Enhanced carbonate capture affinity of copper-doped bismuth niobate enables efficient anodic hydrogen peroxide...

The electrochemical synthesis of hydrogen peroxide (H₂O₂) through the two-electron water oxidation reaction (2e^-WOR) offers a sustainable and promising alternative to the conventional anthraquinone process. However, developing anode catalysts with both high selectivity and high production rates remain a formidable challenge due to the competitive four-electron water oxidation reaction (4e^-WOR). Herein, we report a highly efficient copper-doped bismuth niobate catalyst (x% Cu:Bi₃NbO₇) for anodic H₂O₂ production. Electrocatalytic evaluations reveal that the 5% Cu:Bi₃NbO₇ sample delivers a remarkable H₂O₂ Faradaic efficiency of 57.5% and a high production rate of 28.46 μmol min^-1 cm^-2 at 3.18 V vs. RHE in a 2 M K₂CO₃ electrolyte, which are nearly twofold higher than those of the pristine Bi₃NbO₇. After a reaction time of 120 min at this potential, the accumulated H₂O₂ in electrolyte reached 1219.91 ppm. Mechanistic insights obtained from potential- and time-dependent in-situ ATR-FTIR spectroscopy demonstrate that CO₃^2- acts as a reactive mediator, forming peroxycarbonate intermediates (HCO₄^-/C₂O₆^2-) that subsequently hydrolyze to yield H₂O₂. Ex-situ ATR-FTIR further proves that Cu doping significantly boosts the chemical capture affinity toward CO₃^2- species under anodic bias, locking more active species to accelerate H₂O₂ generation. Finally, an integrated flow cell was constructed that achieved a H₂O₂ accumulation of ∼182.33 mmol over 10h continuous operation coupled with cathodic hydrogen evolution and demonstrated rapid environmental remediation via degradation of methylene blue within 20min.