Metal-free catalyst for efficient pH-universal oxygen reduction electrocatalysis in microbial fuel cell

Developing and utilization of clean and renewable energy is the key to alleviate energy crisis and environmental problems. As a biomass energy utilization, microbial fuel cell (MFC) suffers from low power generation performance caused by the sluggish electronic transfer kinetics of cathodic oxygen reduction reaction (ORR). It is of significance to develop efficient ORR catalysts to get a commercial-scale version in fuel cells. ZIF-8 was usually joined other metal elements (Pt, Fe, Co and etc) to improve ORR catalytic ability. Unfortunately, these catalysts are unstable under acidic conditions. Therefore, it is of great significance to develop an efficient pH universal ORR catalyst. Herein, a kind of metal-free and efficient pH-universal ORR catalyst are fabricated via a simple method. The catalyst (ZIF-8#1000) exhibits excellent pH-universal ORR electrocatalytic activity and high-performance in single-chamber MFC (distinct output voltage 780 mV and maximum power density 600 mW m(-2)), comparable to those of 20% Pt/C. Interestingly, three single-chamber MFCs in series can light a light-emitting diode. Thus, the as-prepared ZIF-8#1000 has the potential to be alternative of Pt-based ORR catalysts.

Automated summary

Developing and utilizing clean and renewable energy is crucial in addressing energy crisis and environmental issues. Microbial fuel cells (MFCs), as a type of biomass energy utilization, suffer from low power generation efficiency due to slow electronic transfer kinetics. It is important to develop efficient oxygen reduction reaction (ORR) catalysts to improve the performance of fuel cells. However, current catalysts are unstable under acidic conditions. Therefore, the development of a pH universal ORR catalyst is of great significance. In this study, a metal-free and efficient pH universal ORR catalyst was fabricated and demonstrated excellent performance in experiments.