ZIF template-based Fe-doped defect-rich hierarchical structure Co3S4/MoS2 as a bifunctional electrocatalyst for overall water splitting

To replace the current expensive precious metal catalysts for water electrolysis, it is important to develop inexpensive and powerful bifunctional catalysts for hydrogen production. It is an effective way to improve catalytic performance using excellent templates and elemental doping. Here, a hierarchical structure Fe-Co₃S₄/MoS₂ was synthesized using an Fe-ZIF precursor prepared by ion exchange, followed by hydrothermal sulfuration and annealing. It required overpotentials of only 93 mV and 243 mV to achieve a current density of 10 mA cm^-2 in the HER and OER, respectively. It also showed excellent catalytic performance for overall water splitting, requiring only 1.42 and 1.71 V to achieve current densities of 10 and 100 mA cm^-2 in 1 M KOH. The catalyst also demonstrated excellent ultra-long-term stability. The superb catalytic performance and stability can be attributed to the Fe doping, exposing more active sites while retaining the highly stable framework of the ZIF. The component modulation of Co₃S₄ and MoS₂ by Fe doping induced high intrinsic activity and excellent transfer coefficients. This work presents a novel approach to prepare noble metal-free catalysts with highly stable rich interfaces and defects for overall water splitting.