Biomass or bio-mess: tackling reproducibility in biomass-derived carbon electrocatalysts†

The pyrolysis of biomass is a promising route toward carbon electrodes, but its adoption in electrocatalysis is mostly limited to the oxygen reduction reaction. To prepare precise active sites for other electrocatalytic reactions in the oxygen, nitrogen, and carbon cycles, the complexity of both the biomass precursor and the pyrolysis process must be reigned in. We now report a two-stage strategy for stabilizing the synthesis of a reproducible electrocatalyst for a reaction requiring a precise active site, namely the hydrazine oxidation reaction. The strategy starts with a common yet variable biomass (ground coffee waste) and proceeds through (1) optimized activation by a range of methods, and (2) scalable introduction of Fe–N₄ centers. The result is a sustainable, highly active, and most importantly, reproducible, Fe–N–C electrocatalyst. This work should help the scientific and technological communities to realize the full potential of biomass as a source for carbon electrodes.