Regulating Surface Dipole Moments of TiO 2 for the pH-Universal Cathodic Fenton-Like Process.

Although electro-Fenton (EF) processes can avoid the safety risks raised by concentrated hydrogen peroxide (H 2 O 2 ), the Fe(III) reduction has always been either unstable or inefficient at high pH, resulting in catalyst deactivation and low selectivity of H 2 O 2 activation for producing hydroxyl radicals ( • OH). Herein, we provided a strategy to regulate the surface dipole moment of TiO 2 by Fe anchoring (TiO 2 -Fe), which, in turn, substantially increased the H 2 O 2 activation for • OH production. The TiO 2 -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 TiO 2 -Fe could finely tune the polarity of H 2 O 2 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 H 2 O 2 on its homolysis into • OH by theoretically and experimentally investigating Cu-, Co-, Ni-, Mn-, and Mo-anchored TiO 2 . This concept offers an avenue for elaborate design of green, robust, and pH-universal cathodic Fenton-like catalysts and beyond.