Pairing bimetallic metal-organic framework and phosphate derivative for alkaline overall water splitting

Abstract

The metal-organic frameworks (MOFs)/derivates emerged as promising catalysts for hydrogen generation from electrolyzing water, however, further improvements in the activities are still awaited. Herein, bimetallic MOFs and the derivates were developed for catalyzing the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) by regulating the morphology, and activity of the intermediates. We demonstrated the activity and morphology of the catalysts strongly correlated with the atomic ratio of Ni and Co in bimetallic MOFs. The hierarchical Ni0.1Co0.9-MOF delivered a relatively low overpotential of 384 mV to afford 100 mA/cm2 for OER, but a high overpotential of 512 mV for HER. While the phosphide Ni0.1Co0.9P only needed an overpotential of 276 mV to deliver 100 mA/cm2 for HER. And we discussed the roles of bimetallic sites and phosphorous in OER and HER in depth. More importantly the Ni0.1Co0.9-MOF and Ni0.1Co0.9P were integrated to drive the overall water splitting, at a current density of 10 mA/cm2, the overpotential value is 500 mV. This work provided insights into the exploration of efficient MOFs/derivates catalysts and shed new light on the novel combination for water electrolysis.