Lateral synergy of SbN4 and FeN4OH dual sites for boosting oxygen reduction in PEMFC and ultralow temperature Zn-air battery

Dual atom catalysts (DAC) have attracted extensive concerns due to the combinatorial diversity of two central sites and their synergistic effects for boosting oxygen reduction reaction (ORR). However, how the synergistic effect modulates the local electronic structure and thus enhances the ORR activity is still ambiguity. Here, we successfully synthesize FeSb-NC diatomic catalysts with a new local structure of FeN4OH-SbN4, which is identified by synchrotron X-ray adsorption fine spectroscopy. The FeSb-NC shows excellent ORR activity with half-wave potentials of 0.795 V in 0.1 M HClO4 and 0.905 V in 0.1 M KOH. Importantly, the FeSb-NC-based proton exchange membrane fuel cell exhibits a peak power density (PPD) of 0.4 W cm−2 at 1 bar H2/air condition, and the current density at 0.6 ViR-free reaches 0.673 A cm−2. Furthermore, the FeSb-NC-based solid-state Zn-air battery exhibits an ultrahigh PPD of 57.5 mW cm−2 at −40 °C ultralow temperature, apparently superior to Fe-NC and Pt/C – based ones. DFT calculations further reveal the synergistic catalytic mechanism of SbN4 and FeN4OH species, i.e. SbN4 could act as a lateral coordination site to enhance reaction kinetics and adsorption ability of FeN4OH species, and thus significantly boosts ORR performance. This work provides a new route of lateral coordination for the design of diatomic catalysts.