Highly stable linking platinum and porous spinel via carbon bridge engineering towards long-lifespan of rechargeable zinc-air battery

Abstract

The development of bifunctional oxygen electrocatalyst is crucial for the commercialization of rechargeable zinc-air batteries (RZABs). This work proposes an innovative strategy of "dealloying-carbon coating-dip pyrolysis" to highly stable anchor a small amount of Pt nanoparticles (0.032 mg cm -2 ) onto carbon-encapsulated nanoporous CoFe2O4 (np-CFO). Benefiting from its nanoporous structure with larger specific surface area and adhered carbon layer with superior electrical conductivity, the sandwich-like Pt/np-CFO@C electrode exhibits a lower OER-ORR potential gap (ΔE) of 0.7 V. Meanwhile, Pt/np-CFO@C based RZAB delivers specific capacity of 781 mA h g -1 , power density of 185 mW cm -2 and cycling life exceeding 1400 hours.FTIR and XAFS results indicate carbon layer could not only play a bridging role between np-CFO and Pt, but also lead to load more zero valence Pt. HAADF image proves that the post-formed oxide layer can protect Pt from inactivation through strong metal-support interaction (SMSI). In-situ Raman and RRDE testing confirm the 4-electron transfer mechanism of ORR on Pt/np-CFO@C. DFT calculations verify that Pt/CFO@C has metallic property, symmetric d-band centers and the lowest energy barrier for ORR/OER. In-situ XRD reveals that the size of Pt nanoparticles could get smaller in the early stage of discharge, which is beneficial to expose more active sites and show gradually improving performance. This work lays the groundwork for the future development of cost-effective RZABs.