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The slow water dissociation process in alkaline electrolyte severely limits the kinetics of HER. The orientation of H2O is well known to affect the dissociation process, but H2O orientation is hard to control because of its random distribution. Herein, an atomically asymmetric local electric field was designed by IrRu dizygotic single‐atom sites (IrRu DSACs) to tune the H2O adsorption configuration and orientation, thus optimizing its dissociation process. The electric field intensity of IrRu DSACs is over 4.00×1010 N/C. The ab initio molecular dynamics simulations combined with in situ Raman spectroscopy analysis on the adsorption behavior of H2O show that the M−H bond length (M=active site) is shortened at the interface due to the strong local electric field gradient and the optimized water orientation promotes the dissociation process of interfacial water. This work provides a new way to explore the role of single atomic sites in alkaline hydrogen evolution reaction. [ABSTRACT FROM AUTHOR]

Activated two-dimension (2D) materials are used in various applications as high-performance catalysts. Breaking the long-range order of the basal plane of 2D materials can highly promote catalytic activity by supplying more active sites. Here we developed a method to synthesize ultrathin MCoOx (M = V, Mn, Fe, Ni, Cu, Zn) amorphous nanosheets (ANSs). These Co-based ANSs show high oxygen evolution reaction (OER) activity in alkaline solution due to the broken long-range order and the presence of abundant low bonded O on the basal plane. The stable Fe1Co1Ox ANSs also show an overpotential of ca. 240 mV of achieving 10 mA/cm2 in OER, better than most reported transition metal-based electrocatalysts. [ABSTRACT FROM AUTHOR]

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]

Abstract Surface modification of nanostructured catalysts is fundamental in accelerating sluggish oxygen evolution reaction (OER). Herein we demonstrate that nanostructured Nickel Selenide (NiSe2) exhibits excellent capability for OER owing to the high compatibility between (200) plane and alkaline solution. The dendrite-like nickel selenide achieves a specific current density of 10 mA/cm2 at an overpotential low to ∼299 mV. The NiSe2 has high stability, in which overpotential decreased ∼2 mV after 10 000 cycles. We demonstrated that the catalytic efficiency of OER could be promoted by increasing the exposure ratio of (200) plane. This work discloses that kinetics of OER are related to specific facets exposure, in which it opens up the possibility of designing active and stable catalysts for OER utilization. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Keywords: Alkaline HER; Atomic Charge Distribution; Interfacial Water Orientation; Single-Atom Site; Water Dissociation EN Alkaline HER Atomic Charge Distribution Interfacial Water Orientation Single-Atom Site Water Dissociation 1 1 1 06/20/23 20230626 NES 230626 B Alkaline water electrolysis b is a promising technology for hydrogen production, but the slow water dissociation process limits the kinetics of the hydrogen evolution reaction (HER). In their Research Article (e202300873), Emiliano Cortés and co-workers designed an atomically asymmetric local electric field using IrRu dizygotic single-atom sites (IrRu DSACs) to optimize the dissociation process by tuning the H SB 2 sb O adsorption configuration and orientation. Inside Back Cover: Atomically Local Electric Field Induced Interface Water Reorientation for Alkaline Hydrogen Evolution Reaction (Angew. [Extracted from the article]

Hydrogen energy as a promising renewable and sustainable energy has attracted growing attentions in recent years, in searching of low-cost electrocatalysts with high efficiency as alternatives of non-noble metals for hydrogen evolution reaction (HER). Herein we report an in-situ cobalt and nitrogen co-doped mesoporous graphitic carbon catalysts by directly pyrolyzing hyperbranched cobalt phthalocyanine (H-CoPc), which can efficiently catalyze HER in acidic, alkaline or neutral electrolytes. With only 0.62 at% of cobalt dopants, the outstanding Co@NG-800 catalyst exhibits excellent durability and HER activities with the overpotential as low as 286 mV in acid, 290 mV in alkaline and 480 mV in neutral, achieved at 10 mA cm −2 current density. These activities indicate that the Co@NG-800 catalyst can couple with the best available oxygen-evolving catalysts in the overall water-splitting. Meanwhile, the mesoporous structure derived from H-CoPc provides more active sites than un-hyperbranched precursor. This work may provide a novel organic metal complexes and simple route in designing highly active and durable transition metal and nitride co-doped carbonaceous electrocatalysts for HER. [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]

Nickel-based selenides are believed to be promising non-precious metal electrocatalysts, and have been widely used for both oxygen evolution reactions (OER) and hydrogen evolution reactions (HER). Here, we control the aging time to prepare NixSey with different fractal structures as a bifunctional catalyst. An obtained sample with an aging time of 80 min shows outstanding electrocatalytic performance for hydrogen evolution reactions (HER) with an overpotential of 225 mV (η@10 mA/cm2) and for oxygen evolution reactions (OER) with an overpotential of 309 mV (η@50 mA/cm2). Moreover, to further improve catalytic activity, we doped Fe in NixSey to obtain the ternary nickel-based selenide, Fe0.2Ni0.8Se (FNSs). The HER activity of FNS increased two-fold at 10 mA/cm2, and the overpotential of OER decreased to 255 mV at 50 mA/cm2. The synthetic strategy and research results of this work have a certain reference value for other low-cost and high-efficiency transition metal catalysts for electrocatalytic water splitting. [ABSTRACT FROM AUTHOR]