Molulation Of TiO₂ Surface Structure And Their Photocatalytic Performance For Water Splitting

With the increase of the modernization process,the environmental and energy issues become more prominent.To solve this question,solar hydrogen production provides a new idea for environmental pollution and energy shortages.TiO2 is one of the most important catalytic materials for photocatalytic hydrogen production because of its high stability,environmental friendliness and low price.However,it has the disadvantages of large forbidden bandwidth(3.2 eV)and low charge separation efficiency,which limits its industrial application.Due to its high surface energy and large specific surface,TiO2 nanosheets have better photocatalytic properties than bulk TiO2.However,the surface of TiO2 nanosheets with directly exposed Ti and O atoms tends to have low photo-generated carriers,which does not show ideal photohydrolysis performance.At the same time,HF,as a blocking agent,often used in most preparation process of the TiO2 nanosheets,which is not conducive to environmental friendliness.Thus,the surface structure and the photocatalytic hydrogen production of TiO2 nanosheets were studied by modulating the surface functional group of TiO2 nanosheets and replacing HF using HCl.Study on surface functional groups of HF-ROH modified TiO2 nanosheets and its photocatalytic properties.(1)Firstly,the effects of the ROH type on the the surface functionalization and photolysis water performance of TiO2 nanosheets were studied when HF was acted as a blocking agent.The study showed that the introduction of ROH can promote surface carbonylation and Ti-C=O structural group,molutate the ability of hydroxyl surface adsorption and oxygen vacancy concentration(Oads/Olatt).The results showed that the surface carbonylation of TiO2 nanosheets could improve the surface activity of the catalyst.The increase of oxygen vacancy concentration(Oads/Olatt)provides more active sites for catalytic reactions,resulting in an improved photohydrolysis performance.(2)In addition,HF-glycol,as one type of better performance system,was studied in detail with various preparation conditions.The results showed that with the increase of the amount of ethylene glycol,the ultraviolet absorption of the sample increased first and then decreased.The hydrolysis rate of Ti(OBu)4 increased with the increase of HF dosage.The increase of hydrothermal temperature and time is beneficial to the absorption of red shift.The results showed that the catalytic performance decreased with the increase of the amount of ethylene glycol.With the increase of HF dosage,hydrothermal temperature and hydrothermal time,the catalyltic performance first increases and then decreases.Study on surface functional groups of HCl-ROH modified TiO2 nanosheets and its photocatalytic properties.(1)Firstly,the effects of the ROH type on the the surface functionalization and photolysis water performance of TiO2 nanosheets were studied when HF was replaced by HCl.The results show that the heterostructure of rutile type and anatase type TiO2 can be constructed under the action of HCl.The study showed that the introduction of ROH could reduce the particle size of TiO2 nanosheets,promote surface carbonylation and Ti-C=O structural group,molutate the ability of hydroxyl surface adsorption and oxygen vacancy concentration(Oads/Olatt).The results showed that the surface carbonylation and heterostructure of TiO2 nanosheets enhanced the surface activity of the catalyst.With the increase of oxygen vacancy concentration(Oads/Olatt),the performance of photohydrolysis water was significantly improved.(2)In addition,HCl-ethanol,as one type of better performance system,was studied in detail with various preparation conditions.The results showed that the increase of ethanol content was beneficial to the transformation from rutile type to anatase type.The increase of HCl content can promote the growth of rutile type.The increase of hydrothermal temperature and hydrothermal time is beneficial to the transformation from rutile type to anatase type.The catalytic performance showed that the amount of ethanol and the hydrothermal time had little influence on the catalytic performance of the catalyst.With the increase of the amount of HCl and the hydrothermal temperature,the catalytic performance first increased and then decreased.Study on the effect of HC1-RCOOH and HCl-RCHO on the surface functional groups of TiO2 nanosheets and their photocatalytic properties.(1)The effects of RCOOH and RCHO on the surface functionalization and photohydrolysis of TiO2 nanosheets were investigated by introducing different RCOOH and RCHO with HCl as a blocking agent.The study showed that the introduction of RCOOH and RCHO could promote surface carbonylation and Ti-C=O structural group,molutate oxygen vacancy concentration(Oads/Olatt).The catalytic properties showed that the surface carbonylation and the formation of the TiO2 nanosheets heterostructure improved the surface activity of the catalyst,which was beneficial to the separation and migration of photoborne carriers.The increase of oxygen vacancy concentration(Oads/Olatt)provides more active sites for catalytic reactions,resulting in an improved photolysis water performance.The sample prepared by HCl-HCHO had the best catalytic performance with the hydrogen production rate of 12499.1μmo·g-1*h-1.(2)In addition,HCl-HCHO,as one type of better performance system,was studied in detail with various preparation conditions.The results showed that the increase of HCHO content was beneficial to rutile type growth.With the increase of hydrothermal temperature and hydrothermal time,the amount of hydroxyl group adsorbed on the catalyst surface increased firstly and then decreased.The catalytic properties showed that HCHO dosage had little effect on the catalytic properties,which followed the trend of increasing firstly and then decreasing.The effect of time on catalytic performance was not obvious.With the increase of reaction temperature,the catalytic performance increased firstly and then decreased.