Engineering Cr−O−Ti structure towards boosted vinyl chloride destruction: Oxygen species evolution and reaction mechanism

Revealing the mechanism behind active oxygen species in chlorinated volatile organic compounds (CVOC) destruction is crucial but challenging. Herein, we designed a chromium-substituted titanium bimetal catalyst with strengthened element interaction, exhibiting remarkable ability to activate oxygen and destroy intermediates. Encapsulated chromium species triple the electron transfer speed (Cr → TiO 2 ), converting 90 % of vinyl chloride at 244 °C. The constructed Cr 6 + −O−Ti 3+ structure distorts TiO 2 lattice, generating defects that promote oxygen species activation. In-situ technologies and DFT calculations demonstrate that vinyl chloride adsorbed at Cr 6+ =O sites is oxidized by lattice oxygen, forming C O species, while surface oxygen activates in a cyclic process, promoting the *CH 2 CH to *CH 2 CHO and CH 2 CO. The constructed Cr-O-Ti structure breaks the rate-limiting step of *CH 2 CHO to CH 2 CO process, accelerating the formation of *CH 3 CO and further promoting the deep oxidation process (*CHO + *CO). This work presents new findings towards CVOC highly efficient purification, showcasing significant application potential.