Engineering water splitting sites in three-dimensional flower-like Co–Ni–P/MoS2 heterostructural hybrid spheres for accelerating electrocatalytic oxygen and hydrogen evolution

Abstract

Enhancing the kinetics of electrocatalytic water splitting, including the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), under alkaline conditions is of key importance for producing high purity and renewable hydrogen on a large scale. Owing to their unique structural features, two-dimensional (2D) heterostructures have been regarded as promising next-generation electrocatalysts for overall water splitting. Herein, we successfully synthesized three-dimensional (3D) flower-like Co–Ni–P/MoS₂ heterostructural hybrid spheres assembled from heterostructural 2D nanosheets. Benefiting from well-exposed interfaces and favorable diffusion channels, the as-prepared 3D flower-like Co–Ni–P/MoS₂ heterostructural hybrid spheres manifest excellent overall water splitting performance in an alkaline solution with a low Tafel slope of 71 and 41 mV dec⁻¹ for oxygen and hydrogen evolution reactions, and show significantly improved long-term durability. Furthermore, the 3D flower-like Co–Ni–P/MoS₂ heterostructural hybrid spheres used in both the anode and cathode show a low cell voltage of 1.53 V at a 10 mA cm⁻² current density. Using DFT calculations, we found the outstanding chemisorption of hydrogen and oxygen-containing intermediates making Co–Ni–P/MoS₂ heterostructures an efficient bifunctional overall electrochemical water splitting catalyst. In summary, this work opens up an important direction for exploring efficient and durable bifunctional electrocatalysts for the overall water splitting.