Silver based single atom catalyst with heteroatom coordination environment as high performance oxygen reduction reaction catalyst

Ag is a potential low-cost oxygen reduction reaction (ORR) catalyst in alkaline condition, which is important for the zinc-air batteries. Here, we report that an Ag based single atom catalyst with heteroatom coordination. Ag₁-h-NPClSC, has been synthesized and shown much improved performance towards ORR by manipulating the coordination environment of the Ag center. It shows a high half wave potential (0.896 V) and a high turnover frequency (TOF) (5.9 s⁻¹) at 0.85 V, which are higher than the previously reported Ag based catalysts and commercial Pt/C. A zinc-air battery with high peak power density of 270 mW·cm⁻² is fabricated by using the Ag₁-h-NPClSC as air electrode. The high performance is attributed to (1) the hollow structure providing good mass transfer; (2) the single atom metal center structure providing high utility of the Ag; (3) heteroatom coordination environment providing the adjusted binding to the ORR intermediates. Density functional theory (DFT) calculations show that the energy barrier for the formation of OOH*, which is considered as the rate determine step for ORR on Ag nanoparticles, is lowered on Ag₁-h-NPClSC, thus improving the ORR activity. This work demonstrates that the well manipulated Ag based single atom catalysts are promising in electrocatalysis.