P-Block Atomically Dispersed Antimony Catalyst for Highly Efficient Oxygen Reduction Reaction.

Main-group ( s - and p -block) metals are generally regarded as catalytically inactive due to the delocalized s / p -band. Herein, we successfully synthesized a p -block antimony single-atom catalyst (Sb SAC) with the Sb-N 4 configuration for efficient catalysis of the oxygen reduction reaction (ORR). The resulting Sb SAC exhibits superior ORR activity with a half-wave potential of 0.86 V and excellent stability, which outperforms many transition-metal (TM, d -block) based SACs and commercial Pt/C. In addition, it presents an excellent power density of 184.6 mW cm -2 and a high specific capacity (803.5 mAh g -1 ) in Zn-air battery. Both experiment and theoretical calculation manifest that the active catalytic sites are positively charged Sb-N 4 single-metal sites, which have closed d shells. Density of states (DOS) results unveil the p orbital of the atomically dispersed Sb cation in Sb SAC can easily interact with O 2 - p orbital to form hybrid states, facilitating the charge transfer and generating appropriate adsorption strength for oxygen intermediates, lowering the energy barrier and modulating the rate-determining step. This work sheds light on the atomic-level preparing p -block Sb metal catalyst for highly active ORR, and further provides valuable guidelines for the rational design of other main-group-metal SACs.