The interplay between selective etching induced cation defects and active oxygen species for volatile organic...

Surface electronic structure of transition metal oxides plays a vital role in determining the catalytic performance. Herein, we present a selective etching strategy to tune the surface cation defect of the CuWO₄ (CW) catalyst for improving the catalytic activity of volatile organic compounds (VOCs). HRTEM, SEM-EDS, EPR, and XPS show that the chelation of metal ions in acetic acid and ammonium hydroxide can help to remove a small number of surface cations in CW to form suitable W defects. Cu L-edge and O K-edge XAS, Raman, and O 1s XPS spectrum illustrate that cation defects can improve the hybrid orbits of metal-oxygen bonds, which increases the activity of surface lattice oxygen and metal sites. In-situ DRIFTS spectra reveal that CW with cation defects can easily adsorb toluene, cleave and oxidize benzene ring, and desorb CO₂ because of more surface dangling bonds and active oxygen species. Therefore, the toluene conversion rates of CW-Aci and CW-Alk are much higher than CW in VOCs degradation and the catalytic performance improved 33 times and 22 times at 200 °C, respectively. This study offers a new pathway in engineering surface electronic structure and highlights the interplay between cation defects and active oxygen species.