Fabrication and evaluation of a self-standing reduced graphene-tungsten oxides hybrid electrode for acidic water splitting

摘要

Adsorption isotherm suggested the formation of mesoporous structural design within a 3D self-assembled SA-GWO architecture electrode. Bi-functional (HER and OER) activity has been displayed by SA-GWO electrodes at the combined full potential of 1.9 V and attains the standard 10 mA/cm2 (1 M H2SO4, 28 degrees C). Remarkably, it exhibits OER activity in the acidic medium, which is so far very limited. The tafel slope and the exchange current density for the HER process are observed to be 117 mV/decade and 1.73 x 10-3 mA/cm2, respectively, at 28 degrees C. Importantly, the production rate of hydrogen is found to increase with increasing temperature. HER is highly dominated by the Volmer route. Gas liberated at the respective electrode has been tested via gas chromatography (GC) analysis. SA-GWO supports the faradaic efficiency of 73 and 52% for HER and OER, respectively. Tafel slope for OER appeared to be very high owing to its complex mechanistic pathway. Disintegra-tion of 3D monoclinic WO3 and the formation of 2D nanochannels like nanostructure have been distinctly observed in SEM micro images, when the electrode is subjected to cathodic HER reaction (-0.5 V, 1 M H2SO4). Most importantly, the WO3 polymorph typically responsible for the distinct mechanism of HER and OER action in 1 M H2SO4 has been identified and proven. Moreover, the 3D SA-GWO electrode as HER possesses great endurance and incomparable stability in acidic media.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.