Rational Regulation of Crystalline/Amorphous Microprisms-Nanochannels Based on Molecular Sieve (VSB-5) for Electrochemical Overall Water Splitting

Rational regulation of the composition and structure of electrocatalysts is crucial to the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Herein, a new electrocatalyst of nickel phosphate microprism (VSB/NiPO) is developed via a simple solvothermal reaction. The microprism is mainly composed of Versailles-Santa Barbara-5 (VSB-5, molecular sieve) with unique nanochannels, which contribute to accelerating mass transfer and exposing more active sites, thus displaying excellent HER activity. Subsequently, the crystallinity and electronic structure of the framework are modulated by incorporating Fe with the combination of calcination and impregnation. The nanochannels are converted to the amorphous arrangement, and the Ni centers are regulated to the higher valence. The resultant Fe-VSB/NiPO-500 exhibits a low OER overpotential of 227 mV at 50 mA cm(-2). Interestingly, an integrated electrolyzer assembled by VSB/NiPO(-) and Fe-VSB/NiPO-500(+) performs well for overall water splitting, which requires only 1.487 V to achieve 10 mA cm(-2), and remains stable at 100 mA cm(-2) over 100 h. This finding opens a new avenue for developing VSB-5 in the field of electrocatalysis.

Automated summary

Rationally regulating the composition and structure of electrocatalysts is crucial in HER and OER. A new electrocatalyst of nickel phosphate microprism (VSB/NiPO) is developed with excellent HER activity. Modulating the crystallinity and electronic structure of the framework further improves the performance. The assembled electrolyzer achieves efficient and stable water splitting under low energy consumption.