Synthesis And Catalytic Properties Of Ti₃C₂ Photocatalyst Modified By Iron-Series Metal Single Atoms

In order to complete the energy structure transformation as soon as possible and achieve"carbon neutral,carbon peak"grand goal,it is urgent to develop green and stable renewable energy.The photocatalysis water splitting using solar energy to produce hydrogen energy is one of the most promising strategies to ensure long-term energy stability and prevent further environmental degradation,and the selection of photocatalysts is the key to this technology.Ti₃C₂ has been widely studied in the field of photocatalysis due to its semiconductor properties,hydrophilicity and conductivity.However,it has some defects such as narrow light response range and easy recombination of photogenerated carriers,so it is difficult to achieve large-scale application.The introduction of metal single atoms into the photocatalyst can adjust the band structure and electronic structure,further improve the light capture ability and improve the charge transfer kinetics,thus improving the catalytic performance of the photocatalyst.In this paper,the synthesis method and photocatalysis water splitting for hydrogen production performance of iron-series metal single atoms modified Ti₃C₂ were studied.The details are as follows:（1）Multilayer Ti₃C₂ nanomaterials were prepared by acid etching and modified with Fe,Co and Ni atoms respectively.In the test of photocatalysis water splitting for hydrogen production,the hydrogen evolution rate of modified Ti₃C₂ achieved a breakthrough from scratch.Among them,Ti₃C₂ modified by Co single atoms has the best photocatalytic hydrogen production performance,with a hydrogen evolution rate of 707.3μmol·g^-1·h^-1,which is 2.3 times higher than Ti₃C₂ loaded by Pt nanoparticles(Pt-NP_S/TC,with a hydrogen evolution rate of 310.8μmol·g^-1·h^-1).The improvement of photocatalytic performance can be attributed to the following two points:First,the modified Ti₃C₂ has stronger light absorption capacity and larger specific surface area.Secondly,when Fe,Co and Ni atoms are used as cocatalysts,their unsaturated coordination and unique electronic structure can change the adsorption mode and intensity of water molecules and H^*intermediates,and accelerate the formation of H₂.（2）Based on the research in the previous chapter,in this chapter,Ti₃C₂ is modified with two or three atoms of Fe,Co and Ni simultaneously,and their photocatalytic hydrogen production performance was analyzed.The results show that Ti₃C₂ modified by Fe,Co and Ni atoms has the best photocatalytic hydrogen production performance,and the hydrogen evolution rate is 1870.4μmol·g^-1·h^-1,which is 6 times of that of Pt-NP_S/TC.The hydrogen evolution rate of Ti₃C₂ modified by Co and Ni atoms is 1561.4μmol·g^-1·h^-1,which is 5 times that of Pt-NP_S/TC,and more than 2 times of that of Ti₃C₂ with Co and Ni atoms alone.The further improvement of photocatalytic hydrogen production performance is due to the synergy between different metal atoms.（3）On the basis of the previous two chapters,the multilayer Ti₃C₂ nanomaterials were separated into delaminated Ti₃C₂（D-TC）by intercalation and ultrasonic treatment,and modified by metal atoms Fe,Co and Ni respectively.In the test of photocatalysis water splitting for hydrogen production,the hydrogen evolution rate of modified delaminated Ti₃C₂ also achieved a breakthrough from scratch.Among them,Co atoms modified delaminated Ti₃C₂ has the best photocatalysis water splitting for hydrogen production performance,and the hydrogen evolution rate is 799.0μmol·g^-1·h^-1,which is 1.5 times of that of Pt-NP_S/D-TC,and better than that of Co atoms modified Ti₃C₂ in Chapter 1.The photocatalytic performance of delaminated Ti₃C₂ is better because the time and distance of photogenerated electrons and holes transferring from bulk phase to surface are shortened with the decrease of its thickness,which accelerates the charge transfer and thus improves the photocatalytic activity.