Synthesis,Photocatalytic And Adsorption Properties Of Porous Nanostructured Semiconductors

With the rapid development of industry and civilization,environmental pollution is becoming more and more serious.In recent years,developing highly effective adsorbents and photocatalysts for the pollutants removal in wastewater has become a hot topic in chemistry,materials,and environment domains.Rationally controlling the surface and structure of the adsorbents and photocatalysts according to the physical and chemical mechanism in the process of adsorption and photocatalysis,to improve the performance and obtain high-quality materials,is a key scientific problem that has aroused wide attentions.Titanium dioxide?TiO₂?and copper tungstate?CuWO₄?,as two types of cheap,non-toxic oxides with abundant reserve on earth,have great potential in large-scale development and utilization.However,the wide bandgap of TiO₂ greatly limits its optical response range and photocatalytic properties.Although CuWO₄ has a narrow band gap,its high recombination rate of the photo-generated carrier significantly limits its performance and applications.Therefore,we intend to modify these two kinds of semiconductors by means of rational structural regulation and surface modification,so as to improve their light absorption and promote the carrier separation rate,finally achieve efficient removal of pollutants.Based on this,the following studies were carried out:?1?To overcome the disadvantages of TiO₂ in the light absorption range and charge separation,we used the slow photon effect of the 3D ordered macroporous structure to increase the light utilization of TiO₂.At the same time,the doping of Bi³⁺and the decoration of carbon dots?CDs?were carried on to regulate the energy level and the surface properties of TiO₂,thereby increasing the charge conductivity and promoting the rapid separation of photo-generated carriers.Therefore,CDs modified 3DOM Bi:TiO₂ nanocomposites by sol-gel assisted heat treatment method were synthesized.The results showed that the composite has good photocatalytic degradation performance and achieved high photocatalytic degradation of RhB and phenol.?2?The surface area of the adsorbent and the number of active sites are key factors that influence the adsorption performance.We designed CuWO₄ with three-dimensional structure by a convenient and straightforward self-templating method,to improve its adsorption performance.The results turn out that the morphology of CuWO₄ can be regulated by controlling the reaction time of the hydrothermal process to obtain corresponding solid CuWO₄ nanospheres?s-CuWO₄?and hollow CuWO₄ nanospheres?h-CuWO₄?.The as-prepared h-CuWO₄ show faster adsorption rate and higher adsorption capacity towards methylene blue?MB?,revealing the excellent dye removal property of h-CuWO₄.?3?Given the low efficiency of CuWO₄ photocatalyst,we tried to conduct reasonable morphology modification and surface decoration in order to improve the carrier separation efficiency and improve the photocatalytic performance of CuWO₄.Apart from constructing a hollow structure that can effectively improve the light absorption and enhance mass transfer,the interfacial heterostructure between CdS quantum dots and CuWO₄ is also fabricated to enhance electron transmission.Then,the excellent electron conduction and storage ability of CDs was utilized to enhance the separation and utilization rate of photogenerated carriers.The degration experiments indicated that the ternary composite catalyst displays significantly enhanced photocatalytic degradation towards Congo red and phenol.