In situ reconstructed Fe-Ni3 S2 /VSB-5 composite based on molecular sieve (VSB-5) for efficient oxygen evolution reaction

The oxygen evolution reaction (OER) is a multi-electron reaction compared to the hydrogen evolution reaction (HER), which severely limits the efficiency of water electrolysis. Therefore, the exploration of highly active, costeffective, and stable catalysts is significant for the development of water electrolysis. Herein, a composite catalyst Fe-Ni3S2/VSB-5 was successfully fabricated by sulfurization and concomitant in-situ reconstruction of VSB-5. FeNi3S2/VSB-5 exhibits a unique composite morphology consisting of microprisms with the multi-step-like surface of VSB-5 and the brushwood-like morphology of Fe-Ni3S2. The sulfurization process leads to the in-situ reconstruction of VSB-5. The original hexagonal prismatic morphology of VSB-5 changes into the prisms with multistepped surfaces. The reconstructed VSB-5 exhibits the increased pore disorder and exposes a large number of stepped crystal planes, which is beneficial for the exposure of active sites and the contact between the catalyst and the electrolyte, while maintaining the superhydrophilicity of the original VSB-5. Thus, the composite catalyst Fe-Ni3S2/VSB-5 demonstrates outstanding OER performance in 1.0 M KOH, only requiring 193 and 256 mV overpotentials to achieve 10 and 100 mA cm-2, respectively. More importantly, Fe-Ni3S2/VSB-5 exhibits excellent stability at 100 mA cm-2 for at least 180 hours.