The self-reconstruction of Co-modified bimetallic hydroxysulfide nanosheet arrays for efficient hydrazine assisted water splitting

Exploiting low-cost and bifunctional electrodes for the hydrogen evolution reaction (HER) and hydrazine hydrate oxidation (HzOR) is significant for the efficient generation of H2, but still some challenges remain. In this work, the in-situ growth of the Co-modified bimetallic hydroxysulfide (NiFeSOH) nanosheet arrays is realized by a simple aging method. The NiFe foam (NFF) is used as self-sacrificing Ni and Fe sources and happens coupling reaction with the surface-modified Co2+, resulting in the self-reconstruction of hydroxysulfide on NFF. Remarkably, the catalytic active sites and reaction kinetics are optimized by the introduction of Co centers, which endows the catalyst with greatly improved catalytic activity for both HER and HzOR. As a consequence, the Co–FeNiSOH/NFF sample shows low potentials toward HER (−0.266 V) and HzOR (0.355 V) at 100 mA cm−2 in an alkaline medium. In addition, the Co–FeNiSOH/NFF-based electrolyzer realizes small cell voltages of 0.26 V and 0.64 V at the current density of 10 mA cm−2 and 100 mA cm−2, respectively, that outperforms most reported hydroxide materials. Our work develops efficient bifunctional HER/HzOR electrodes, which may provide a promising way for the preparation of the other catalysts in H2 generation.