Single-atom Pt supported on holey ultrathin g-C3N4 nanosheets as efficient catalyst for Li-O2 batteries.

As for electrocatalysis, single-atom metal catalysts have been proved to lower the cost and utilize precious metals more efficiently. Herein, single-atom Pt catalyst supported on holey ultrathin g-C3N4 nanosheets (Pt-CNHS) was synthesized via a facile liquid-phase reaction of g-C3N4 and H2PtCl6. The single-atom Pt can achieve high dispersibility and stability, which can promote the utilization efficiency as well as enhance the electrochemical activity. When employed as Li-O2 batteries' cathode catalyst, Pt-CNHS exhibits excellent electrocatalytic activity. Li-O2 batteries utilizing Pt-CNHS show much higher discharge specific capacities than those with pure CNHS. Li-O2 batteries with Pt-CNHS cathode can be cycled stably for 100 times under the discharge capacity of 600 mAh g-1. Based on experimental results and density functional theory calculations, the superior electrocatalytic activity of Pt-CNHS can be ascribed to the large surface area, the enhanced electrical conductivity and the efficient interfacial mass transfer through Pt atoms and porous structure of CNHS.