Embedded Platinum–Cobalt Nanoalloys in Biomass-Derived Laser-Induced Graphene as Stable, Air-Breathing Cathodes for Zinc–Air Batteries

Abstract

Fuel cells and metal–air batteries hold significant promise to help decarbonize transportation and the electricity grid. To encourage widespread adoption of these technologies, improvements to their air-breathing cathodes are required, which address problems such as the high cost of platinum (Pt) catalysts used to boost the kinetics of the oxygen reduction reaction (ORR) as well as the stability of Pt/C interfaces over long-term cycling. In this paper, we demonstrate a facile approach to reduce Pt content to less than 2 wt % by interfacing Pt with CoOx as well-dispersed nanoparticles entrapped within a highly conductive laser-induced graphene (LIG) matrix. Laser-induced carbonization of polymerized furfural alcohol preloaded with Co and Pt precursors resulted in the formation of a mixture of spherical nanoalloys PtCoOx and core (CoOx)–shell (Pt) structures. This LIG-PtCoOx electrode exhibited a low onset and half-wave potential in alkaline media, which closely approached a benchmark Pt/C. The effectiveness of LIG-PtCoOx was demonstrated by its performance in rotating disk and rotating ring disk electrode studies versus commercial Pt/C with the same concentration of the catalyst, which resulted in 4-fold greater mass activity and more than 6-fold higher specific activity, which are reflected in a high turnover frequency (TOF). The resulting material was tested as an air–cathode for zinc (Zn)–air batteries leading to improved stability (118 h of operation) and rechargeability (0.75 V voltage gap), exhibiting a higher peak power density compared to batteries assembled with the commercial benchmark Pt/C cathodes with similar composition.