Versatile polydopamine-mediated growth of N and C co-doped hollow porous TiO2 spheres with oxygen vacancies for visible-light-driven oxidation of acetaldehyde

Developing visible-light-responsive TiO 2 -based photocatalysts provides a promising avenue for addressing VOCs pollution. Herein, polydopamine (PDA) template pyrolysis waste was in-situ up-cycled for simultaneous growth of N and C co-doped hollow porous TiO 2 microreactors (H-NT-0.2) in air. The resulting H-NT-0.2 with a highly intact hollow structure, thin spherical shell (∼ 13 nm) and high porosity possesses the highest N and C co-doping ratio and largest oxygen vacancies (OVs) amount, leading to the highest concentration of reactive oxygen species (ROS) among all H-NT- x . A crucial role of OVs in enhancing H 2 O adsorption for the generation of hydroxyl radicals (⋅OH) has been revealed by DFT calculations. As a result, H-NT-0.2 shows the highest photocatalytic oxidation (PCO) efficiency of flowing acetaldehyde gas (90%) under visible light irradiation, which exceeds 3.5 times of commercial TiO 2 (P25)), and outperforms most of the reported photocatalysts. The growth mechanism, as well as the photocatalytic reaction pathways, were analyzed based on TG-MS and in-situ DRIFTS results, respectively. This work provides an economical, green and feasible strategy to develop advanced visible-light-responsive photocatalysts for aldehydes VOCs abatement in practical applications.