The Fabrication And Catalytic Performance Of Defective Brookite TiO₂ Supported Single Atom Cu Catalysts

In recent years,our country’s industrial economy has developed rapidly,and the number of motor vehicles has increased year by year.The production of atmospheric pollutants such as carbon monoxide has caused serious harm to the environment and human health.Catalytic oxidation is one of the most effective and economical technologies in the purification of pollutants.At present,the widely used noble metal catalysts are expensive and have unstable activity at high temperature.Because the off-gas inevitably contains impurities such as sulfur,the noble metals are easily to suffer sulfur poisoning,which triggers catalysts deactivation and seriously hinders further applications.Therefore,there is an urgent need to develop a new type of catalysts to replace the use of noble metals,improve the catalytic performance of the catalysts,and achieve effective removal of gaseous pollutants like carbon monoxide.Due to the low cost,excellent carbon monoxide catalytic oxidation and sulfur resistance,Cu-Ti composite catalysts have been widely studied.However,studies have shown that in Cu-Ti catalysts,the active sites are mainly located at the metal-support interface,which reduces the utilization of atoms,and uneven metal clusters or particle distribution will seriously affect the catalytic performance and selectivity of the catalyst.It is difficult to investigate the catalytic mechanism and efficiently control the oxidation state of Cu.Single-atom catalysts have the largest atom utilization,simple local coordination environment,and easy-to-control electronic structure,which help us to in-depth study of the structure-activity relationship of the catalysts.Therefore,this paper designed and fabricated a single-atom Cu/defective TiO₂ composite catalyst,which has efficient and stable carbon monoxide catalytic oxidation performance and sulfur resistance,and studied the relationship between the structure and performance of the composite catalyst,the details are as follows:We first loaded single atom Cu on the defective brookite TiO₂ nanosheets catalyst（SA-Cu/TiO₂-VO）,used for the catalytic oxidation of carbon monoxide.The results show that SA-Cu/TiO₂-VO has excellent CO catalytic performance.The structural characterization results of the catalysts indicate that the oxygen vacancy clusters effectively increase the amount of adsorbed oxygen and make the surface lattice oxygen more active,providing more active oxygen species required for the reaction.The reduced Cu⁺ makes the adsorption of CO on the catalyst more stable and changes the reaction path of the catalyst.This is the source of the excellent activity and stability of the catalyst.We also applied SA-Cu/TiO₂-VO catalyst to the research of sulfur resistance.The sulfur resistance evaluation results show that the catalyst has excellent sulfur resistance.Due to the unique electronic structure between single-atom Cu and Ti,the amount of sulfate deposited by SA-Cu/TiO₂-VO is less,and at lower temperatures can be decomposed.In summary,we find that oxygen vacancy clusters and reduced Cu⁺can effectively improve the carbon monoxide catalytic oxidation performance and sulfur resistance of the catalysts.This result provides a new idea for the rational design of non-noble metal catalysts with simple structure,low cost and high stability for the controlling of gaseous pollutants.