Coordination engineering and electronic structure modulation of FeNi dual-single-atoms encapsulated in N, P-codoped 3D hierarchically porous carbon electrocatalysts for synergistically boosting oxygen reduction reaction

With the increasing energy and environmental issues in recent years, it is vital to explore inexpensive and highly activated oxidation reduction reaction (ORR) catalysts for next generation energy storage and conversion devices such as zinc-air batteries. Herein, FeNi dual-single-atoms were efficiently encapsulated into N,P-codoped 3D hierarchically porous carbon electrocatalyst (FeNi DSAs/N,P-PC) by a simple one-step pyrolysis. The resulting FeNi DSAs/N,P-PC catalyst exhibited the better ORR activity with the positive onset potential (Eonset = 1.02V) and half-wave potential (E1/2 = 0.88V) over commercial Pt/C, and performed well in the assembled zinc-air batteries (peak power density of 124.73mWcm-2,and long-term charge/discharge stable cycling for 330hours).The XAFS analysis clearly displayed the coordination structure and interactions of FeNi dual atoms. The DFT calculations show that P-O bonds have greatly affected the electronic structure microenvironment of FeNi dual atoms. And Ni site can effectively modulate the electronic structure of the Fe site to promote charge transfer and further reduce the energy barrier of the rate-limiting step. This strategy provides a viable strategy for development of low-cost high-performance transition metal diatomic catalysts suitable for energy conversion and storage devices.