Designing of highly-efficient oxygen evolution reaction electrocatalyst FeCo-hydroxyl phosphates: Theory and experiment

• The correlation factor of d electron density is adopted for the Co-introduction in transition metal hydroxyl phosphate; • The foreign Co atom increases the d electron density and improves the catalytic activity of Fe ion; • The prepared FeCoPO 4 specimen exhibits low η exp of 241 mV. The development of a physical factor to correlate the experimental methods and catalytic activity of catalysts is quite important for the design of highly-efficient catalysts. In this work, with the aid of our pre-designed correlation factor of d electron density, a new oxygen evolution reaction electrocatalyst of FeCoPO 4 was designed on account of the higher electronegativity of Co atom than Fe atom. The foreign Co atom would enhance the combining capacities of the neighbouring Fe-O bonds, increase the d electron density and reduce the chemical activity of host Fe ions, and thus improve the catalytic activity of Fe based active centers. Based on the theoretical guidance, the prepared FeCoPO 4 specimen exhibited low η exp of 241 mV, fast charge transfer rate, high intrinsic activity and stable electrocatalytic activity. This strategy would be adopted to design highly-efficient catalyst by altering the d electron density of transition metal ions with suitable preparation methods.