Advanced Mott-Schottky heterojunction of semi-conductive MoS₂ nanoparticles/metallic CoS2 nanotubes as an efficient multifunctional catalyst for urea-water electrolysis

Metallic CoS2 has attracted considerable interest for the catalysis of electrochemical reactions; however, its catalytic activity is still lower than that of commercial novel metal-based catalysts. Semiconductive 2H-MoS2 also holds a high capability for catalysis. In this work, a rationally designed Mott-Schottky heterojunction of ultrasmall MoS2 nanoparticles/CoS2 nanotube arrays is constructed via an effective synthetic protocol. Because of the difference in the Fermi level of the metallic CoS2 and semiconducting MoS2, strong Mott-Schottky interaction occurs at their heterointerface to gain equalization, resulting in the optimization of intermediates adsorption energies, thereby favoring the reaction kinetics of hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and urea oxidation reaction (UOR). Consequently, the proposed catalyst yields high current densities at small HER and OER overpotentials or low UOR potentials, small Tafel slopes, and desirable stability, confirming its excellent electrocatalytic activities for these key half-reactions toward significantly boosting water and urea electrolysis.