Ionic Liquid-Assisted Synthesis of Nanoscale (MoS2)x(SnO2)1-x on Reduced Graphene Oxide for the Electrocatalytic Hydrogen Evolution Reaction

Sudhir Ravula; Chi Zhang; Jeremy B Essner; J David Robertson; Jian Lin; Gary A Baker

doi:10.1021/acsami.6b13578

Ionic Liquid-Assisted Synthesis of Nanoscale (MoS₂)_x(SnO₂)_1-x on Reduced Graphene Oxide for the Electrocatalytic Hydrogen Evolution Reaction

ACS Appl Mater Interfaces. 2017 Mar 8;9(9):8065-8074. doi: 10.1021/acsami.6b13578. Epub 2017 Feb 21.

Authors

Sudhir Ravula¹, Chi Zhang², Jeremy B Essner¹, J David Robertson^{1

3}, Jian Lin², Gary A Baker¹

Affiliations

¹ Department of Chemistry, University of Missouri , Columbia, Missouri 65211, United States.
² Department of Mechanical & Aerospace Engineering, University of Missouri , Columbia, Missouri 65211, United States.
³ University of Missouri Research Reactor, University of Missouri , Columbia, Missouri 65211, United States.

PMID: 28187262
DOI: 10.1021/acsami.6b13578

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 MoS_2(1-x)Se_2x or bimetallic sulfides, have arisen as promising electrocatalysts compared to MoS₂ and MoSe₂ due 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 SnO₂ phase) greatly reduces the overpotential by 90-130 mV relative to the MoS₂ electrocatalyst. Significantly, the (MoS₂)_0.6(SnO₂)_0.4/rGO nanohybrid displays superior catalytic performance over MoS₂ alone, 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.

Keywords: electrocatalysis; hydrogen evolution reaction; ionic liquids; reduced graphene oxide; transition metal dichalcogenides.