Theoretical evaluation and experimental investigation of layered 2H/1T-phase MoS2 and its reduced graphene-oxide hybrids for hydrogen evolution reactions

Abstract

We used a one-pot reaction to prepare mixed phase (2H-1T) molybdenum sulfide (MoS2) and reduced graphene oxide (rGO) hybrids as electrocatalysts, which offer unique characteristics for hydrogen evolution reaction (HER) in acidic and alkaline solution. Mixed phase MoS2 and rGO hybrid were characterized using related techniques. Nitrogen isotherm profiles confirmed the improved active surface area with mesoporous structure for 2H-1T MoS2/rGO hybrid. HER outcomes displayed the low overpotentials (-70 and -71 mV vs RHE), achieving 10 mA.cm(-2) current density with the small Tafel slopes (46 and 52 mV.dec(-1)) for 2H-1T MoS2/rGO hybrid in acidic and alkaline electrolyte, respectively. Robust HER characteristic was identified in acid and alkaline solution over 24 h by chronoamperometric studies for 2H-1T MoS2/rGO electrocatalysts. Density functional theory (DFT) estimations identified density of states variations for 2H-1T MoS2 and rGO hybrid hydrogen adsorbed surfaces. DFT calculation extracted the low Gibbs energy of -0.01 eV which evidently confirming the improved experimental HER results for 2H-1T MoS2/rGO hybrid. (C) 2021 Elsevier B.V. All rights reserved.