High-pressure microwave-assisted synthesis of WSx/Ni9S8/NF hetero-catalyst for efficient oxygen evolution reaction

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 WSx/Ni9S8 hetero-catalyst on nickel foam (WSx/Ni9S8/NF). Firstly, WO3 polyhedrons homogeneously cover the surface of NF through the high-pressure microwave hydrothermal process. Secondly, WSx/Ni9S8 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 WSx and Ni9S8 phase may provide the dual active sites for OER. The electrochemical measurements show that WSx/Ni9S8/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 Ni9S8 phase and high valence of W. Owing to the stable structure of Ni9S8, the long-term stability of WSx/Ni9S8/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.

Automated summary

The study successfully prepared earth-abundant electrocatalysts for the oxygen evolution reaction (OER) by designing crystal phases with better intrinsic activity and more active sites. The WSx/Ni9S8/NF catalyst exhibited superior OER activity and long-term stability, possibly attributed to the synergistic catalysis from the Ni9S8 phase and high valence of W.