A novel transition metal dichalcogenide – reduced graphene oxide electrocatalyst family for hydrogen evolution reaction

Abstract

The global energy crisis underscores the critical need for sustainable hydrogen production via efficient electrocatalysts. This study presents a novel family of transition metal dichalcogenide-reduced graphene oxide (MoS2-rGO) hybrids and doped variants (V, W, Co) for the hydrogen evolution reaction (HER). Using orthogonal experimental design (L9(33)), we optimized synthesis parameters (rGO content, heating temperature, duration) to develop a MoS2-rGO composite with 0.8 wt% rGO, synthesized at 200°C for 24 h. This optimized catalyst achieved superior HER performance in acidic media (0.5 M H2SO4), exhibiting a low overpotential (η10 = -0.34 Vs RHE) and Tafel slope (98.2 mV/dec), significantly outperforming undoped MoS2 (η10 > 0.40 Vs RHE, Tafel slope 113.0 mV/dec). While Pt/C remains the benchmark catalyst with ultra-low overpotential (~0.05 V vs. RHE) and a Tafel slope of ~30 mV/dec, its high cost and scarcity hinder widespread application. In contrast, our MoS2-rGO catalysts offer a noble-metal-free alternative with enhanced conductivity and stability, facilitated by rGO integration. XRD and Raman spectroscopy confirmed structural improvements, while vanadium doping increased active site exposure, tungsten doping introduced sulfur vacancies to optimize hydrogen adsorption energy, and cobalt doping altered electronic structures. Systematic characterization via XRD, XPS, BET, UV-vis, Raman spectroscopy, SEM and electrochemical techniques elucidated the structural and electronic contributions of each component. The synergistic effects of rGO and dopants were highlighted, with the Co0.05W0.05S2/rGO heterostructure showing promising HER activity. This work establishes a rational framework for designing noble-metal-free HER catalysts, emphasizing the interplay between defect engineering, interfacial interactions, and scalable synthesis strategies. The integration of orthogonal optimization with multi-technique characterization provides a robust pathway for advancing green hydrogen technologies.