High‐pressure microwave‐assisted synthesis of WS <sub> <i>x</i> </sub> /Ni <sub>9</sub> S <sub>8</sub> /NF hetero‐catalyst for efficient oxygen evolution reaction
Xue Ma, Xinyu Zhang, Min Yang, Jingyi Xie, Ren‐Qing Lv, Yong‐Ming Chai, Bin Dong
Abstract
Abstract Designing the specific crystal phase with better intrinsic activity and more active sites is a very promising strategy for earth‐abundant electrocatalysts for oxygen evolution reaction (OER). Herein, a facile two‐step method including the high‐pressure microwave and the hydrothermal sulfurization is adopted to prepare the WS x /Ni 9 S 8 hetero‐catalyst on nickel foam (WS x /Ni 9 S 8 /NF). Firstly, WO 3 polyhedrons homogeneously cover the surface of NF through the high‐pressure microwave hydrothermal process. Secondly, WS x /Ni 9 S 8 nanoparticles on the surface of NF can be synthesized after a hydrothermal sulfurization, which has been confirmed by scanning electron microscopy (SEM) elemental mapping and high‐resolution transmission electron microscopy (HRTEM). The amorphous WS x and Ni 9 S 8 phase may provide the dual active sites for OER. The electrochemical measurements show that WS x /Ni 9 S 8 /NF has superior OER activity with a low overpotential of 320 mV at the current density of 100 mA·cm −2 , better than those of other samples. The enhanced OER performance may be due to the synergistic catalysis from Ni 9 S 8 phase and high valence of W. Owing to the stable structure of Ni 9 S 8 , the long‐term stability of WS x /Ni 9 S 8 /NF for at least 10 h can be obtained. This work may provide a new approach for the doped nickel sulfides crystal phase through high‐pressure microwave hydrothermal assistance for OER.