Cr selectively incorporated N, S-doped carbon layer encapsulating Ir/IrO 2 for efficient alkaline hydrogen and oxygen evolution

To improve the limited kinetics of alkaline hydrogen evolution reaction (HER), herein, a three-dimensional porous catalyst has been constructed based on the design concept of bi-directional electron modulation and chemical environment regulation of non-metallic and oxophilic transition metal elements with obvious differences in electronegativity on hybrid carbon layer-coated iridium/iridium oxide heterostructure. The Ir/IrO 2 @(N,S)-C possesses significantly superior catalytic activity and electrochemical stability towards alkaline HER with an overpotential of 150 mV reaching 50 mA cm −2 from LSV curve and an increment of 63 mV after 200 h of degradation test at 10 mA cm −2 in 1 M KOH, much lower than 277 mV and an elevation of 116 mV just after 25 h in 0.5 M H 2 SO 4. The strongly electronegative non-metallic elements effectively modulate the electronic states of iridium/iridium oxide, the ratio of metallic states, and the oxophilic environment of the carbon layer, which enables the catalyst surface favorable for the moderate adsorption of water molecules and intermediates. The material engineering strategy offers a new insight for the development of high-performance catalysts towards water electrolysis based on homologous active species.