Theoretically Revealed and Experimentally Demonstrated Synergistic Electronic Interaction of CoFe Dual-Metal Sites on N-doped Carbon for Boosting Both Oxygen Reduction and Evolution Reactions

Heteronuclear double-atom catalysts, unlike singleatom catalysts, may change the charge density of active metal sites byintroducing another metal single atom, thereby modifying theadsorption energies of reaction intermediates and increasing thecatalytic activities. First, density functional theory calculations areused tofigure out the best combination by modeling two transition-metal atoms from Fe, Co, and Ni onto N-doped graphene. Generally,Fe and Co sites are highly active for the oxygen reduction reaction(ORR) and the oxygen evolution reaction (OER), respectively. Thecombination of Co and Fe to form CoFe-N-C not only furtherimproves the Fe's ORR and Co's OER activities but also greatlyenhances the Co site's ORR and Fe site's OER activities. Then, wesynthesize the CoFe-N-C by a two-step pyrolysis process andfindthat the CoFe-N-C exhibits exceptional ORR and OER electro-catalytic activities in alkaline media, significantly superior to Fe-N-C and Co-N-C and even commercial catalysts.

Automated summary

Heteronuclear double-atom catalysts modify the charge density of active metal sites and enhance catalytic activities. CoFe-N-C exhibits exceptional ORR and OER electro-catalytic activities in alkaline media.