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Ruthenium (Ru)‐based catalysts, with considerable performance and desirable cost, are becoming highly interesting candidates to replace platinum (Pt) in the alkaline hydrogen evolution reaction (HER). The hydrogen binding at Ru sites (Ru−H) is an important factor limiting the HER activity. Herein, density functional theory (DFT) simulations show that the essence of Ru−H binding energy is the strong interaction between the 4dz2 orbital of Ru and the 1s orbital of H. The charge transfer between Ru sites and substrates (Co and Ni) causes the appropriate downward shift of the 4dz2 ‐band center of Ru, which results in a Gibbs free energy of 0.022 eV for H* in the RuCo system, much lower than the 0.133 eV in the pure Ru system. This theoretical prediction has been experimentally confirmed using RuCo alloy‐nanosheets (RuCo ANSs). They were prepared via a fast co‐precipitation method followed with a mild electrochemical reduction. Structure characterizations reveal that the Ru atoms are embedded into the Co substrate as isolated active sites with a planar symmetric and Z‐direction asymmetric coordination structure, obtaining an optimal 4dz2 modulated electronic structure. Hydrogen sensor and temperature program desorption (TPD) tests demonstrate the enhanced Ru−H interactions in RuCo ANSs compared to those in pure Ru nanoparticles. As a result, the RuCo ANSs reach an ultra‐low overpotential of 10 mV at 10 mA cm−2 and a Tafel slope of 20.6 mV dec−1 in 1 M KOH, outperforming that of the commercial Pt/C. This holistic work provides a new insight to promote alkaline HER by optimizing the metal‐H binding energy of active sites. [ABSTRACT FROM AUTHOR]

The sluggish kinetics of oxygen evolution reaction (OER) is the main bottleneck for the electrocatalytic water splitting to produce hydrogen (H2), and the by‐product is worthless O2. Therefore, designing a thermodynamically favorable oxidation reaction to replace OER and coupling with value‐added product generation on the anode is of significance for boosting H2 generation under low electrolysis voltage. Herein, cobalt hydroxide@hydroxysulfide nanosheets on carbon paper (Co(OH)2@HOS/CP) are synthesized as bifunctional electrocatalysts to facilitate H2 production and convert methanol to valuable formate simultaneously. Benefiting from the influences/changes on the composition, surface properties, electronic structure, and chemistry of Co(OH)2, the as‐obtained electrodes exhibit very high selectivity for methanol to value‐added formate oxidation (MFO) and boost electrocatalytic performance with low overpotential of 155 mV for MFO and 148 mV for hydrogen evolution reaction at a current density of 10 mA cm−2. Furthermore, the integrated two‐electrode electrolyzer drives 10 mA cm−2 at a cell voltage of 1.497 V with united 100% Faradaic efficiency for anodic and cathodic reaction and continuous 20 h of operation without obvious decay. The electrocatalytic hydrogen production with the assistance of alternative oxidation by the robust electrocatalyst can be further used to realize the upgrading of other organic molecules with less energy consumption. [ABSTRACT FROM AUTHOR]

Development of high-performance and stable electrocatalysts for hydrogen evolution reaction (HER) is crucial for hydrogen economy. Inspired by hydrogen evolution behavior on hydrogenase enzyme, in which the azadithiolate bridging ligand of active center facilitates fast proton shuttling and catalytic turnover, here we present an efficient approach to enhance both HER kinetics and stability realizing on an IrNi@N,O-C catalyst with individual IrNi nanoparticle separately confined in N and O co-doped carbon (N,O-C) nanocage. Experimental and theoretical investigations indicate that the N,O-C nanocage provides proton-adsorbing functionality on raising H* coverage over IrNi active centers, resulting in much accelerated HER kinetics. The IrNi@N,O-C presents superior HER performances compared to all reported Ir-based catalysts, with overpotential of 22 mV at 100 mA cm−2, ultrahigh mass activity of 9.82 A mg Ir −1 (−0.050 V vs. RHE) and outstanding durability of 200 h at large current density. This work affords fresh insights/strategies for design of high-performance electrocatalysts [Display omitted] • The IrNi@N,O-C prepared via reactive template route features nanoreactor structure. • The IrNi@N,O-C presents record-high hydrogen evolution reaction performances. • The N,O-C nanocage-mediated HER pathway contributes to enhanced HER performances. • The HER pathway on IrNi@N,O-C is similar to that of hydrogenase enzyme. [ABSTRACT FROM AUTHOR]

The well-designed heterostructured CoP/CN/Ni with oriented electron transfer from the inner Ni to the outer CoP shows excellent electrocatalytic hydrogen evolution and oxygen reduction performances. [Display omitted] • Electronic structure of outer CoP is modulated by the electrons from Ni through CN. • The value of ΔG H* on electron modulated CoP decreases from −0.25 eV to −0.1 eV. • CN layer protects the inner Ni from oxidation and corrosion in harsh environment. • Enriched electrons around CoP weakens its surface oxidation at high potential. Cobalt phosphide (CoP) with its platinum-group-metal like catalytic features has triggered substantial concerns on electrocatalytic hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) under acidic and alkaline conditions. However, the electrocatalytic rate on CoP is restricted because of the reaction intermediates binding to its surface strongly, leading to sluggish reaction kinetics and unsatisfied catalytic performance. Herein, we describe a ternary heterostructured CoP/CN/Ni catalyst with oriented electron modulation effect to boost its electrocatalytic activity, where the electronic structure of the outer CoP is modulated by the endowed electrons from underlying Ni nanoparticles, which are encapsulated and protected by 2–3 N-doped carbon (CN) layers from oxidation and corrosion in harsh environment. Theoretical calculations reveal that the electron redistribution effect could decrease the adsorption energy of hydrogen (ΔG H*) on CoP from −0.25 eV to −0.1 eV. Benefiting from such electron modulation, CoP/CN/Ni only needs overpotentials of 66 mV in 0.5 M H 2 SO 4 and 106 mV in 1 M KOH for HER to afford a current density of 10 mA cm−2 and presents the comparable ORR activity with Pt/C in 0.1 M KOH. Besides, the unique structure also endows CoP/CN/Ni with superior electrocatalytic stability for HER and ORR. [ABSTRACT FROM AUTHOR]

• Remarkable electrocatalytic activity towards both HER and OER. • Excellent performance as bifunctional catalysts in full water splitting. • Finite-element simulations confirm a localized electric field at Ni/Mo-Ni. • The OH– adsorption measurements demonstrate the localized electric field. Hydrogen production by alkaline water electrolysis represents an effective route for low-cost and clean energy conversion. However, as hydrogen ions (H+) are the minority species in alkaline media, the kinetics of hydrogen evolution reaction (HER) is markedly reduced. Concurrently, the transport of hydroxide ions (OH–) is limited under large current density in alkaline oxygen evolution reaction (OER). Herein, Ni nanoparticles-decorated Mo-Ni microrods (Ni/Mo-Ni) are adopted to boost the ion adsorption. Finite-element simulations suggest that a strong local electric field around the Ni nanoparticles exponentially increases ion adsorption towards the electrode surface, which facilitates reaction kinetics and mass transfer for HER at the cathode and OER at the anode. Thus, the Ni/Mo-Ni electrode exhibits a low overpotential of only −24 mV for HER and + 215 mV for OER to reach the current density of 10 mA cm−2, and can achieve an industrial alkaline splitting current density of 100 mA cm−2 at a low voltage of 1.76 V and stably operate for 87 h. This work suggests a new paradigm in the design and engineering of high-performance catalysts for alkaline electrolyzers. [ABSTRACT FROM AUTHOR]