Porous biochar aerogel loaded PtFe alloys derived from natural marine polysaccharide for efficient oxygen reduction

Abstract

Lowering the Pt loading of Pt-based materials is a promising strategy to explore excellent oxygen reduction reaction (ORR) electrocatalysts. One surprising approach is to develop Pt-alloys, which can effectively reduce the usage of Pt and induced highly catalytic activity through regulation effect between multimetals. Herein, the N-doped porous biochar aerogel/reduced graphene oxide loaded PtFe alloys (PtFe/NC-rGO (Pt1Fe5)) with low Pt loading (with a Pt content of 7.54 wt%) were prepared using natural marine polysaccharide-alginate as precursor through simple pyrolysis process. The biochar aerogel as an ideal carbon support shows an excellent electrical conductivity as well as a high specific surface area utilized for mass transport together with ion diffusion during ORR. Consequently, the PtFe/NC-rGO (Pt1Fe5) exhibits highly excellent ORR catalytic activity with respect to the pure Pt/NC-rGO together with the commercial Pt/C catalysts, with good half-wave potentials of 0.81 and 0.87 V vs. RHE in 0.5 M H2SO4 as well as 0.1 M KOH solutions, respectively. The strategy gives a new way to construct Pt-based alloy ORR electrocatalysts with low Pt consumption and the easy availability of biomass raw materials for PtFe/NC-rGO ensures its potential for large-scale application.