P-doped binary Ni/Fe–N–C for enhanced oxygen electrocatalysis performance

Abstract

Adjusting the micro-environment of highly dispersive metals on carbon supports has been proved to be effective for achieving enhanced electrocatalysis performance. Herein, we delicately design a phosphorus-doped binary NiFe–nitrogen–carbon material (denoted as P-NiFe–NC), taking advantage of the coupling reaction between phenylphosphonamide (P dopant) and formamide (the carbon and nitrogen sources). The XPS N 1s fine scan reveals the strong interplay of N and P by the positively shifted binding energy of pyridinic N species after P incorporation, and the chemical state of Fe species is influenced accordingly. In addition, the P doping can enlarge the specific surface area and increase the meso/macroporosity of NiFe–NC, thus contributing to the enhancement of mass transfer inside the pores. The P-NiFe–NC sample exhibits favorable bifunctional oxygen electrocatalysis performance, rendering an ORR half-wave potential of 0.85 V and an OER potential of 1.69 V@10.0 mA cm⁻², superior to those of P-free NiFe–NC. Assembled into Zn–air batteries, P-NiFe–NC delivers a high specific power of 161.36 mW cm⁻² and stable charge/discharge for over 100 h (corresponding to 300 cycles).