Regulating Surface Dipole Moments of TiO2 for the pH-Universal Cathodic Fenton-Like Process

Xiaocheng Liu; Guangyu Bi; Yanyan Fang; Cong Wei; Junsheng Song; Yi-Xuan Wang; Xusheng Zheng; Qian Sun; Yang Wang; Gongming Wang; Yang Mu

doi:10.1021/acs.est.4c02577

Regulating Surface Dipole Moments of TiO₂ for the pH-Universal Cathodic Fenton-Like Process

Environ Sci Technol. 2024 May 1. doi: 10.1021/acs.est.4c02577. Online ahead of print.

Authors

Xiaocheng Liu^{1

2}, Guangyu Bi¹, Yanyan Fang², Cong Wei², Junsheng Song¹, Yi-Xuan Wang¹, Xusheng Zheng³, Qian Sun⁴, Yang Wang^{1

5}, Gongming Wang², Yang Mu¹

Affiliations

¹ CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei 230026, China.
² Department of Applied Chemistry, University of Science and Technology of China, Hefei 230026, China.
³ National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, China.
⁴ CAS Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
⁵ Department of Colloid Chemistry, Max Planck Institute of Colloids and Interfaces, 14476 Potsdam, Germany.

PMID: 38691809
DOI: 10.1021/acs.est.4c02577

Abstract

Although electro-Fenton (EF) processes can avoid the safety risks raised by concentrated hydrogen peroxide (H₂O₂), the Fe(III) reduction has always been either unstable or inefficient at high pH, resulting in catalyst deactivation and low selectivity of H₂O₂ activation for producing hydroxyl radicals (^•OH). Herein, we provided a strategy to regulate the surface dipole moment of TiO₂ by Fe anchoring (TiO₂-Fe), which, in turn, substantially increased the H₂O₂ activation for ^•OH production. The TiO₂-Fe catalyst could work at pH 4-10 and maintained considerable degradation efficiency for 10 cycles. Spectroscopic analysis and a theoretical study showed that the less polar Fe-O bond on TiO₂-Fe could finely tune the polarity of H₂O₂ to alter its empty orbital distribution, contributing to better ciprofloxacin degradation activity within a broad pH range. We further verified the critical role of the weakened polarity of H₂O₂ on its homolysis into ^•OH by theoretically and experimentally investigating Cu-, Co-, Ni-, Mn-, and Mo-anchored TiO₂. This concept offers an avenue for elaborate design of green, robust, and pH-universal cathodic Fenton-like catalysts and beyond.

Keywords: H2O2 activation; TiO2; cathodic fenton-like; dipole moments; pollutant decontamination.