Abstract: Biochar nano-sheets (BXG-AC) with high surface area and porous structure were prepared by direct pyrolysis of the inner membrane of passion fruit and subsequent KOH activation. The morphology and surface elemental composition of BXG-AC were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) and the electrochemical behaviors were investigated by cyclic voltammetry and linear sweep voltammograms (LSV). The results indicate that in neutral media, the as-prepared BXG-AC catalyst exhibits remarkable electrocatalytical activity; a maximum power density of 1153.3 mW/m² is achieved in the microbial fuel cells (MFCs), which is comparable to that of commercial Pt/C (1214.3 mW/m²). Furthermore, the BXG-AC cathode also displays a great long-term stability; the MFC output decreases slightly after operation for more than 60 cycles. This study demonstrates that the biochar nano-sheets derived from the inner membrane of passion fruit is probably a cost-efficient and promising cathodic catalyst for the scale-up MFCs.