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 → TiO₂), converting 90 % of vinyl chloride at 244 °C. The constructed Cr^{6 +}−O−Ti³⁺ structure distorts TiO₂ lattice, generating defects that promote oxygen species activation. In-situ technologies and DFT calculations demonstrate that vinyl chloride adsorbed at Cr⁶⁺=O sites is oxidized by lattice oxygen, forming C[dbnd]O species, while surface oxygen activates in a cyclic process, promoting the *CH₂CH to *CH₂CHO and CH₂CO. The constructed Cr-O-Ti structure breaks the rate-limiting step of *CH₂CHO to CH₂CO process, accelerating the formation of *CH₃CO and further promoting the deep oxidation process (*CHO + *CO). This work presents new findings towards CVOC highly efficient purification, showcasing significant application potential.