 or 2, together with CdS nanorods (CdS NRs) as a photosensitizer, and ascorbic acid (H2A) as a sacrificial electron donor, can produce hydrogen with a turnover number (TON) of 7760 and 17,570 moles of H2 per mole of catalyst during 35 h irradiation, respectively. The average value of apparent quantum yield (AQY) is ∼9.2% (complex 1) and 28% (complex 2), respectively. The results indicate that the nickel(III) complex has a better active activity for hydrogen production than the nickel(II) species.

Density functional calculations along with in situ X‐ray absorption spectroscopy data show that AuPd alloys form unique potential‐controlled surface structures during the hydrogen evolution. We find evidence for surface segregations preferring a gold surface if the surface is free of chemisorbed species, while hydrogen adsorption triggers palladium segregation into the surface.

Electrocatalytic hydrogen evolution and sulfion (S2−) recycling are promising strategies for boosting H2 production and removing environmental pollutants. Here, a nano‐Ni‐functionalized molybdenum disulfide (MoS2) nanosheet was assembled on steel mesh (Ni‐MoS2/SM) for use in sulfide oxidation reaction‐assisted, energy‐saving H2 production. Experimental and theoretical calculation results revealed that anchoring nano‐Ni on high‐surface‐area slack MoS2 nanosheets not only optimized catalyst adsorption of polysulfides but also played an important role in promoting hydrogen evolution reaction kinetics by absorbing OHad, thereby greatly enhancing the catalytic performance toward sulfide oxidation reaction and hydrogen evolution reaction. Meanwhile, the Ni/MoS2‐based hydrogen evolution reaction + sulfide oxidation reaction system achieved nearly 100% hydrogen production efficiency and only consumed 61% less power per kWh than the oxygen evolution reaction + hydrogen evolution reaction system, which suggested our proposed Ni‐MoS2 and novel hydrogen production system are promising for sustainable energy production.

The precise control over the geometric and electronic structures of active materials on flexible substrates is of great importance to address the current challenges in optimizing and developing high-performance flexible devices for energy conversion and storage. In this work, an addressable surface was demonstrated to engineer structurally controllable active nanomaterials for electrocatalytic hydrogen evolution. The nanostructures of WS2/MOF/metal hydroxide/oxide with different formation energy barriers electrodes could be tuned by modifying the ratio of O/C and the concentration of carbon defects at the surface of carbon cloth. The morphological structure of the vertical WS2 nanosheets that are favorable to electrocatalysis was found to be highly related to the addressable surface of carbon cloth though heterogeneous nucleation and the interactions between the monomers and surface functional groups. Moreover, the electronic structure of WS2 was further modified with N doping (N-WS2) to deliver an addressable surface for the reaction species involved in the electrocatalytic hydrogen evolution reaction (HER), and the resultant N-WS2 exhibited enhanced HER activity compared with the original WS2. The systematic experimental research and electronic-structure density functional theory (DFT) calculations demonstrated the interesting features of the N dopant: (i) the strong hybridization of the p orbital of dopant N with d orbital of W and p orbital of S atoms (W d-S p-N p hybridization) close to the Fermi level can disperse the conducting charges, thus leading to an improved conductivity across the basal plane of WS2 nanosheets; (ii) the local electron transfer from W to N atoms provides the local charge, thus promoting the H adsorption process in the HER for N-WS2. Our research can be expected to offer new perspectives in the precise construction of highly reactive nanostructures toward high-efficiency and highly stable flexible devices for energy conversion and storage.

The electrochemical properties of [Formula: see text]-octaethylporphycene iridium complex (Ir-OEPo) were determined. Based on the electro-spectro measurement results, the reduction of Ir-OEPo did not occur at the central metal but at the ligand, while the reduction of [Formula: see text]-octaethylporphyrin iridium complex (Ir-OEPor) occurred at the central iridium. A catalytic current was observed during the cyclic voltammetry (CV) measurements with trifluoroacetic acid (TFA) under a reductive condition, indicating the catalytic reactivity of Ir-OEPo for the hydrogen evolution reaction (HER). By constant potential electrolysis, hydrogen gas was detected by gas chromatography (GC) and the catalytic reactivity of Ir-OEPo was confirmed. The HER mechanism via ligand reduction of macrocyclic aromatic complexes could be one of the concepts for the development of new catalysts.

Transition metal phosphides (TMPs) have been extensively and deeply researched as electrode materials for energy‐related applications. However, the inferior stability is still a bottleneck restricting their substantive development. Herein, a freestanding three‐dimensional hierarchical nanostructure (marked as CC@NC/NiCo‐P) is delicately designed for high‐performance supercapacitors and electrocatalytic hydrogen evolution, where the nitrogen‐doped carbon (NC) layer derived from polydopamine serves as an interface coupling bridge for anchoring electroactive nickel cobalt phosphide (NiCo‐P) nanowire arrays on flexible carbon cloth (CC) substrate. Thanks to the robust interaction between the conductive carbon support and NiCo‐P nanowires, the resultant CC@NC/NiCo‐P electrode delivers an ultrahigh capacitance (2175.5 F/g at 1 A/g) and a distinguished rate capability with a capacity retention of 85.8%. The assembled asymmetric supercapacitor can achieve a superior energy density of 28.47 Wh/kg and an ultralong lifespan of 10 000 cycles. In addition, the CC@NC/NiCo‐P electrode shows favorable electrocatalytic activity toward the hydrogen evolution reaction. These results indicate that the strong binding between the NC layer and metal species in TMPs notably improves the stability and electrochemical activity of CC@NC/NiCo‐P. It is expected that this effective strategy to design innovative electrode materials may be promising for the applications in energy‐related fields.

Electrocatalytic hydrogen evolution on metallic and bimetallic Pd–Co alloy nanoparticles

Electrochemical water splitting towards hydrogen production is of significance for our sustainable development in the future. Although platinum‐group catalysts possess the highest activity for hydrogen evolution reaction (HER), their scarcity renders potential applications commercially inviable and thus many efforts are constantly devoted into this arena. Over the last decade, various molybdenum‐based catalysts, covering, for example, sulfides, carbides, phosphides, borides, nitrides and alloys, have been found to be very active, and are rapidly becoming popular. In this Review, we comprehensively summarize this topic of emerging Mo‐based catalysts for HER by stating and discussing their catalytic mechanisms, synthesis methods, optimization tactics, and promise to outbalance platinum‐based systems. We use typical examples from recent advances of various Mo‐based catalysts to elaborate their merits and shortcomings for HER, as well as how to further optimize their activities, varying from surface area maximization and active site exposure to electron/atom/molecule/phase‐level manipulation, and to external field‐assisted activity enhancement. We also propose various challenges and perspectives for these emerging Mo‐based catalysts and discuss how these challenges might be addressed.

Electrocatalytic hydrogen evolution by cobalt(Ⅲ) triphenyl corrole bearing different number of trifluoromethyl groups