Insight into the Contributions of Surface Oxygen Vacancies on the Promoted Photocatalytic Property of Nanoceria

Abstract

Oxygen vacancies (OVs) have critical effects on the photoelectric characterizations and photocatalytic activity of nanoceria, but the contributions of surface OVs on the promoted photocatalytic properties are not clear yet. In this work, we synthesized ceria nanopolyhedron (P-CeO2), ceria nanocube (C-CeO2) and ceria nanorod (R-CeO2), respectively, and annealed them at 600 °C in air, 30%, 60% or pure H2. After annealing, the surface OVs concentration of ceria elevates with the rising of H2 concentration. Photocatalytic activity of annealed ceria is promoted with the increasing of surface OVs, the methylene blue photodegradation ratio with pure hydrogen annealed of P-CeO2, C-CeO2 or R-CeO2 is 93.82%, 85.15% and 90.09%, respectively. Band gap of annealed ceria expands first and then tends to narrow slightly with the rising of surface OVs, while the valence band (VB) and conductive band (CB) of annealed ceria changed slightly. Both of photoluminescence spectra and photocurrent results indicate that the separation efficiency of photoinduced electron-hole pairs is significantly enhanced with the increasing of the surface OVs concentration. The notable weakened recombination of photogenerated carrier is suggested to attribute a momentous contribution on the enhanced photocatalytic activity of ceria which contains surface OVs.

Catalytic properties of CeO2/TiO2 synthesized by different methods towards the organic dye photodegradation and NH3 selected catalytic removal of NOx

“…Recently, managing the pollution issues including wastewater [1] and hazardous exhaust [2] have attracted many research attentions. Photocatalytic degradation is regarded as a green and environmental friendliness method with low energy consumption [3,4] to purify and remove the organic pollutants in wastewaters. Besides, NO x is one of the most serious air pollutants which may cause problems such as acid rain, photo-chemical smog and PM 2.5 [5,6], and the ammonia selective catalytic reduction (NH 3 -SCR) has been employed for commercially removing NO x [7].…”