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Alloying is regarded as one of the most promising strategies for boosting performance of catalysts for hydrogen evolution reaction (HER) due to the adjustable electronic structure and intermediate adsorption. However, there is no theory (including d‐band center theory) can accurately guide the preparation and design of alloy catalysts, and thus resulting all the reported alloy catalysts are obtained by time‐consuming and laborious experimental exploration. Herein, we proposed a mean d‐band center (εas) as a new accurate descriptor for alloy activity prediction. Theoretical simulation and experiment results revealed that this descriptor exhibits a strong scaling relation with H adsorption energy. Besides, the obtained Cu–Ag alloy displays an optimal overpotential of 223 mV at 10 mA/cm2 in 0.5 mol/L H2SO4, which is more than 300 mV lower than those of pristine Cu (530 mV) and Ag (569 mV) powder. Our work provides a new idea toward designing highly efficient HER catalysts and broadens the applicability of d‐band theory to activity prediction of alloys. [ABSTRACT FROM AUTHOR]

Highly active, durable, and cost‐effective electrodes for hydrogen evolution reaction (HER) at ultrahigh current densities (≥1 A cm−2) are extremely demanded for industrial high‐rate hydrogen production, but challenging. Here, a robust strongly coupled Ag(S)@NiO/nickel foam (NF) electrode is reported. Taking advantage of millisecond laser direct writing in liquid nitrogen technique, lattice‐matched and coherent interfaces are formed between Ag nanoparticles with stacking faults (denoted by Ag(S)) and NiO nanosheets, leading to strong interfacial electronic coupling, not only promoting H2O adsorption and dissociation on Ni2+ but also enhancing H* adsorption on intrinsically inactive but most electrically conductive Ag. Strong chemical bonding is established at NiO/NF interface, guaranteeing rapid electron transfer and excellent mechanical durability under high‐rate hydrogen evolution. The physicochemically stable electrode achieves record‐low alkaline HER overpotential of 167 and 180 mV at 1 and 1.5 A cm−2, respectively, along with negligible activity decay after 120 h test at ≈1.5 A cm−2, surpassing reported non‐platinum group metal electrocatalysts. [ABSTRACT FROM AUTHOR]

Large‐scale application of alkaline water electrolysis for high‐rate hydrogen production is severely hindered by high electricity cost, mainly due to difficulties to acquire cost‐effective catalytic electrodes with both extremely low overpotential and long‐term durability at ultrahigh current densities (≥1 A cm−2). Here it is demonstrated that by adopting a synthetic method of laser direct writing in liquid nitrogen via a commercial laser welding machine, a remarkably efficient and durable electrode with large area and low platinum content is obtained, where PtNi nanocatalysts with dislocation network are firmly welded on a nickel foam (NF). The dense dislocation network not only improves intrinsic activity of a majority of surface‐active sites induced by coupled compressive‐tensile strains synergistically promoting both Volmer and Tafel steps of alkaline hydrogen evolution reaction (HER), but also well stabilizes surface dislocations for HER at ultrahigh current densities. Such a robust electrode achieves record‐low overpotentials of 5 and 63 mV at 10 and 1000 mA cm−2 in alkaline medium, respectively, exhibiting negligible activity decay after 300 h chronoamperometric test at 1 A cm−2. It displays a high Pt mass activity 16 times higher than 20 wt% Pt/C loaded on NF, surpassing most of the recently reported efficient Pt‐based catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • An edge dislocation strain-boosted Ni 3 Mo integrated electrode is developed. • Numerous edge dislocations induce remarkable coupled strain effect in Ni 3 Mo nanoparticles. • Coupled strains inhibit dissolution of Mo atoms in Ni 3 Mo during alkaline HER process. • Coupled strains simultaneously optimize the electronic structure of Ni and Mo sites. • State-of-the-art HER activity and durability in alkaline water/seawater are achieved. The development of NiMo-based electrode with superior activity and durability at high current densities to meet industrial requirements for hydrogen production in alkaline water/seawater still remains a great challenge. Herein, an edge dislocation strain-boosted Ni 3 Mo integrated electrode (D-Ni 3 Mo/NF) is reported. The remarkable coupled tensile-compressive strain effect induced by dense edge dislocations not only inhibits oxidative dissolution of Mo from Ni 3 Mo in alkaline electrolyte, but also simultaneously optimizes the electronic structure of dual active sites (Ni and Mo), which boost both durability and activity of D-Ni 3 Mo in catalyzing alkaline hydrogen evolution reaction (HER). Consequently, D-Ni 3 Mo/NF only requires overpotentials as low as 15 and 232 mV to achieve 10 and 1000 mA cm−2 in 1 M KOH, respectively, and exhibits ultralong-term stability for 200 h at 500 mA cm−2, outperforming most of recently reported NiMo-based catalysts. It also shows distinguished HER activity in seawater electrolysis with superior stability at 500 mA cm−2. [ABSTRACT FROM AUTHOR]

• NiMo/NiCo 2 O 4 hybrid catalysts in-situ grown on nickel foam was prepared. • The synergistic effect of NiMo and NiCo 2 O 4 enhances the catalytic activities. • The NiMo/NiCo 2 O 4 has excellent catalytic activity for overall water splitting. It is highly desirable to develop efficient and low-cost bifunctional HER/OER electrocatalysts for overall water splitting. Herein, Ni 5 Mo/NiCo 2 O 4 heterojunctions loaded on nickel foam were prepared. The catalyst shows excellent bifunctional activity, with an HER overpotential of 44 mV at 10 mA cm−2 and an OER overpotential of 305 mV at 50 mA cm−2 in alkaline electrolyte. In addition, it is worth noting that the overpotential of HER and OER at 500 mA cm−2 are only 229 mV and 368 mV, respectively. It is evidenced that the combination of Ni 5 Mo and NiCo 2 O 4 transfers electrons from Co2+/Co3+ to Ni0/Mo0, which optimizes the electronic structures of the active sites of Ni0, Mo0 and Co3+, thus greatly enhances the intrinsic HER and OER activities. When Ni 5 Mo/NiCo 2 O 4 /NF is used as anode and cathode for water splitting under alkaline conditions, a stable current density of 10 mA cm−2 can be achieved at a low cell voltage of 1.54 V and a long-term stability up to 50 h. This work highlights the synergy effect of alloy and oxide heterojunctions in efficient water electrocatalysis. Due to the optimization of electronic structure of interface metal active sites for reaction intermediates absorption via favorable electronic coupling at the hybrid interface, the overall water splitting activity of NiMo/NiCo 2 O 4 heterojunction was significantly improved. [Display omitted] [ABSTRACT FROM AUTHOR]