Defect engineered 2D mesoporous Mo-Co-O nanosheets with crystalline-amorphous composite structure for efficient oxygen evolution

Abstract

Two-dimensional (2D) mesoporous metal-oxide (hydroxide) nanomaterials with defects are promising towards the realization of efficient electrocatalysis. Herein, we report a facile and effective one-pot solvothermal route to synthesize mesoporous Mox-Co-O hybrid nanosheets (NSs) which is composed of crystalline Mo4O11 and amorphous cobalt hydroxide. Due to the corrosion of 1-octylamine at high temperatures, abundant mesoporous holes are created in situ over the Mox-Co-O hybrid NSs during the solvothermal process, which is beneficial to increasing the electrochemical surface area. The dimension of the Mox-Co-O NSs, size of mesoporous and the concentration of defects can be easily modulated by controlling the molar ratio of Mo/Co. Electrochemical measurements reveal that the 2D mesoporous Mox-Co-O NSs show an excellent activity for the oxygen evolution reaction with the highest catalytic activity of η10 = 276 mV at 10 mA cm−2 in 1 mol L−1 KOH. Enhanced adsorption of intermediates and abundant oxygen vacancies achieved by appropriate Mo doping are the two main factors that contribute to the excellent catalytic activity of Mo0.2-Co-O NSs. This work, with the construction of 2D metal-oxide (hydroxide) crystalline-amorphous nanomaterials possessing abundant holes, oxygen vacancies and enhanced adsorption of intermediates, provides important insight on the design of more efficient catalysts.