Improved performances toward electrochemical carbon dioxide and oxygen reductions by iron-doped stannum nanoparticles.

The CO2 reduction reaction (CO2RR) and oxygen reduction reaction (ORR) show great promise for expanding the use of renewable energy sources and fostering carbon neutrality. Sn-based catalysts show CO2RR activity; however, they have been rarely reported in the ORR. Herein, we prepared a nitrogen-carbon structure loaded with Fe-doped Sn nanoparticles (Fe-Sn/NC), which has good ORR and CO2RR activity. The results reveal that the Fe-Sn/NC catalysts deliver a high FECO of 99.0% at a low overpotential of -0.47 V in an H-type cell for over 100 h. Notably, a peak power density of 1.36 mW cm-2 is achieved in the Zn-CO2 battery with the Fe-Sn/NC cathode at discharge current densities varying from 2.0 to 4.0 mA cm-2, and the FECO remains above 99.0%. Due to efficient oxygen reduction reaction (ORR) performance and Zn-air battery (ZAB) characteristics, the ZAB-driven CO2RR has strong catalytic stability. This work proves that Fe-Sn/NC enhances the performance of the CO2RR and ORR, and the study of Zn-based batteries provides a new research direction for energy conversion.