Showing papers by "Jeffrey C.S. Wu published in 2020"

Direct and indirect Z-scheme heterostructure-coupled photosystem enabling cooperation of CO 2 reduction and H 2 O oxidation

Abstract: The stoichiometric photocatalytic reaction of CO2 with H2O is one of the great challenges in photocatalysis. Here, we construct a Cu2O-Pt/SiC/IrOx composite by a controlled photodeposition and then an artificial photosynthetic system with Nafion membrane as diaphragm separating reduction and oxidation half-reactions. The artificial system exhibits excellent photocatalytic performance for CO2 reduction to HCOOH and H2O oxidation to O2 under visible light irradiation. The yields of HCOOH and O2 meet almost stoichiometric ratio and are as high as 896.7 and 440.7 μmol g−1 h−1, respectively. The high efficiencies of CO2 reduction and H2O oxidation in the artificial system are attributed to both the direct Z-scheme electronic structure of Cu2O-Pt/SiC/IrOx and the indirect Z-scheme spatially separated reduction and oxidation units, which greatly prolong lifetime of photogenerated electrons and holes and prevent the backward reaction of products. This work provides an effective and feasible strategy to increase the efficiency of artificial photosynthesis. The stoichiometric photoreaction of CO2 with H2O is one of the big challenges in photocatalysis. An artificial photosynthetic system based on a direct and indirect Z-scheme heterostructure is synthesised, enabling simultaneous CO2 reduction to HCOOH and H2O oxidation to O2.

Photocatalytic Degradation of Phenol and Methyl Orange with Titania-Based Photocatalysts Synthesized by Various Methods in Comparison with ZnO–Graphene Oxide Composite

Abstract: Photocatalysis is one of the effective methods to treat wastewater and degrade pollutants. Titania (TiO2) is usually chosen based on its superior properties and its high performance as reported in many publications. However, the properties of TiO2 may be influenced by the synthesis method. In this work, several methods were applied to synthesize TiO2, and its modified form (composite with graphene oxide) to explore the influence of synthesis method on its photocatalytic activity for the methyl orange and phenol degradation under UV light illumination. The results showed that the synthesis method significantly influences on the morphology, particle sizes and surface area of the catalysts as examined by SEM and BET techniques but did not differentiate crystal structure and crystallite dimensions of catalysts as seen by XRD measurement. TiO2 catalyst synthesized by hydrothermal method using P123 template was almost anatase phase, possessed high surface area (110 m2/g) and exhibited highest activity for methyl orange and phenol degradation under UV light illumination. However, the addition of graphene oxide to the catalyst is not yet able to improve its activity under visible light. Compared with ZnO-graphene oxide photocatalyst (almost 100% phenol degraded after 275 min of the treatment), TiO2-graphene oxide catalyst exhibited much less activity for methyl orange and phenol degradation under visible light irradiation.

High Effective Composite RGO/TiO2 Photocatalysts to Degrade Isopropanol Pollutant in Semiconductor Industry

Abstract: This research focused on the photodegradation of aqueous isopropanol in the presence of RGO/TiO2 photocatalysts, which were prepared by the hydrothermal method. Under the irradiation of the simulated sunlight AM1.5G, the photocatalytic activity of isopropanol degradation was studied. In addition, various initial isopropanol concentrations (20, 40, 60, 80, and 100 ppm) were employed in the photocatalytic reaction. P25RGO-0.01% was found to give the highest isopropanol removal of 92.24% at the initial isopropanol concentrations of 20 ppm. Such optimal loading of reduced graphene oxide can act as an electron trapping to suppress the possibility of the recombination of electron–hole pairs. Additionally, acetone was verified to be one of the main in1termediate products. Moreover, it was found that the acidic condition was advantageous to photodegrade isopropanol because of favorable conditions for forming hydroxyl radicals and superoxide radicals. The recyclability test was also verified by three sequent reactions and shown negligible decay of catalysts. This research demonstrated the feasibility of using photocatalysis to remove isopropanol wastewater in sunlight.

Photocatalytic water splitting using hygroscopic MgO modified TiO 2 /WO 3 dual-layer photocatalysts

Abstract: MgO modified TiO2/WO3 dual-layer photocatalysts (DLP) was synthesized by radio-frequency magnetron sputtering (RFMS). The influences of MgO on the properties and the performance of the prepared DLP were investigated. MgO modified TiO2 thin films were characterized by instrumental analysis such as XRD, AFM, SEM-EDS, and UV-visible absorption spectrometry. Their photoactivity was assessed by conducting photovoltammetry followed by splitting water in a twin-cell reactor, where hydrogen gas and oxygen gas were produced separately. The yield of H2 and O2 in the twin-cell reactor corresponded to the photovoltammetry results, indicating that MgO can significantly improve the photoactivity of DLP. The improvement is attributed primarily to the hygroscopic Nature of MgO, which can increase the amount of H2O molecules on the surface of TiO2 for carrying out the photoreaction. In addition, the incorporated MgO layer can also act as an insulator to suppress the electron leakage that occurred at the TiO2-water interface.

Recent advances in the development of photocatalytic NOx abatement

Abstract: This chapter provides a recent aspect of photocatalytic technologies for environmental remediation, in particular, photocatalytic NOx abatement. In detail, a major emphasis is given on discussing the progress and development of photocatalytic NOx abatement. The photo-deNOx could be divided into three significant heads: photo-SCR (selective catalytic reduction), photooxidation, and photodecomposition. In this chapter, extensive attention has been given to the photocatalysts, their photocatalytic performance, and photomechanism. The overall conclusion is drawn with the potential future research direction in the development of photo-deNOx.