Atomic Sn sites supported on N-doped porous carbon for accelerating the oxygen reduction reaction

The oxygen reduction reaction (ORR) is the key half-reaction in various modern transduction devices. However, it is still hugely urgent to exploit high-efficiency and low-cost catalysts to overcome the problem of the slow dynamics for the ORR. Here, a catalyst with atomic Sn centers decorated into N-doped porous carbon, namely Sn-NC, was formulated by thermal decomposition of SnCl2 and laver in the presence of ZnCl2. Electron microscopy and X-ray absorption spectroscopy demonstrate the atomic distribution nature of Sn species in Sn-NC with a SnN4 coordination structure. Impressively, Sn-NC displays superior ORR activity in both acid and alkaline solutions with a half-wave potential of 0.98 V versus reversible hydrogen electrode (RHE) in 0.1 M KOH and 0.82 V versus RHE in 0.1 M HClO4 as well as good stability. More importantly, when employed as the cathodic active material of a Zn-air battery and fuel cell, Sn-NC shows a peak power density of 118 and 1290 mW cm-2, respectively, competitive to the commercial Pt/C catalyst. This work should be helpful for exploiting inexpensive ORR catalysts with promising potential for practical application. A catalyst with discrete atomic Sn sites decorated into N-doped porous carbon has been prepared, which displays superior ORR activity in both acid and alkaline solutions.