Constructing hierarchical structure electrocatalyst for efficient hydrogen evolution and selective oxidation of benzylamine

Abstract

Replacing oxygen evolution reaction (OER) with thermodynamically favorable oxidation reactions is a promising strategy to enhance the cathodic hydrogen production. In this paper, Mo doped CoNi metal-organic framework (MOF)-layered double hydroxide (LDH) nanosheet supported on Ni foam was constructed. The obtained MOF@LDH-Mo heterostructure array possessed large tangible surface area, rich active species and open electron transport channels, which was employed as electrocatalyst for benzylamine oxidation reaction (BOR) to replace OER for boosting hydrogen evolution. Benefitting from the unique structures, the MOF@LDH-Mo presented unprecedented intrinsic activity toward BOR, a high current density of 325 mA cm −2 can be reached at 1.7 V (vs RHE) in 1 mol·L −1 KOH solution. Meanwhile, the cell voltage decreased sharply, especially compared with that of overall water splitting (e.g. a reduction of 260 mV for the benchmark current density of 100 mA cm −2 ). Apart from H 2 production at cathode, value added chemical, benzonitrile, was yielded at anode with high Faradaic efficiency. This research provides an environmental friendly aqueous electrocatalytic route for production of valuable chemicals as well as green energy, hydrogen. The synthetic process of CoNi-MOF@LDH-Mo contains two steps. Firstly, CoNi-MOF nanoarrays were grown directly on nickel foam via hydrothermal process. Then, the CoNi-MOF@LDH-Mo was obtained by electro-depositing Mo-doped LDH on the surface of CoNi-MOF arrays.