Template-free synthesis of biomass-derived hierarchically mesoporous carbon with ultra-small FeNi nanoparticles for oxygen evolution reaction

Highly active and stable catalysts towards electrochemical oxygen evolution reaction are crucial for efficient water splitting and sustainable hydrogen generation. Here we report a carbon supported FeNi catalyst synthesized from an in situ freeze-drying method (fd-FeNi/C) with a commonly seen biomass, jasminum mesnyi flower. The fd-FeNi/C exhibits a N-doped hierarchically mesoporous carbon structure decorated with small FeNi nanoparticles with a small diameter of ∼ 4 nm. Electrochemical measurements show excellent catalytic performance in 1 M KOH solution with an overpotential of 301 mV at the current density of 10 mA cm−2. The value is 41 mV lower than that of the commercial IrO2/C. A small Tafel slope (64.5 mV dec−1) and high stability are also recorded. This work provides a facile, scalable, and template-free approach to convert biomass into highly active electrochemical catalysts, which shows great potential for future applications.