Synergistic influence of GNP-tuned morphology in binary metal sulfide binder-free electrocatalysts for enhanced bifunctional water splitting

Abstract

Electrochemically breaking down water into hydrogen and oxygen presents a promising opportunity for sustainable energy production. However, developing electrocatalysts that are both cost-effective and efficient remains a significant challenge for advancing water electrolysis. Surface engineering of transition metal-based materials has emerged as a key strategy for creating stable, high-performance, non-noble metal electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Using a one-pot hydrothermal approach, we synthesized a novel GNPs@Ni₃S₂/MoS₂ (GNSMS) hybrid composite with a lateral heterostructure directly on Ni foam. This binder-free GNSMS catalyst exhibits excellent bifunctional electrocatalytic activity for both OER and HER in alkaline media. Electrochemical evaluations reveal that the catalyst performs more efficiently and exhibits greater stability due to the synergistic effects of its uniform, conformal architecture and enhanced charge and mass transfer properties. The GNSMS catalyst demonstrates low overpotentials of 87 mV for HER and 119 mV for OER at a current density of 10 mA cm⁻², indicating high intrinsic catalytic activity. Chronoamperometric studies further support the presence of faster reaction kinetics. Overall, this study highlights the GNSMS composite as an outstanding bifunctional electrocatalyst and provides valuable insights into the structure activity relationship, offering guidance for the future design of catalysts through multiscale engineering approaches.