Investigation on microstructural impacts to electrochemical performances of strontium tungstate as efficient bifunctional catalyst for hydrogen and oxygen evolution reactions

The development of efficient bifunctional catalysts with the properties of high-performance, high-stability, earth-abundant, and low-cost for both hydrogen and oxygen evolution reactions (HER/OER) remains a major challenge. Herein, we have proposed simple strategies to construct an efficient bifunctional catalyst with the above properties with the three different morphologies (i.e., dumbbell, proximal phalanges and cinnamon granola bar-like) of strontium tungstate (SrWO4, SrW) microstructures by the coprecipitation (ST), ultra-sonication (SO), and hydrothermal (HT) methods. The physicochemical properties of SrW were investigated by XRD, Raman, FT-IR, FE-SEM, TEM and XPS analysis. Owing to their unique morphologies, the developed SrW catalysts show good HER/OER activity in the alkaline media. In particular, the SO-SrW modified electrode exhibit comparatively better performance with a lower overpotential of 0.66 V at a current density of 10 mA cm(-2) for HER with a small Tafel slope of 138 mV/dec, and the overpotential is 0.50 Vat a current density of 10 mA cm(-2) for OER with a small Tafel slope of 218 mV/dec in 1 M KOH along with excellent stability. These results suggest that the microstructural properties of SrW have a significant impact on their HER/OER catalytic performances, and provide new insights into the development of SrW-based bifunctional catalysts. (C) 2021 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.