Yolk-shell N/P/B ternary-doped biocarbon derived from yeast cells for enhanced oxygen reduction reaction

Developing cost-effective, sustainable and efficient electrocatalyst for the oxygen reduction reaction (ORR) is still a challenge for the practical application of fuel cells and metal-air batteries. The conversion of sustainable biomass into carbon provides a great opportunity to meet this challenge. In this work, without using any template, yolk-shell N/P/B ternary-doped biocarbon has been fabricated via a facile and low-cost biosynthesis method using yeast cells as precursor. The yolk-shell structure along with mesopores and micropores provides an efficient mass-transport pathway and increases the accessible active sites for the ORR. The doping of B increases the content of N doped in biocarbon, which favors the ORR. Significantly, the improved electrical conductivity and enhanced kinetics for charge transfer induced by co-doping of N, P and B with optimized content in carbon benefit the oxygen reduction kinetics. Thanks to these advantages, the as-prepared yolk-shell N/P/B ternary-doped biocarbon exhibits high electrocatalytic activity and good stability for ORR and high tolerance for methanol oxidation. A negative shift of about 56 mV in the onset potential and 79 mV in the half-wave potential of the biocarbon as compared to the commercial Pt/C (20 wt% Pt on Vulcan XC-72) for the ORR are achieved. (C) 2016 Elsevier Ltd. All rights reserved.