Bamboo charcoal as a cost-effective catalyst for an air-cathode of microbial fuel cells

In this study, bamboo charcoals (BCs) obtained by carbonizing bamboo branches (Phyllostachys pubescens Mazel) in a N2 atmosphere were used as high-performance, cost-effective catalysts for the oxygen reduction reaction (ORR) in microbial fuel cells (MFCs). The obtained catalyst (BC-HT) showed a maximum power density (Pmax) of 1056 ± 38 mW m−2, which was comparable to that of the commercial Pt/C catalyst (1039 ± 15 mW m−2). Additional N and P doping by soaking the carbonized BC in a (NH4)3PO4 solution (BC-HT-NP-HT) resulted in a 65% higher Pmax (1719 ± 82 mW m−2) compared to that of Pt/C. This improvement can be attributed to not only the high electrical conductivity, the sufficient amount of N- and P-containing groups, and the presence of many effective active sites (i.e., pyridinic-N, graphitic-N, P-N and P-O-CO3) but also the high tolerance of BC-HT-NP-HT to the poisoning species under the relevant MFC conditions. These results demonstrated that easily available BCs can be cost-efficient and high-performing catalysts for ORR in air-cathode MFCs.