Strategic design of NiS2/Co3S4 heterojunction for enhanced electrocatalytic hydrogen evolution in acidic media

The construction of heterogeneous interface significantly contributes to the boosted electrocatalytic activity for hydrogen evolution reaction (HER). This enhancement is achieved through the modulation of the electronic structure, facilitation of electron redistribution, and optimization of the electrocatalyst's chemisorption towards the reaction intermediates. Herein, NiS2/Co3S4 heterojunction was synthesized using a straightforward one-pot hydrothermal method, and the impact of heterogeneous interface on the electrocatalytic HER performances was investigated. The heterogeneous interface and strengthened interfacial effects between NiS2 and Co3S4 were confirmed by HRTEM and XPS. The NiS2/Co3S4 heterojunction demonstrate significantly enhanced HER performance in acidic solutions, owing to their clever structural design and the robust interfacial coupling effects within the heterogeneous interface structure, surpassing that of single-component NiS2 materials. The optimum NiS2/Co3S4 heterojunction presents a low overpotential of 253 mV and a Tafel slope of 62.0 mV dec−1 at 10 mA cm−2 toward HER. Density functional theory (DFT) calculation indicates that NiS2/Co3S4 heterostructure exhibit lower ΔGH* values compared to NiS2 and Co3S4. This suggests that the creation of heterogeneous interface can significantly optimize the adsorption capacity for hydrogen intermediates, thereby enhancing the HER in acidic media.