Ultrathin carbon coated mesoporous Ni-NiFe2O4 nanosheet arrays for efficient overall water splitting

Abstract Developing low-cost, highly efficient electrocatalysts for water splitting is a crucial and challengeable task to produce clean hydrogen fuel. Here, for the first time, we reported a novel ultrathin carbon layer coated mesoporous Ni-NiFe2O4 (Ni-NiFe2O4@C) nanosheet arrays catalyst by hydrothermal growth of NiFe-precursor on carbon cloth followed by a thermal decomposition process. The resultant Ni-NiFe2O4@C catalyst displays excellent electrocatalytic performances toward both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline electrolyte, which requires overpotential of 212 mV for OER and 217 mV for HER to reach 10 mA cm−2 with Tafel slope of 51 and 96 mV dec−1, respectively. Moreover, the two-electrode electrolyzer made of Ni-NiFe2O4@C electrodes requires a cell voltage of 1.57 V to deliver a current density of 10 mA cm−2 with long-term stability, which is superior to that of RuO2//Pt/C electrolyzer. This work offers new insight into the design and development of transition metal-based oxides catalysts for overall water splitting.