Electrocatalysis through interface and structural engineering of hollow/porous NiSe/CoSe2 nanotubes for overall water splitting

Nickel/cobalt-based selenides is considered as a promising electrocatalyst for overall water splitting ascribed to rapid electron transfer ability and long-term durability. However, the sluggish water dissociation kinetics and high Gibbs free energy seriously hinder its actual application. Herein, interface engineering is proposed to promote the formation of high-valence metal cations, thus activating the active center of electrocatalytic water dissociation and reducing the adsorption/desorption free energy of the intermediates significantly. In addition, a stable hollow mesoporous structure is constructed through structural engineering, which provides abundant accessible inner and outer surfaces, and the capillary phenomenon caused by the hollow structure promotes the adsorption of water molecules in the reaction center and the desorption of gases. Based on the coupling effect described above, the hollow/porous NiSe/CoSe2-100 nanotubes (denoted as NiSe/CoSe2-X HNTs, X is the weight of Se powder) demonstrate an overpotential of 117 and 225 mV for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Meanwhile, the system of NiSe/CoSe2-100 HNTs//NiSe/CoSe2-100 HNTs requires a low voltage of 1.46 V to drive water splitting and the faraday efficiency is close to 100%. Overall, a new route is proposed for the construction of electrocatalysts with fast hydrolysis kinetics.