Hierarchically Porous and Defective Carbon Fiber Cathode for Efficient Zn-Air Batteries and Microbial Fuel Cells

Developing low-cost, efficient oxygen reduction reaction (ORR) catalysts to replace Pt-based materials is urgently required for the application of Zn-air batteries (ZABs) and microbial fuel cells (MFCs). In this work, meso-microporous carbon fibers with tunable defect density were synthesized by carrageenan fibers. A highly defective carbon fiber (HDCFs) was produced which exhibited an outstanding ORR catalytic activity, reaching to the half-wave potential of 0.841 and 0.44 V in alkaline and neutral electrolytes, respectively. These HDCFs can also act as highly efficient air cathodes for ZABs (delivered potential of 0.69 V and power density of 220 mW cm(-2) at 300 mA cm(-2)) and MFCs (high power density of 69.7 mW cm(-2)). Simulation by the density functional theory indicated that a high density of defections in a carbon based framework can remarkably modulate the electrical properties. For instance the charge entrapments in the carbon active sites may reduce the energy barrier of ORR.

Automated summary

This study developed meso-microporous carbon fibers with tunable defect density and found that they exhibited outstanding ORR catalytic activity, which can serve as highly efficient catalysts for ZABs and MFCs.