Alkali Etching Induced CoAl-Layered Double Oxides with Regulatable Cation and Oxygen Vacancy Defects to Promote the Photothermal Degradation of Methanol

By controlling the alkali etching time, the cation and oxygen vacancies contents of CoAl-LDHs were adjusted. Then CoAl-layered double oxides catalysts (CoAl-LDOs-x) were prepared by calcination and applied to the photothermal catalytic degradation of methanol and acetone under the full spectrum simulated solar illumination. Compared with CoAl-LDOs-0 without alkali etching, CoAl-LDOs-9 with alkali etching for 9 h showed the most superior photothermal catalytic activity and excellent stability. A series of studies had suggested that the most superior activity of the catalyst could be ascribed to the cation vacancy produced by alkali etching, resulting in more Co3+ active sites on the surface. At the same time, alkali etching also produced oxygen vacancy, which accelerated the adsorption and conversion of surface reactive oxygen species (ROS). In addition, the activation effect of light on lattice oxygen and gas phase oxygen was proved by in-situ DRIFTS, and the degradation path of methanol was clarified.