Proton-coupled electron transfer activation of peroxydisulfate with phosphorylated zero-valent iron

• Published in: Applied catalysis. B, Environmental Environmental, 2024-09, Vol.352, p.124025, Article 124025
• Main Authors: Liang, Chuan, Liu, Xiufan, Ling, Cancan, Guo, Furong, Li, Meiqi, Zhang, Xiang, Shu, Yiyi, Sun, Hongwei, Ai, Zhihui, Zhang, Lizhi
• Format: Article
• Language: English
• Subjects: Peroxydisulfate activation; Phosphate proton relays; Proton-coupled electron transfer; Zero-valent iron
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2024.124025

Heterogeneous peroxydisulfate (PDS) activation driven by conventional electron transfer (ET) is often frustrated by low thermodynamic driving force and sluggish kinetics. Herein, we propose a proton-coupled electron transfer (PCET) strategy of PDS activation, by utilizing ball-milled phosphorylated zero-valent iron (P-ZVIbm) as a PCET platform. P-ZVIbm efficiently activated PDS to produce SO4•− and •OH for rapid degradation of 4-chlorophenol in a wide pH range of 3.5–10.5, with rate constants 3–62 times those of the ZVIbm/PDS counterpart. PCET mechanism was evidenced by the pH dependent kinetics, kinetic isotope effect, and proton inventory study. The surface-bound phosphates offer flexible pendant protons (P-O-H) through hydrogen bonds, delocalizing electrons of peroxide O to polarize the O-O bond, thereby facilitating the ET from ZVI for O-O bond cleavage. The work demonstrates the superiority of PCET strategy for heterogeneous PDS activation, and shall guide the design of high-performance Fenton-like catalysts. [Display omitted] •PCET significantly promotes the thermodynamics and kinetics of PDS activation.•P-ZVIbm serves as a proof-of-concept PCET platform of PDS activation.•ZVI, water and phosphate are electron/proton donors and proton relay, respectively.•Phosphate offers flexible pendant protons to the O-O of PDS through hydrogen bond.•P-ZVIbm/PDS rapidly removes 4-CP from water over a wide pH range.