形貌、表面异质相结调控对促进Ag2CO3光催化活性和稳定性机理研究

Recent years, the promotion of the quantum conversion efficiency and sability in photocatalytic reactions has become the research hot spot in photocatalysis field. The photocatalytic materials with large spectrum responsible range, high activity, high photocatalytic stability,and environmental friendly are crucial to enlarge the application of photocatalytic technology in environmental purification. In order to overcome the insurmountable problems of poor stability, photocorrosion, without practical application and secondary environmental pollution for silver-based semiconductor photocatalytsts, this research proposal suggested that choosing Ag2CO3 as the representative of silver-based semiconductors, applying sonochemical, hydrothermal, solvotherma, aqueous precipitation methods to prepare Ag2CO3 crystals with morphology of nano(micro) microspheres, nano(micro) rods, nano(micro) cubs. Then different surface heterojunctions of Ag2O/Ag2CO3, Ag/Ag2O/Ag2CO3, AgCl(Br,I)/Ag2CO3, Ag2S/ Ag2CO3, TiO2/Ag2CO3, ZnO/Ag2CO3, WO3/Ag2CO3 were fabricated over the surface of Ag2CO3 crystal through the strategies of phase-transformation, anion exchange, dissolution -recrystallization, and sol-deposition processes. Formation of special morphology and surface heterojunctions could greatly enhance the photocatalytic activity, photocatalytic stability, and photocorrosion resistance of Ag2CO3 in photocatalytic reaction.. The influences of the fabrication conditions on the properties of Ag2CO3 crystals and the surface heterojunctions in Ag2CO3 will be investigated and analysed in details. The structure property of the heterojunction Ag2CO3 composites will be characterized and investigated by some advanced technology, such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM), high resolution- transmission electron microscopy (HRSTEM), Raman spectroscopy, thermogravimetric analysis (TGA), energy-dispersive X-ray (EDX) spectroscopy, photo-luminescence spectroscopy (PL), electrochemistry, Brunauer–Emmett–Teller (BET) surface areas, and etc..The formation mechanism of Ag2CO3 crystals with special morphology and the surface of heterojunctions in Ag2CO3 will be investigated and clarified. The influences of the morphology and surface heterojunctions on the photocatalytic degradation rate and photocatalytic degradation route of model pollutants, photocatalytic stability and photocorrosion resistance of the Ag2CO3 photocatalyst will be characterized and investigated in detail. The reason and mechanism of the enhancing role of the morphology and hetero -structure in photocatalytic activity and stability of Ag2CO3 will be illuminated.. This research project will enrich the new theory and knowledge of the photocatalytic materials and has the positive role in design and fabrication of the Ag-based semiconductor materials with large spectrum responsible range, high activity, and high photocatalytic stability.

为克服银基半导体光催化剂稳定性差、易发生光腐蚀，无法实际应用的问题，本项目提出以Ag2CO3为代表，采用声化学、水（溶剂）热、液相沉淀等可控合成具有不同形貌的Ag2CO3纳（微）米球、纳（微）米棒、纳（微）米四方体等晶体。然后利用相转变、阴离子交换、溶解再结晶和溶胶表面沉积等策略在其表面生长Ag2O(Ag/Ag2O, AgCl(Br,I)/Ag2CO3,Ag2S(TiO2,ZnO,WO3)/Ag2CO3等异质相结。通过形貌、异质相结的调控大幅提高Ag2CO3光催化活性和抗光腐蚀性能。 考察特殊形貌的Ag2CO3晶体生长条件和相转变、离子交换等制备条件对表面异质结微观结构的影响。研究形貌、表面异质相结对Ag2CO3光催化降解模型污染物的反应速率、反应途径、稳定性和光腐蚀行为的影响规律。利用电化学等手段深入理解并阐明形貌、异质相结对Ag2CO3光催化活性、稳定性增强的原因、内在机理。

本相目从形貌调控，表面异质相结等策略出发， 比较系统的研究了形貌、表面异质相结对Ag2CO3光催化降解模型污染物的反应速率、反应途径、稳定性和光腐蚀行为的影响规律。.（1）研究了超声波场作用对Ag2CO3形貌结构的影响。在超声辐射下，产生还原性H·基团，H·使Ag2CO3中Ag+还原成纳米Ag, Ag沉积在Ag2CO3表面而发生表面等离子共振吸收，增强了Ag2CO3对可见光的吸收能力，同时也生成部分Ag2O，形成异质结结构，提升了光催化性能。研究表明，超声辐射的条件下制备Ag/Ag2CO3等需要在适宜的超声频率以及时间。.(2)研究了水热、溶剂热和沉淀反应等方法合成不同粒径的Ag2CO3纳米结构，如AgCl(Br,I)/Ag2CO3纳米块， Ag2CO3/BiOX(Cl, Br, I)、Ag2CO3/Bi2WO6复合微米球光催化剂。发现耦合卤化银后，主体Ag2CO3的光催化活性有了极大程度的提高，同时其稳定性也得到大幅度提高。这种异质相结提高了光生电子和空穴的分离效率，在卤化银中，效果最为显著的是AgBr。.(3)研究了以阴阳离子交换策略制备Ag2CO3复合微球光催化剂。发现以CaMg(CO3)2微球为模板，采用阳离子交换法（Ag+与Ca2+，Mg2+离子交换）制备多尺度的核壳结构Ag2CO3复合微球光催化剂，具有成本低和性能优越的特点。研究了以银离子S2-和CO32-交换制备核壳结构的Ag2S@Ag2CO3.硫化银可以阻止主体光催化剂Ag2CO3的在水溶液中的溶解，提高其稳定性。.(4) 研究了以气相CO2为原料制备Ag2CO3和Ag2CO3-MgCO3，Ag2CO3-CaCO3和Ag2CO3-BaCO3光催化剂，降低了催化剂的制备成本。.以上策略制备的Ag2CO3基光催化剂具有催化活性高，稳定性好和抗光腐蚀性能强的特点。该项目直接研究内容发表论文SCI论文11篇，其中大类分区1区论文3篇，发表相关论文SCI论文28篇，论文水平较高，如在环境催化权威期刊Applied Catalysis B: Environmental发表影响因子大于14的论文3篇。申报发明专利5项，获批发明专利3项。培养8名毕业硕士研究生。获江西省自然科学一等奖一项，在科学出版社出版编著1部。