Dopant Site Engineering on 2D Co₃O₄ Enables Enhanced Toluene Oxidation in a Wide Temperature Range

Development of cost-effective oxide catalysts holds the key to the removal of toluene, one of the most important volatile organic compounds. However, the catalysts follow varied working mechanisms at different reaction temperatures, posing a challenge to achieving efficient toluene removal over a wide temperature range. Here we report an agitation-assisted molten salt method, which achieves the rational doping on a two-dimensional Co₃O₄ catalyst and forms two different structures of active sites to enhance catalytic oxidation of toluene in specific temperature intervals, enabling a facile tandem design for working in a wide temperature range. Specifically, Co₃O₄ is doped with Cu at the octahedral site (Cu-Co₃O₄) and Zn at the tetrahedral site (Zn-Co₃O₄) to form Cu_Oh-O-Co_Te and Zn_Te-O-Co_Oh structures on the surface, respectively. Mechanistic studies reveal the different working mechanisms of these two active sites toward remarkable performance enhancement at specific temperature intervals, and the improved performance derived from accelerated consumption of intermediates adsorbed on the catalyst surface. Taken together, Cu-Co₃O₄ and Zn-Co₃O₄ achieve excellent toluene purification performance over a wide temperature range. This work provides insights into the mechanism-oriented design of active sites at the atomic level.