Developing high-efficient visible light catalysts: from fabrication to application
Creators: name: Nekouei, Farzin
Publisher: name: The Australian National University
Year: 2023

description: The growing world population and the fast-paced industrial expansion have caused energy shortages and environmental pollution. As a result, it has become crucial to create sustainable and environmentally friendly technologies for the production of green energy and environmental remediation to secure the long-term development of human society. A facile hydrothermal and precipitation approaches was utilised to fabricate porous CdS nanoparticles on polyhedral Cu2O microcrystals on C3N4 and thus enabling to build novel pCdS/Cu2O/g-C3N4 dual p-n Junctions. By incorporation graphitic carbon nitride (g-C3N4) to Cu2O/CdS, leading to a highly efficient bifunctional catalyst for use in environmental rumination and hydrogen generation (ca. 3.3 and 18.4 times enhancement in H2 generation and desalination, respectively). An intergrown InOOH/In2O3 and InOOH/In(OH)3 heterojunction structures were studies to greatly enhance photocatalytic effect for highly efficient decomposition of perfluorooctanoic acid. Fast interfacial charge carrier transferring offers additional charge carriers but does not always occur in the heterojunctions where other effects may play the dominated role in interfacial region. We believe that this comprehensive understanding of intergrown heterojunctions would benefit the design and application of high performance photocatalysts. We have developed a new black catalyst, BixIn2-xO3-R, consisting of Bi atoms on oxygen deficient-laden In2O3. Here, we show how simultaneously Bi ions and oxygen defects could improve light harvesting of the In2O3 synergistically. This catalyst exhibits high visible-light absorption and superior performance in photocatalytic CO2 reduction. First, we activated p-type charge transfer in In2O3 by substituting Bi3+ ions on In3+ sites, denoted as BixIn2-xO3. Further, we created more oxygen defects by treating the rusty-coloured BixIn2-xO3 (x=1.1wt% equals 0.30 atom.%) under a reducing atmosphere at high temperatures, denoted BixIn2-xO3-R (BIO-1.1%-R), to enhance its visible-light harvesting ability. The black BIO-1.1%-R also served as a visible-light responsive photocatalyst for CO2 reduction. We found that the synergistic atomically bismuth substitution and oxygen defects creation in In2O3 remarkably boosted molar selectivity and performance for photocatalytic CO2 reduction under solar-simulated light. We confirmed that Bi doping strategy could be effective in other wide-bandgap materials for light harvesting enhancement as previous study (In2O3). Hence, an additional initial study has been performed by incorporating Bi atoms into Ga2O3 using different concentrations. M-S and SCM techniques indicated the successful p-type charge transfer in Ga2O3. UV-Vis analysis showed an outstanding red shift to 400 nm in the absorption edges for Bi-doped samples and reaches a maximum with 3 wt% of Bi doping, indicating a breakthrough in the field. Additionally, the outcomes confirmed that the same strategy on Ga2O3 was successful as in the previous chapter on In2O3.