The activation of inert NiFe Prussian Blue analogues to boost oxygen evolution reaction activity

The inert sites of Prussian Blue Analogue (PBA) seriously affected its electrocatalytic activity and application, how to activate inert sites in PBA to fulfill effective oxygen evolution reduction (OER) is a major challenge. Herein, Mo substituted Fe sites and S doped in inert PBA were designed and synthesized by hydrothermal method to enhance structural stability and OER activity. PBA-SMo/NF shows the optimum activity with a low overpotential of 252 and 294 mV for harvesting current density 20 and 100 mA cm^-2, respectively, and exhibits excellent durability under high current density. Theoretical calculation of H₂O adsorption energy and Bader charges reveals that Mo sites in PBA-SMo possess favourable H₂O adsorption kinetics. More important, Gibbs free energy diagram and DOS show PBA-SMo have lower energy barriers for OER and better conductivity. This work provides a kind of guidance for the design and optimization of PBA for broad applications.