Hierarchical construction of hollow NiCo2S4 nanotube@NiCo2S4 nanosheet arrays on Ni foam as an efficient and durable electrocatalyst for hydrogen evolution reaction

Ternary transition metal chalcogenide (TTMC) with multicomponent, different phases and unique electronic structures have been studied in electrocatalytic hydrogen evolution re-action (HER). However, the strong interaction between adsorbed H (H*) and sulfur leads to the unfavorable hydrogen desorption properties of considerable TTMC. Herein, we con-structed the hierarchical hollow NiCo2S4 nanotube@NiCo2S4 nanosheet arrays on Ni foam substrate (NT-NiCo2S4@NS-NiCo2S4/NF) by ion-exchange method. Homogeneous anion diffusion facilitates the formation of regular ultrathin nanosheets on hollow NiCo2S4 nanotube arrays, which presents hierarchical architecture with more surface area and channels to active site exposure, electrolyte diffusion, and gas desorption for HER. As -synthesized optimal NT-NiCo2S4@NS-NiCo2S4/NF electrode demonstrates an excellent HER activity, especially an overpotential of 221 mV, a Tafel slope of 108 mV dec-1, and remarkable stability at current densities of 100 mA cm-2 in 1.0 M NaOH electrolyte.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.