A universal strategy for carbon–based ORR–active electrocatalyst: One porogen, two pore–creating mechanisms, three pore types

The universal strategy to synthesize efficient and cheap metal–free oxygen reduction reaction (ORR) catalysts is extremely urgent for the commercialization of fuel cells (FCs). This work luckily meets this by utilizing solo porogen ([ZnCO3]2∙[Zn(OH)2]3) to fabricate fluffy carbon with micro/meso/macropores from 15 kinds of daily biomass. The representative sample NMC–1 performs excellent four–electron ORR activity, delivers onset potential of 0.96 V, half–wave potential of 0.82 V, together with outstanding durability and poison resistance. The precursor can be extended to 15 kinds of biomass substantially confirms [ZnCO3]2∙[Zn(OH)2]3 as solo porogen is a vividly universal protocol to prepare hierarchical carbon as ORR catalysts from low–cost biomass, where the underlying formation mechanism may be based on the two-step decomposition of [ZnCO3]2∙[Zn(OH)2]3 involved in pyrolysis process. Such concise one–porogen method holds promising potential as general approach to synthesizing desirable ORR catalysts from widely available biomass. In addition, the ORR catalytic activity of as-prepared hierarchically porous carbon changes with the increase of the proportion of mesopore and macropore volume and the peak is obtained at 0.76. Therefore, the proportion of mesopore and macropore volume might be applied as one indicator to evaluate the ORR performance of metal-free carbon materials.