Enhanced direct hole oxidation of titanate nanotubes via cerium single‐atom doping for photocatalytic degradation of pollutants

Abstract

Abstract Enhancing the activity of photocatalysts is a critical challenge for improving the photocatalytic degradation of contaminated wastewater. Here, a novel Ce single‐atom‐doped titanate nanotube photocatalyst (Ce‐H 2 Ti 2 O 5 ·H 2 O) was successfully synthesized using a one‐pot solvothermal method. Degradation experiments revealed that the optimal Ce doping ratio was 1.0%. The ultraviolet–visible diffuse reflectance spectroscopy results showed that the bandgap of the Ce‐doped sample decreased from 3.02 to 2.87 eV, enhancing the absorption in the visible spectral range. At the same time, the Brunauer–Emmett–Teller specific surface area increased from 63.68 to 88.95 m 2 g −1 . The 1.0%Ce‐H 2 Ti 2 O 5 ·H 2 O (HTC 1 ) could degrade 99.04% of 100 mg L −1 rhodamine B (RhB) after 40 min of visible‐light irradiation. The degradation efficiency decreased by only 21.24% after five cycles. The results of free‐radical quenching and electron spin resonance spectroscopy analyses indicated that HTC 1 achieved efficient degradation of RhB through a direct hole oxidation mechanism. Compared with pure protonated titanate nanotubes (H 2 Ti 2 O 5 ·H 2 O), HTC 1 had a higher specific surface area, more electron traps, narrower bandgap, longer hole lifetime, and suppressed photogenerated charge recombination rate owing to the Ce single‐atom doping.