Biomimetic Fe₇S₈/Carbon electrocatalyst from [FeFe]-Hydrogenase for improving pH-Universal electrocatalytic hydrogen production

Efficient and cost-effective electrocatalysts that can operate across a wide range of pH conditions are essential for green hydrogen production. Inspired by biological systems, Fe7S8 nanoparticles incorporated on polydopamine matrix electrocatalyst were synthesized by co-precipitation and annealing process. The resulting Fe7S8/C electrocatalyst possesses a three-dimensional structure and exhibits enhanced electrocatalytic performance for hydrogen production across various pH conditions. Notably, the Fe7S8/C electrocatalyst demonstrates exceptional activity, achieving low overpotentials of 90.6, 45.9, and 107.4 mV in acidic, neutral, and alkaline environments, respectively. Electrochemical impedance spectroscopy reveals that Fe7S8/C exhibits the lowest charge transfer resistance under neutral conditions, indicating an improved proton-coupled electron transfer process. Continuous-wave electron paramagnetic resonance results confirm a change in the valence state of Fe from 3+ to 1+ during the hydrogen evolution reaction (HER). These findings closely resemble the behavior of natural [FeFe]-hydrogenase, known for its superior hydrogen production in neutral conditions. The remarkable performance of our Fe7S8/C electrocatalyst opens up new possibilities for utilizing bioinspired materials as catalysts for the HER.