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

Abstract

• Sol-gel chemical reaction formulated the mixed phase MoS 2 and rGO hybrid structure. • Structural arrangements and morphological modifications were evidently ascertained. • Hybrid unveiled the small overpotentials and Tafel slopes for hydrogen evolution. • First-principle DFT calculations derived a low Gibbs energy of −0.01 eV for hybrid. We used a one-pot reaction to prepare mixed phase (2H-1T) molybdenum sulfide (MoS 2 ) and reduced graphene oxide (rGO) hybrids as electrocatalysts, which offer unique characteristics for hydrogen evolution reaction (HER) in acidic and alkaline solution. Mixed phase MoS 2 and rGO hybrid were characterized using related techniques. Nitrogen isotherm profiles confirmed the improved active surface area with mesoporous structure for 2H-1T MoS 2 /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 MoS 2 /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 MoS 2 /rGO electrocatalysts. Density functional theory (DFT) estimations identified density of states variations for 2H-1T MoS 2 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 MoS 2 /rGO hybrid.