The use of titanium oxide nanotube arrays as photoelectrocatalytic materials has recently attracted significant attention of researchers owing to their excellent properties. However, the low photoelectrocatalytic efficiency of titanium dioxide has posed a great challenge to their application due to the high recombination rate of the electrons and holes as well as the wide band gap. As such, effective approaches for overcoming these limitations are highly desirable.
Constructing heterostructures of TiO2 and g-C3N4 have been proved useful to improve electron-hole separation efficiency and enhance photocatalytic performance due to their appropriated band levels. The heterostructure interfaces between the coupled photocatalysts is important for the transfer of photogenerated electron and hole. It is believed that a large amount of surface defects at the solid-solid contact interface can play the role of ohmic contact by theoretical analysis, because the interfacial defects can act as the centres for charge carrier trapping. Therefore, construction of interfacial oxygen vacancy layers has been identified as a promising solution for enhancing the photoelectrochemical performance of g-C3N4 /TiO2 nanocomposites.
To this note, Henan University researchers: Limin Xiao, Dr. Taifeng Liu, Prof. Min Zhang, Prof. Qiuye Li and Prof. JianjunYang assessed the feasibility of improving the photoelectrochemical performance through zero-dimensional graphitic carbon nitride nanoparticles and one-dimensional and titanium dioxide nanotube arrays. Fundamentally, the heterostructures comprised of oxygen vacancy layer fabricated through a three-step method comprising of vapor deposition, anodic oxidation, and NaBH4 reduction. Also, a series of photoelectrochemical analysis was conducted to determine the factors influencing the photoelectrochemical performance. Their research work is currently published in the research journal, ACS Sustainable Chemistry and Engineering.
The authors observed significant improvement in the photoelectrochemical performance due to the introduced interfacial oxygen vacancy layer as well as the coupled g-C3N4. For instance, the coupled nanocomposite recorded a higher photocurrent density of 0.72mA/cm2 under visible light irradiation as compared to that without oxygen vacancy layer.
In summary, the Henan University scientists successfully demonstrated an efficient method for improving the photoelectrochemical performance. To actualize their study, they conducted a hydroxyl fluorescence characterization in conjunction with density functional theory computations. This confirmed the generation of Z-scheme heterostructure that equally contributed to the improvement of the photoelectrochemical performance attributed to the introduced oxygen vacancy layer between the TiO2 and g-C3N4. Altogether, the study provides vital information that will pave way for design and fabrication of advanced heterostructure photoanodes for various photoelectrochemical splitting applications.
Xiao, L., Liu, T., Zhang, M., Li, Q., & Yang, J. (2018). Interfacial Construction of Zero-Dimensional/One-Dimensional g-C3N4 Nanoparticles/TiO2 Nanotube Arrays with Z-Scheme Heterostructure for Improved Photoelectrochemical Water Splitting. ACS Sustainable Chemistry & Engineering, 7(2), 2483-2491.Go To ACS Sustainable Chemistry & Engineering