Engineering the interfacial hetero-structure for high-current-density hydrogen evolution

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.