Hierarchically porous carbon microspheres with fully open and interconnected super-macropores for air cathodes of Zn-Air batteries

Hierarchically porous materials have drawn extensive attention to construct effective air cathodes in newly developed zinc-air batteries. Here, we successfully fabricated hierarchically porous carbon microspheres (HCMs) with fully open and interconnected super-macropores by a strategy of high internal phase W/O/W double emulsions (HIPDEs). The as-prepared HCMs-supported platinum nanoparticles (Pt/HCMs) were employed as novel ORR catalysts for the air cathodes of Zn-air batteries. It was found that Pt/HCMs promised a nearly 100% Pt utilization and showed a higher current density and better durability than the commercial Pt/C on rotating disk electrode (RDE) setup and gas diffusion electrode (GDE)-based half-cell configurations, highlighting the importance of the fully open and interconnected super-macropores for improving the gas/liquid phases transport. Benefiting from the superior mass transfer, the Pt/HCMs-based Zn-air battery delivered high power density (190 mW cm−2) and specific capacity (800 mA h gZn−1) comparable to that of the commercial Pt/C-based battery. This study presents a new avenue to engineer catalyst to boost the performance of Zn-air batteries.