Dopant Site Engineering on 2D Co 3 O 4 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 Co 3 O 4 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, Co 3 O 4 is doped with Cu at the octahedral site (Cu-Co 3 O 4 ) and Zn at the tetrahedral site (Zn-Co 3 O 4 ) 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-Co 3 O 4 and Zn-Co 3 O 4 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.