Research on improving carbon oxidation by fluorine doping in carbon-assisted water electrolysis for hydrogen production

Faced with the constraints of the “carbon peaking and carbon neutrality goals”, the electrolysis of water for hydrogen production has received significant attention. However, high energy consumption is one of the problems hindering the industrialization of the technology. A strategy for “sacrificial anode carbon-assisted electrolysis of water for hydrogen production” is thus proposed, which uses the carbon oxidation reaction (COR) instead of the oxygen evolution reaction (OER) to achieve a significant reduction in energy consumption. In particular, F-doped biochar (denoted as F-BC-850) was prepared using a simple two-step carbonization method. The structural properties were analyzed using XRD, SEM-EDS, thermogravimetric, XPS and other characterization techniques. The structure-activity relationship was elucidated by electrochemical tests. The results showed that the energy consumption in 0.5 mol/L H₂SO₄ solution at 10 mA/cm² was 57.9% of the conventional Pt sheet electrode. Characterization results showed that HF generated by the pyrolysis of ammonium fluoride etched the biochar and formed highly active C–F bonds, which improved the oxidation performance of carbon. The addition of F species changed the carbon structure, promoted the decomposition of H₂O molecules to *OH radicals, and thus increased the adsorption ability of carbon atoms for *OH radicals. This work can provide theoretical guidelines for the efficient production of H₂ by carbon-assisted electrolysis of water and high-quality utilization of biomass.