Hydroxyl-regulated CoMoO nanotubes as an efficient bifunctional electrocatalyst for the hydrogen/oxygen evolution reaction.

CoMoO bimetallic oxides have been regarded as promising electrocatalysts for the electrocatalytic hydrogen/oxygen evolution reaction (HER/OER) due to the synergistic interaction between the superior conductivity of Mo and the excellent redox capacity of Co. Surface atom tailoring has been widely applied to adjust the electronic structure and thereby promote the electrocatalytic performance of CoMoO. However, the introduction of functional groups to improve the surface electrocatalytic active sites and electronic structure of CoMoO has been scarcely reported. Hydroxyl radicals play a significant role in surface electrocatalytic reactions. Thus, an appropriate surface engineering strategy can be used to efficiently promote the response of CoMoO to hydroxyl radicals. For instance, erythritol possesses numerous hydroxyl groups, which is selected herein to regulate the surface structures and electrocatalytic performance of CoMoO nanotubes. Erythritol-regulated CoMoO (CoMoO-E) nanotubes exhibit more active sites, demonstrate favorable electron interaction, facilitate charge transfer and ion transport, and enhance hydrogen/oxygen gas diffusion. Thus, CoMoO-E nanotubes show excellent electrocatalytic HER and OER activities in alkaline solution, exhibiting an HER performance of -87 mV at -10 mA cm and -398 mV at -400 mA cm and an OER performance of 254 mV at 10 mA cm and 407 mV at 150 mA cm. Our findings provide a new insight to facilitate the development of bimetallic oxides and their electrocatalysts for the HER/OER.