| The industrialized manufacture makes people's lives more convenient,however,there also produced plentiful poisonous and harmful organic wastewater in some industries,such as textile industry and printing industry etc.The wastewater can hardly be dealt thoroughly by microorganism,or would make a big cost while it is treated with physical or chemical methods.Semiconductor photocatalytic technology can convert solar energy to chemical energy under mild reaction condition,and further oxidizes and degrades organic pollutant in wastewater,hence it becomes a very promising way to remit environment stress caused by organic wastewater.Graphitic carbon nitride is a kind of new organic semiconductor with outstanding chemical inertness,thermostability and biocompatibility.What's more,it has proper valence band?VB?,conduction band?CB?and band gap,thus it can utilize partial visible light.The above advantages make it to be a promising photocatalyst.The study on g-C3N4 of this thesis mainly focused on its photocatalytic performance,and we have conducted some investigations on its basic properties,and made research on modifying and optimizing g-C3N4 in order to improve its photoactivity.The measures what the study conducted and the experimental results would be listed as follow:?1?Studied on the physicochemical properties and photocatalytic performances among those g-C3N4 that derived from different precursors,the results showed that the conversion yield from melamine to g-C3N4 by the means of thermopolymerization was the highest while urea-derived g-C3N4 showed the highest photoactivity to a large extent.?2?Made a research on what effects it would bring to melamine-derived g-C3N4 by doping Ag,it turned out that doping Ag can improve photoactivity of g-C3N4 effectively,and 10 wt%was the optimal doping content.?3?Melamine,as the precursor,was made into nanoporous g-C3N4?npg-C3N4?through template-induced method,and then npg-C3N4 was further used as template to control SnS2 nanocrystals during the process of hydrothermal synthesis.The results revealed npg-C3N4 had higher BET specific surface area and higher photoactivity comparing with bulk melamine-derived g-C3N4;and it can control size of SnS2 nanocrystals easily by the means of adjusting the additive amount of npg-C3N4.?4?SnS2 quantum dots?SnS2 QDs?could be combined with urea-derived g-C3N4 through solvothermal method,they consisted of semiconductor photocatalyst composites.The results of characterizations and performance tests revealed that urea-derived g-C3N4 and SnS2 QDs comprised semiconductor heterojunction through chemical bonds,which helped suppress the recombination of photo-generated electron-hole pairs and thus the photoactivity was highly improved,in addition,it also can prolong life-span of the photocatalyst because it helped re-separate the charge carriers. |
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