title: Ionic Liquid-Assisted Synthesis of Nanoscale (MoS2)x(SnO2)1-xon Reduced Graphene Oxide for the Electrocatalytic Hydrogen Evolution Reaction.
abstract: Layered transition metal dichalcogenides (TMDs) have attracted increased attention due to their enhanced hydrogen evolution reaction (HER) performance. More specifically, ternary TMD nanohybrids, such as MoS2(1-x)Se2xor bimetallic sulfides, have arisen as promising electrocatalysts compared to MoS2and MoSe2due to their electronic, morphologic, and size tunabilities. Herein, we report the successful synthesis of few-layered MoS2/rGO, SnS2/rGO, and (MoS2)x(SnO2)1-x/rGO nanohybrids anchored on reduced graphene oxide (rGO) through a facile hydrothermal reaction in the presence of ionic liquids as stabilizing, delayering agents. Spectroscopic and microscopic techniques (electron microscopy, X-ray diffraction, Raman spectroscopy, neutron activation analysis, and UV-vis spectrophotometry) are used to validate the hierarchical properties, phase identity, and the smooth compositional tunability of the (MoS2)x(SnO2)1-x/rGO nanohybrids. Linear sweep voltammetry measurements reveal that incorporation of Sn into the ternary nanohybrids (as a discrete SnO2phase) greatly reduces the overpotential by 90-130 mV relative to the MoS2electrocatalyst. Significantly, the (MoS2)0.6(SnO2)0.4/rGO nanohybrid displays superior catalytic performance over MoS2alone, exhibiting a low overpotential (η10) of 263 ± 5 mV and a small Tafel slope of 50.8 mV dec-1. The hybrid catalyst shows high stability for the HER in acidic solutions, with negligible activity loss after 1000 cycles. The hierarchical structures and large surface areas possessing exposed, active edge sites make few-layered (MoS2)x(SnO2)1-x/rGO nanohybrids promising nonprecious metal electrocatalysts for the HER.
authors.affiliation: Department of Chemistry, University of Missouri , Columbia, Missouri 65211, United States.
authors.forename: Sudhir
authors.initials: S
authors.lastname: Ravula
authors.affiliation: Department of Mechanical & Aerospace Engineering, University of Missouri , Columbia, Missouri 65211, United States.
authors.forename: Chi
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, University of Missouri , Columbia, Missouri 65211, United States.
authors.forename: Jeremy B
authors.identifier: http://orcid.org/0000-0002-2500-7968
authors.initials: JB
authors.lastname: Essner
authors.affiliation: Department of Chemistry, University of Missouri , Columbia, Missouri 65211, United States.|University of Missouri Research Reactor, University of Missouri , Columbia, Missouri 65211, United States.
authors.forename: J David
authors.initials: JD
authors.lastname: Robertson
authors.affiliation: Department of Mechanical & Aerospace Engineering, University of Missouri , Columbia, Missouri 65211, United States.
authors.forename: Jian
authors.initials: J
authors.lastname: Lin
authors.affiliation: Department of Chemistry, University of Missouri , Columbia, Missouri 65211, United States.
authors.forename: Gary A
authors.identifier: http://orcid.org/0000-0002-3052-7730
authors.initials: GA
authors.lastname: Baker
keywords: electrocatalysis; hydrogen evolution reaction; ionic liquids; reduced graphene oxide; transition metal dichalcogenides