Prussian blue analogue Cu3[Fe(CN)6]2 derived N-doped Cu/Fe3C clusters as an excellent non-noble metal ORR catalyst for microbial fuel cells

Abstract An excellent non-noble metal ORR catalyst is fabricated using prussian blue analogue (Cu3[Fe(CN)6]2) and melamine via a simple process. Cu3[Fe(CN)6]2 serve as both the template for the pore formation and the precursor for the ORR active sites. Melamine has the following advantages: melamine contains higher content of nitrogen for the preparation of pyridinic-N, graphitic-N, and pyrrolic-N to improve the ORR performance; in addition, during pyrolysis, carbon nitrogen species decomposed from melamine at higher temperature can subsequently bind with metal atoms to form M-Nx moieties, preventing metal atoms from aggregation. In this novel catalyst (Cu/Fe/N-C), nitrogen-coordinated Cu and Fe3C clusters (about 3 nm) are homogeneously dispersed on the surface of the carbon substrate. Owing to the synergic effect of its unique multi-interface hetero structure, rapid ion transport in its porous structure and plenty of high nitrogen-coordinated Cu/Fe clusters catalytic active sites, Cu/Fe/N-C displayed excellent ORR performances, with much more positive on-set potential (0.12 V vs Ag/AgCl) and half-wave potential (0.00 V vs Ag/AgCl). When used in air-cathode MFCs, the maximum output voltage and power density of Cu/Fe/N-C were slight less than those of the commercial 20% Pt/C, but the stability and methanol tolerance were superior. Significantly, the cost of Cu/Fe/N-C was lower than Pt/C and the method of synthesizing catalyst was facile. Thus, this novel catalyst was a promising alternative ORR replacing Pt/C catalyst used in future industrial application. This strategy, combing prussian blue analogue with melamine to fabrication clusters catalyst, exhibits a promising prospect for broadening the development ORR catalysts in energy.