Highly efficient persulfate electrosynthesis on boron-doped diamond electrodes via a Ce-SnSbOₓ catalytic layer with enhanced OH selectivity and cycling stability

The electrochemically upgrading sulfate to high-value persulfate (PS) offers significant potential but suffers from impaired selectivity due to competing oxygen evolution reactions (OER). Boron-doped diamond (BDD) electrodes serve as ideal anodes for PS electrosynthesis due to their wide electrochemical window, low adsorption propensity, and superior hydroxyl radical ( OH) generation capacity. Herein, we engineered BDD anodes via a facile one-pot deposition-calcination strategy to construct a Ce 0.1 Sn 2.2 Sb 0.25 O x catalytic layer, dramatically enhancing OH production. The modified electrode exhibited substantially elevated oxygen evolution potential (increasing from 2.726 to 2.905 V vs. RHE), achieved a record Faradaic efficiency (FE) of 90.22 % for PS synthesis at 250 mA/cm 2 , and reached 66.7 μmol/min/cm 2 . The resulting PS solution was concentrated to 1.16 mol/L (15.3 wt%), the highest value reported to date for electrochemical PS synthesis. Electron paramagnetic resonance (EPR) studies confirmed the significant augmentation in OH yields. The incorporation of Sb refined SnO 2 crystallites and strengthened H 2 O adsorption, whereas trace Ce doping markedly improved the stability of catalytic layer and facilitated electron transfer, as evidenced by only a 0.95 % activity loss after 30 successive electrolysis cycles. Mechanistic investigations reveal that the catalytic layer preferentially promotes the indirect oxidation pathways via OH mediation, leading to a marked increase in PS selectivity. This work establishes a simple, cost-effective, and scalable BDD modification strategy with significant industrial potential for electrochemical PS synthesis and waste sulfate resource valorization.