The lack of available protons severely lowers the activity of alkaline hydrogen evolution reaction process than that in acids, which can be efficiently accelerated by tuning the coverage and chemical environment of protons on catalyst surface. However, the cycling of active sites by proton transfer is largely dependent on the utilization of noble metal catalysts because of the appealing electronic interaction between noble metal atoms and protons. Herein, an all-non-noble W/WO 2 metallic heterostructure serving as an efficient solid-acid catalyst exhibits remarkable hydrogen evolution reaction performance with an ultra-low overpotential of −35 mV at −10 mA/cm 2 and a small Tafel slope (−34 mV/dec), as well as long-term durability of hydrogen production (>50 h) at current densities of −10 and −50 mA/cm 2 in alkaline electrolyte. Multiple in situ and ex situ spectroscopy characterizations combining with first-principle density functional theory calculations discover that a dynamic proton-concentrated surface can be constructed on W/WO 2 solid-acid catalyst under ultra-low overpotentials, which enables W/WO 2 catalyzing alkaline hydrogen production to follow a kinetically fast Volmer-Tafel pathway with two neighboring protons recombining into a hydrogen molecule. Our strategy of solid-acid catalyst and utilization of multiple spectroscopy characterizations may provide an interesting route for designing advanced all-non-noble catalytic system towards boosting hydrogen evolution reaction performance in alkaline electrolyte.
Modulating the hetero-structures with abundant interfaces in catalyst is a feasible but challenging strategy to improve the catalytic performance. In this work, a highly efficient catalyst ( R -CoMoO x /Ni (Co)) was prepared with plentiful interfacial structures to accelerate the hydrogen evolution reaction (HER), which contained both reduced CoO and MoO 2 as a R -CoMoO x substrate and metallic Ni (Co) particles as the catalytic center. The combination of CoO and MoO 2 with a Co-O-Mo local structure in R -CoMoO x led to an electron-enriched Co center to catch the dissociated H + , while the abundant interfacial interaction between R -CoMoO x and Ni (Co) could accelerate the charge transfer and then facilitate the production of H 2 through a fast Volmer-Tafel pathway. As a result, the integrated R -CoMoO x /Ni (Co) catalyst could drive alkaline HER with ultra-low overpotentials of 16 mV for 10 mA cm −2 (25 °C) and 186 mV for 1000 mA cm −2 (60 °C), respectively, with a good stability over 100 h. Moreover, by coupling with RuO 2 electrode in an anion exchange membrane system, it could achieve 1000 mA cm −2 at 1.78 V for overall water splitting with a high energy conversion efficiency of 70.4 %. The H 2 production cost at 1000 mA cm −2 was merely $ 0.952 per gasoline gallon equivalent, much less than the target cost of the US Department of Energy.
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