Among the many materials investigated for photocatalysis, titanium dioxide (TiO2; titania) holds a noble position credit to its impeccable merits such as high photocatalytic activity, excellent physical and chemical stability, low cost, non-corrosive, nontoxicity and high availability. Regardless, much effort has been devoted towards improving its visible light photocatalytic capability. Evidently, researchers have focused on two properties: narrowing the band gap and suppressing the recombination of photogenerated electron‐hole pairs. For this purpose, two approaches are prospectively indispensable: lattice and surface decoration methods. Unfortunately, the aforementioned prospective routes are difficult to combine into one preparation process since they are usually conducted under different conditions, which limits the efficiency of TiO2 modification. The main reason for this shortfall is that C surface decoration is usually conducted under relatively mild conditions, while iron, N‐doping is always carried out under harsher conditions, such as calcination.
Different substances have previously been used as the respective sources for the different introduced elements. To address this, researchers from the Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle in China: Professor Hualin Jiang, Jun Liu, Menglin Li, Dr. Lei Tian, Professor Pinghua Chen，Professor Xubiao Luo together and Gongsheng Ding at the College of Environmental and Chemical Engineering, Nanchang Hangkong University investigated carefully the precursors of introduced elements in previous reports. They utilized Fe and N as dopants, C as the surface decoration element and 4-nitrophenol as the model contaminant by which to study the visible‐light photocatalytic abilities. Their work is currently published in Chinese Journal of Catalysis.
Briefly, the research work encompassed the simultaneous introduction of the aforementioned three elements to TiO2 at high levels via the co‐precursor method. This was closely followed by the in-depth investigation of the as‐synthesized photocatalysts. The as-synthesized photocatalysts were then analyzed by several characterization methods such as XRD, FT‐IR, XPS, Raman spectroscopy, EPR, UV‐Vis DRS, photoluminescence spectra, photocurrent, electrochemical impedance spectra, TEM, and HRTEM. Lastly, the photocatalytic degradation of 4‐nitrophenol under visible‐light irradiation was used to evaluate the photocatalytic activity of the photocatalysts.
Remarkably, metal and non-metal elements were successfully and simultaneously introduced at high levels; whereby the introduced amounts of N and C almost doubled in comparison with previous publications. Better still, the team reported that a homo-structure was formed, and the crystalline phase of the photocatalyst was a mixed phase of anatase and brookite TiO2.
In summary, TiO2 was successfully modified by simultaneous lattice‐doping and surface decoration. Most importantly, the visible‐light photocatalytic capacity of TiO2 was largely improved. Generally, based on the experimental data presented, the study proposed a probable mechanism for the photocatalytic degradation by the photocatalysts. In a statement to Advances in Engineering, Professor Hualin Jiang emphasized that their novel method of using one source to simultaneously introduce metal and non‐metal elements to TiO2 at high levels they presented, will go a long way in providing a new approach of preparing highly effective TiO2 photocatalysts.
Hualin Jiang, Jun Liu, Menglin Li, Lei Tian, Gongsheng Ding, Pinghua Chen, Xubiao Luo. Facile synthesis of C‐decorated Fe, N co‐doped TiO2 with enhanced visible‐light photocatalytic activity by a novel co‐precursor method. Chinese Journal of Catalysis, volume 39 (2018) page 747–759.