Synergistic effect of ascorbic acid on the synthesis of mesoporous rGO-MoS2(100) nanocomposites and promotion of hydrogen evolution reaction

Abstract

Abstract We report a new method for the preparation of MoS2 (100)-reduced graphene oxide (rGO) nanocomposites for enhancement of HER. Ascorbic acid synergistically is applied to reduce graphene oxide and controls the sulfur content of MoS2 resulted in texturing of MoS2 (100) by up taking sulfur and proposing Mo(VI) oxidation state. Variety of characterization were performed to support this hypothesis including XRD, FESEM, TEM, EDX elemental mapping, XPS, Raman, FT-IR and UV–Vis spectroscopies, TGA and BET-BJH analyses. By incorporating ascorbic acid in the synthesis process, the atomic ratio of S Mo is 0.02 for rGO-Mo(VI)S2 hybrid structure with quenched (002) Bragg diffraction peak. rGO-MoS2 shows a net 0.08 mA cm−2 polarized photocurrent in light off-on measurement. A Tafel slope of 44 mV.dec−1, an exchange current of 0.62 mA cm−2, over potential of 156 mV 10 mA cm−2 and onset potential of 25 mV was obtained. This report opens a new pass way in simple and cheap preparation of controlled defective MoS2-rGO structures with new crystal growth (100) of MoS2 for enhanced Hydrogen Evolution Reaction using ascorbic acid. Mechanisms for the role of ascorbic acid on the formation of such defective structure as well as the process of enhancement of HER have been suggested.