Xi Yang

Bio: Xi Yang is an academic researcher from Yanshan University. The author has contributed to research in topics: Photocatalysis & Materials science. The author has an hindex of 4, co-authored 7 publications receiving 43 citations.

Recent Achievements in Development of TiO2-Based Composite Photocatalytic Materials for Solar Driven Water Purification and Water Splitting.

Abstract: Clean water and the increased use of renewable energy are considered to be two of the main goals in the effort to achieve a sustainable living environment. The fulfillment of these goals may include the use of solar-driven photocatalytic processes that are found to be quite effective in water purification, as well as hydrogen generation. H2 production by water splitting and photocatalytic degradation of organic pollutants in water both rely on the formation of electron/hole (e−/h+) pairs at a semiconducting material upon its excitation by light with sufficient photon energy. Most of the photocatalytic studies involve the use of TiO2 and well-suited model compounds, either as sacrificial agents or pollutants. However, the wider application of this technology requires the harvesting of a broader spectrum of solar irradiation and the suppression of the recombination of photogenerated charge carriers. These limitations can be overcome by the use of different strategies, among which the focus is put on the creation of heterojunctions with another narrow bandgap semiconductor, which can provide high response in the visible light region. In this review paper, we report the most recent advances in the application of TiO2 based heterojunction (semiconductor-semiconductor) composites for photocatalytic water treatment and water splitting. This review article is subdivided into two major parts, namely Photocatalytic water treatment and Photocatalytic water splitting, to give a thorough examination of all achieved progress. The first part provides an overview on photocatalytic degradation mechanism principles, followed by the most recent applications for photocatalytic degradation and mineralization of contaminants of emerging concern (CEC), such as pharmaceuticals and pesticides with a critical insight into removal mechanism, while the second part focuses on fabrication of TiO2-based heterojunctions with carbon-based materials, transition metal oxides, transition metal chalcogenides, and multiple composites that were made of three or more semiconductor materials for photocatalytic water splitting.

Regulation of carboxyl groups and structural defects of graphitic carbon nitride via environmental-friendly glucose oxidase ring-opening modulation

Abstract: Structural defects and surface functional groups defects engineering in the graphitic carbon nitride (g-C3N4) polymer semiconductor usually has great benefit in optimizing its electron structure and photocatalytic performance. In this study, one type of carboxyl group defects-grafting g-C3N4 was prepared through glucose oxidase treatment on the initial O sites in the g-C3N4, which played multi-functional roles in the generation of carboxyl groups and melon structure defect. FT-IR, XPS and 13C NMR analysis verified the presence of highly favorable carboxyl groups, which was beneficial to the fast separation and migration of photogenerated carriers. The singularity of enzyme mediated defects control of carbon nitride materials was greatly boosted on O-enriched g-C3N4 (OCN) further supporting the overall O sites ring-opening hypothesis. The glucose oxidase (GOD) treated reconstructed g-C3N4 photocatalysts showed narrowed band gaps and fast charge separation ability as verified by UV–vis DRS and electrochemical tests. As a result, the optimized photocatalyst (GOD-OCN-3d) showed a high Cr(VI) photocatalytic detoxification rate of 99 %, which was 6.6 times higher than that of raw g-C3N4 (15 %) in 120 min. These findings open the understanding on precise molecular defects modulation of g-C3N4 via an environmental-friendly enzyme treatment approach, as well as providing a new avenue for understanding the function of structural defects of photocatalysts on prompting charge separation.