Carbon skeleton dispersed nano-jarosite for efficient Cr (VI) degradation: A bioinspired MFC cathode catalyst

Relevant advancements in microbial fuel cells (MFCs) are impeded by the limited oxygen reduction reactions at the cathode. The challenge prompted the development of a jarosite-biochar catalyst using a straightforward biomineralization method. Through X-ray diffraction (XRD) and scanning electron microscope (SEM) analysis, we observed a reduction in the agglomeration phenomenon of nano jarosite and a decrease in particle size. The biochar-jarosite MFC demonstrated a significant increase in voltage (682.5 mV) and a maximum power density of 1211 mW/m2. Electrochemical impedance spectroscopy (EIS) showed that the charge transfer resistance of the cathode decreased from 2580 omega to 111 omega, demonstrating excellent oxygen reduction reaction (ORR) performance. The jarosite-biochar significantly enhanced the MFC degradation of Cr (VI), exhibiting a 5.2-fold increase, while demonstrating exceptional stability. The X-ray photoelectron spectroscopy (XPS) of Fe and Cr on the surface of jarosite-biochar further substantiates the role of jarosite as an electron mediator between biochar and Cr (VI) in the MFC. Our study presents a cost-effective and efficient biomineralization strategy for the modification of cathode materials in MFCs, offering significant potential for enhancing the catalytic performance of iron-containing carbonaceous composites in Cr (VI) environments.