Highly Efficient Degradation of Persistent Pollutants with 3D Nanocone TiO₂-Based Photoelectrocatalysis

Abstract

Photoelectrocatalytic (PEC) degradation of organic pollutants into CO2 and H2O is a promising strategy for addressing ever-growing environmental problems. Titanium dioxide (TiO2) has been widely studied because of its good performance and environmental benignancy; however, the PEC activity of TiO2 catalyst is substantially limited due to its fast electron–hole recombination. Herein, we report a TiO2 nanocone-based photoelectrocatalyst with superior degradation performance and outstanding durability. The unique conical catalyst can boost the PEC degradation of 4-chlorophenol (4-CP) with 99% degradation efficiency and higher than 55% mineralization efficiency at a concentration of 20 ppm. The normalized apparent rate constant of a nanocone catalyst is 5.05 h–1 g–1 m2, which is 3 times that of a nanorod catalyst and 6 times that of an aggregated particle catalyst, respectively. Further characterizations reveal that the conical morphology of TiO2 can make photogenerated charges separate and transfer more efficiently, resulting in outstanding PEC activity. Moreover, computational fluid dynamics simulations indicate that a three-dimensional conical structure is beneficial for mass transfer. This work highlights that tuning the morphology of a photoelectrocatalyst at the nanometer scale not only promotes the charge transfer but also facilitates the mass transportation, which jointly enhance the PEC performance in the degradation of persistent pollutants.

Mechanistic Insights into Selective Acetaldehyde Formation from Ethanol Oxidation on Hematite Photoanodes by Operando Spectroelectrochemistry

“…Further formaldehyde oxidation to formic acid on TiO 2 over reaction time was observed in both PEC [5b] and transient absorption [5d] measurements, which is not observed in our study herein using α‐Fe 2 O 3 , indicative of the difference in thermodynamic activation barrier causing different reaction pathway. Our results indicating the thermodynamic and kinetic challenge for the oxidation of organic molecules is further supported by a recent study of oxidation reactions using TiO 2 for complete removal of persistent organic pollutants [3a] . In addition, the difference of faradaic efficiency for PEC methyl phenyl sulfide oxidation has been reported using TiO 2 (2.3–13.8 %) and α‐Fe 2 O 3 (>85 %) [3c] .…”

Understanding the morphology evolution of 1D BiVO4 nanoarrays from nanorods to nanocones with enhanced photocatalytic performance

“…We were encouraged by reports of the superior performance possible by utilizing the conical structure TiO 2 , in which NC TiO 2 arrays have exhibited significantly improved efficiency relative to the NRs due to the promoted charge separation and mass transport. 51,52 To verify the NCs was up to 99% in 90 min under visible light irradiation, which was much higher than for the NRs sample under the same conditions (ca. 33%, Fig.…”

Raspberry-like TiO2 hollow spheres consisting of small nanocrystals towards efficient NO removal

“…The characteristic peaks of rutile TiO 2 were not found for THS, and the XRD peaks at 25.3°, 38°, 47.8°, and 54.8°c orresponded to the (101), (004), (105), and (204) planes of anatase TiO 2 , respectively. 44 The composition of P25 not only contained anatase, but also included the XRD peaks of (110), ( 101), (111), and (220) crystal planes of rutile, which were located at 27.5°, 36.1°, 41.3°, and 56.7°, respectively. 45 Compared with THS-4, the XRD peaks of THS-1 were more sharp, which indicated the poor crystallinity of THS-4.…”