Preparation Of Three-dimensional Structure Coating TiO_2-x For Photocatalytic And Photothermal Conversion

Global water scarcity and pollution problems have seriously affected the development of human society.Solar energy use for wastewater treatment,including photocatalytic degradation of organic pollutants and solar-driven water evaporation,is an effective way to solve this problem.As a kind of photocatalyst,TiO₂ has attracted wide attention in the field of photocatalysis because of its environmentally friendly,non-toxic,stable and high active sites.However,due to the large band gap of TiO₂,the photoresponse range is narrow and the quantum efficiency is low,which seriously affects the photocatalytic activity.And the recovery of TiO₂ powder catalyst greatly affects its catalytic effect and practicability.Therefore,it is necessary to modify TiO₂and achieve effective immobilization,and improve the photocatalytic performance of TiO₂ while imparting its solar-driven water evaporation performance.In this paper,a bifunctional composite material was prepared and treated with solar energy for water treatment.Ti³⁺doped TiO₂(TiO_2-x)was prepared by commercial TiO₂?P25?using hydrothermal and chemical reduction methods.The hydrothermal time and reduction temperature which could affect the of morphology and structure TiO_2-x,were investigated by XRD,XPS,SEM and TEM.The results showed that the synthesized TiO_2-x was a band-like morphology with a length of about 2?m and contains Ti³⁺and oxygen vacancies,thus exhibiting broadband solar absorption capacity and excellent photocatalytic performance for malachite green?MG?.The concentration of 10 mg/L MG degraded 99.94%at 50 min.In order to further improved the photocatalytic performance of TiO_2-x,the adhesion of polydopamine?PDA?was used to modify TiO_2-x-x by carbon black?CB?to synthesize CB/TiO_2-x composite photocatalytic material by XRD,SEM,Raman and other test analysis techniques,which wereused to explore the effect of the mass ratio of CB and TiO_2-x on the morphology and properties of CB/TiO_2-x.The results showed that when the mass ratio of CB to TiO_2-x was 1:2,the obtained CB/TiO_2-x had high light absorption performance in the broad spectrum of 250 nm-2500nm and exhibited excellent photocatalytic performance.The target contaminant malachite green solution MG?10 mg/L?could be degraded by 99.95%within 3 min.In order to effectively improve the problem of difficult recovery of the powder catalyst,the synthesized CB/TiO_2-x composite photocatalytic material was sprayed into the 3D printed black polycarbonate three-dimensional structure.Based on the high light absorption properties of the three-dimensional structure of black polycarbonate,on the basis of improving the photocatalytic performance of the CB/TiO_2-x composite photocatalytic material,the solar water-driven water evaporation performance was further imparted.The effects of CB/TiO_2-x concentration and layer number on the structure and properties of CB/TiO_2-x/PC were investigated by XRD,SEM and UV-Vis-NIR.The results showed that when the concentration of CB/TiO_2-x was 15mg/mL and the number of sprayed layers was 3,the obtained polycarbonate-loaded carbon black/TiO_2-x(CB/TiO_2-x/PC)had the best performance.Efficient degradation of MG solution?99.94%?could be achieved within 2 min.After 20 cycles,its catalytic activity had not changed significantly.At the same time,it exhibited excellent light absorption performance?99.7%?and 3 times sunlight evaporation rate reached 4.5371kg/?m²·h?,the photothermal conversion efficiency reached 93.52%.