Systematic Mapping of Electrocatalytic Descriptors for Hybrid and Non-Hybrid Molybdenum Dichalcogenides with Graphene Support for Cathodic Hydrogen Generation

Abstract

For the hydrogen evolution reaction (HER) from water electrolysis, electrocatalytic performances of nanocomposites consisting of hybrid and non-hybrid molybdenum dichalcogenides with graphene (MoCh2/Gr) support (MoS2/Gr, MoSe2/Gr, MoTe2/Gr, MoSSe/Gr, MoSTe/Gr, MoSeTe/Gr, and MoS0.67Se0.67Te0.67/Gr) have been investigated both computationally and experimentally. In the computational part, hydrogen binding energetics of various adsorption sites on hybrid and non-hybrid MoCh2/Gr are elucidated with plane-wave density functional theory to evaluate the catalytic performance according to Sabatier’s principle. Near-zero values of Gibbs free energy of binding (ΔGb ≈ 0) have been considered a criterion for establishing the most catalytically active site. Moreover, electrochemical measurements revealed that all the materials, which have been synthesized through a microwave-assisted heating approach, are highly active and durable for the HER with overpotentials in the range of 127–217 mV and have negligible activity loss for 96 h of constant potential tests. Among all the different molybdenum dichalcogenide/graphene nanocomposites, the materials containing a high (≥50%) stoichiometric proportion of tellurium (Te) exhibited better HER activities compared to other chalcogens. Most importantly, hybrid nanocomposites, except the highest-entropy alloy MoS0.67Se0.67Te0.67/Gr, exhibited improved performance compared to the non-hybrid MoCh2 compounds.