Constructing atomic single metal Co-C₃(OH)₁ sites with graphdiyne for zinc-air batteries

Single-atom metal-N_x sites have exhibited excellent catalytic properties and garnered growing attention. Typically, these metal atoms rely heavily on N atoms to anchor them to the carbon substrate. However, since N atoms are generally doped by post-treatments, the content of N is low. Thus, it is limited in constructing diverse efficient single-atom active sites. Herein, we employ hydrogen-substituted graphdiyne (HsGDY) as a carbon substrate to construct a cobalt atom electrocatalyst (Co-HsGDY) for the oxygen reduction reaction (ORR). Thanks to the special sp-C in HsGDY, Co atoms can be anchored to the carbon support without the help of N. Besides, benefitting from the elegant molecular pores of HsGDY, there is enough space for the metal atoms to coordinate with oxygen-containing groups, which further modulates the electronic structure of the central metal. The Co-HsGDY exhibits an ORR catalytic activity comparable to that of Pt/C. Moreover, the Co-HsGDY based rechargeable zinc-air battery displays an outstanding performance with a power density as high as 209.5 mW cm⁻² and superior long-term stability.