In situ synthesis of Fe2O3/Fe3O4 nanoarray hybrid as highly effective electrocatalysts for alkaline hydrogen evolution

It is of great importance to rationally develop and design cost-effective, high durable and non-noble metal catalysts for electrocatalytic water splitting. Here, self-supported well-defined crystalline iron oxides hybrid (FeOx/IF) was successfully fabricated by facile in-situ thermal air oxidation of iron foam. An investigation into the effects of thermal oxidation temperature on the crystalline structure and surface appearance of FeOx/IF was studied. The resultant FeOx/IF-550 reveals nanoarrays morphology composed of Fe2O3 and Fe3O4 hybrid with Fe2O3 and Fe3O4 heterojunctions, which exhibits remarkably superior catalytic activity towards HER with a low overpotential of only 98 mV to drive a current density of 10 mA cm-2 in alkaline solution. Meanwhile, FeOx/IF-550 exhibits good durability with negligible attenuation of overpotential at a large current density of 500 mA cm-2 for 24 h in alkaline solution. The excellent HER performance of FeOx/IF is mainly attributed to the synergistic effect of Fe2O3 and Fe3O4, increased accessible active sites and accelerated charge transfer. The present study provides new insights into the design of cost-effective electrocatalysts with high activity and excellent stability for industrialization.