| Photocatalytic technology driven by solar energy has the characteristics of universality,sustainability and environmental friendliness,which is expected to become an effective method to solve the energy crisis and environmental pollution.The construction of efficient and practical photocatalytic materials is a research hotspot in the field of photocatalysis.Among all kinds of photocatalysts,Ti O2is one of the most widely studied photocatalysts because of its non-toxic,low cost and excellent chemical stability.However,the large band gap and high carrier recombination rate limit the efficient utilization of solar energy for Ti O2.In this paper,in order to improve the separation of photogenerated carriers,two different types of heterojunction systems,powder material Cu Co2O4/Ti O2and sheet material CZS/C/Ti O2(Cd0.5Zn0.5S/CQDs/Ti O2),were constructed by means of morphology control and semiconductor composite modification,respectively.The structural characteristics,photoelectric properties,photocatalytic performance and reaction mechanism of each system were investigated.The main research contents are as follows:?1?The powder Ti O2rectangular nanosheets were prepared by a solvothermal method,and then Cu Co2O4nanoparticles were loaded on the surface of Ti O2nanosheets by coprecipitation method.The results showed that the Cu Co2O4nanoparticles with the size of8 nm were uniformly loaded on the ultra-thin Ti O2nanosheets by interface bonding,which was conducive to the bulk and interphase transfer of carriers.The introduction of Cu Co2O4can significantly enhance the specific surface area and photocurrent density of Ti O2,reduce the carrier transfer impedance and hydrogen production overpotential,indicating the Cu Co2O4/Ti O2p-n junction system with interface bonding can effectively promote the separation and migration of photocarriers and the surface hydrogen production reaction.In the photocatalytic H2generation test,10%-Cu Co2O4/Ti O2showed the superior photocatalytic activity.The hydrogen production rate reached 4830?mol·g-1·h-1,which was32 times of the pure Ti O2.In addition,it was found that Cu Co2O4/Ti O2had good hydrogen production stability through the circulation experiment and XRD patterns.?2?Sheet Ti O2nanofilms were prepared by a solvothermal method on the basis of titanium sheet.The morphology and structure of the Ti O2nanofilms were controlled by alcohol added at the beginning of the reaction.It was observed that three kinds of Ti O2nanofilms were successfully prepared,i.e.grass like,net like and rod like.And the Ti O2nanofilms had a unique light absorption performance due to the"slit effect".In the photocatalytic H2generation test and cycling experiments,the rod-shaped Ti O2nanofilm exhibited the best hydrogen production activity and stability.Therefore,the rod-shaped Ti O2nanofilm was selected as the object to carry out composite modification.?3?CQDs and CZS were loaded on the surface of rod-shaped Ti O2nanofilm by solvothermal and refluxing methods.The microstructures of CZS,CQDs and Ti O2nanorods in contact with each other were observed.Compared with the binary CZS/Ti O2nanofilm,the introduction of CQDs can enhance the photocurrent density and reduce the internal resistance.At the same time,it was proved that CQDs played an electronic mediator between CZS and Ti O2through the hydroxyl radical trapping experiment,and carriers can be effectively separated by the Z-type transfer route through CQDs.Compared with binary composite,CZS/C/Ti O2nanofilm showed superior photocatalytic activity,and its hydrogen production rate reached 31.0?mol·g-1·h-1,which was 3.4 times of that of pure Ti O2.Furthermore,the cycle experiment showed the good hydrogen production stability of CZS/C/Ti O2nanofilm. |
PDF Full Text Request