Stable and high-performance Ir electrocatalyst with boosted utilization efficiency in acidic overall water splitting

Abstract

The industrialization of solid polymer electrolyte water electrolysis (SPEWE) dominantly relies on electrocatalyst with high stability and efficiency for oxygen evolution reaction (OER) catalysis. In this work, we report a facile method to construct α-Ni(OH)2@Ir core–shell nanoparticles as bifunctional electrocatalyst for acidic overall water splitting application. α-Ni(OH)2@Ir requires lower overpotentials (238 mV and 20 mV) to achieve 10 mA cm−2 in acidic OER and HER catalysis compared to benchmarked IrO2 (332 mV) and Pt/C (36 mV); meanwhile, the OER mass activity at 1.55 V vs. RHE was 92 fold higher than IrO2; HER mass activity at overpotential of 80 mV was 5 fold better than Pt/C. The boosted catalytic activity is due to the enhanced utilization efficiency of Ir stemmed from the ultrathin Ir shell (~1 nm). Moreover, 1.49 V is demanded for α-Ni(OH)2@Ir to attain 10 mA cm−2 in acidic overall water splitting, 110 mV lower than benchmarked Pt/C-IrO2 system. Meanwhile, stable catalytic performance is recorded for 20 h.