Promoted oxygen adsorption on porous CeO₂ cubes with abundant oxygen vacancies for efficient gaseous formaldehyde...

Photocatalytic degradation stands as a promising method for eliminating gas-phase pollutants, with the efficiency largely hinging on the capture of photogenerated electrons by oxygen. In this work, we synthesized a porous CeO₂ single crystal cube with abundant oxygen vacancies as photocatalyst, employing urea as a pore-forming agent and for gas-phase formaldehyde degradation. Compared with the CeO₂ cubes without pores, the porous ones were superior in specific surface area, akin to conventional CeO₂ nanoparticles. The photocatalytic degradation for gas-phase formaldehyde on porous CeO₂ cubes was significantly accelerated, of which degradation rate is 3.3 times and 2.1 times that of CeO₂ cubes without pores and CeO₂ nanoparticles, respectively. Photoelectric tests and DFT calculations revealed that this enhancement stemmed from facilitated oxygen adsorption due to pronounced oxygen vacancies. Consequently, the capture of photoelectrons by oxygen was promoted and its recombination with holes was suppressed, along with an accelerated generation of curial free radicals such as ·OH. This work reveals the pivotal role of surface oxygen vacancies in promoting adsorbed oxygen, proposing a viable strategy to enhance the photocatalytic degradation efficiency for gas-phase pollutants.