Synthesis of CoWO4/g-C3N4 Z-scheme heterojunction for the efficient photodegradation of diazinon with the addition of H2O2.

Pesticides are on the list of substances that are routinely monitored by agencies and organizations in various natural environments and habitats. Diazinon (DZN) is the active ingredient in more than 20 agricultural pesticides, it causes the most damage and has been prohibited in many countries around the world. The final product CoWO4/g-C3N4 Z-scheme heterojunction was successfully synthesized in this work, where CoWO4 nanoparticles were deposited on the surface of g-C3N4. CoWO4/g-C3N4 structure allowed for the efficient separation of photo-generated electron-hole pairs, with electrons at the CoWO4 CB migrating to the g-C3N4 VB and preserving the electrons at the g-C3N4 CB and holes in the CoWO4 VB. The photodegradation efficiency of DZN using CoWO4/g-C3N4 Z-scheme heterojunction was investigated, as compared with its precursors, such as CoWO4, and g-C3N4. CoWO4/g-C3N4 Z-scheme heterojunction demonstrated the highest degradation capacity for DZN removal. Based on the results, the photocatalysis of the CoWO4/g-C3N4 Z-scheme heterojunction can be recycled for the effective removal of DZN by simple washing after three runs, proving the heterojunction's stability and suggesting CoWO4 as a promising material for the removal of DZN from contaminated water sources.

Electronic transfer as a route to increase the chemical stability in gold and silver core-shell nanoparticles.

This review article presents the collected recent findings and advancements in understanding and manipulating the electronic properties of the Au/Ag NP system from the standpoint of controlling the characteristics of heterostructured core-shell NPs. The discovery of the electronic transfer effect through analysis of both Ag-Au and Au-Ag type NPs inspired the analysis of the resulting enhanced properties. First, the background on the synthesis and characterization of Ag, Au, Ag-Au, Au-Ag and Au-Ag-Au NPs, which will be used as a basis for studying the electronic transfer and stability properties is presented. Next, Mie Theory is used to inspect the optical properties of the Ag-Au NPs, revealing subtle structural characteristics in these probes, which has implications to the plasmonic properties. This is followed by the inspection of the electronic properties of the Au-Ag NPs primarily through XPS and XANES analysis, revealing the origins of the electronic transfer phenomenon. The unique electronic properties are then revealed to result in improved particle stability in terms of susceptibility to oxidation. Finally, an assessment of the resulting enhanced plasmonic sensing properties is discussed. The results are presented in terms of synthesis technique, material characterization, understanding of the electronic properties and manipulation of those properties to create Au-Ag NPs with enhanced resistance to oxidation and galvanic replacement.