Engineering Interface on a 3D CoxNi1-x(OH)2@MoS2 Hollow Heterostructure for Robust Electrocatalytic Hydrogen Evolution.

Clarifying the responsibilities and constructing the synergy of different active phases are of great significance but still an urgent challenge for the heterostructure catalyst to improve the hydrogen evolution reaction (HER) process. Here, three-dimensional (3D) CoxNi(1-x)(OH)2 hollow structure integrating MoS2 nanosheet catalysts [CoxNi(1-x)(OH)2@MoS2] were ingeniously designed and prepared. This unique structure has realized the construction of a dual active phase for the optimized stepwise-synergetic hydrogen evolution process over a universal pH range through interface assembly engineering. Meanwhile, the 3D hollow heterostructure with a high surface-to-volume ratio can effectively avoid the agglomeration of MoS2 and enhance the CoxNi(1-x)(OH)2-MoS2 heterointerfaces. Thus, superior HER activity and stability were obtained over the universal pH range. Density functional theory calculation reveals that CoxNi(1-x)(OH)2 and MoS2 phases provide efficient active sites for rate-determining water dissociation and H* adsorption/H2 generation on CoxNi(1-x)(OH)2-MoS2 heterointerfaces, respectively, resulting in an optimized energy barrier for HER. This work proposes a constructive strategy to design highly efficient electrocatalysts based on the heterointerface with a defined responsible active phase of electrocatalysts.