Preparation And Photocatalytic Antibacterial Performance Of TiO₂ And G-C₃N₄ Based Heterocomposites

In recent years,due to serious water pollution,more and more pathogenic pathogens are produced in the environment.Infectious diseases caused by pathogenic microorganisms have become one of the growing health problems that cause millions of diseases and deaths each year.Many scientists have explored effective methods of disinfection,including chlorination,ozonation,UV irradiation,and photocatalysis.Among them,photocatalytic disinfection is considered to be one of the most sustainable and cost-effective disinfection processes.Among many photocatalysts,TiO₂ has high application prospects in the field of photocatalysis due to its strong photocatalytic power,low cost,wide source of raw materials,stable performance and no pollution.However,TiO₂ has a wide band gap?3.0³.2 eV?,easy to recombine electron holes,and a narrow range of absorption light??387.5 nm?,which seriously restricts the application of TiO₂ in the photocatalytic direction.The modification of the semiconductor material by ion doping,noble metal deposition,semiconductor loading and the like can greatly improve the photocatalytic performance of the semiconductor material.g-C₃N₄ is a novel non-metal photocatalytic material with narrow band gap?2.8 eV?and strong adsorption capacity,but it has the disadvantages of small specific surface area and easy recombination of electron-hole pairs.In order to improve the photocatalytic performance of g-C₃N₄,it can be modified.The photocatalytic performance of g-C₃N₄ can be greatly improved by heterogeneous compounding with a semiconductor.In this paper,the preparation of transition metal ion doped TiO₂,noble metal deposited TiO₂,g-C₃N₄/Ni-TiO₂ composite and g-C₃N₄/Cu₂O composite was used to explore the photocatalytic ability of various modification methods.influences.Through a series of characterization methods?such as XRD,TEM,FESEM,UV-vis,FTIR,etc.?to explore its structure and properties,E.coli or Fusarium graminearum as a target to evaluate the photocatalytic properties of materials,Explore the factors that affect photocatalytic performance.?1?A sol-gel method was used to prepare a transition metal ion(Fe^3+,Co²⁺,Cu²⁺,Ni²⁺)TiO₂material according to a certain ratio.After ion doping,the TiO₂ material was characterized by a series of characterizations?XRD,UV–vis,FESEM,etc.?.The photocatalytic performance of E.coli was evaluated.The antibacterial effect of Co²⁺and Ni²⁺doping was stronger than that of Fe³⁺and Cu²⁺.The Ni²⁺doped Ni-TiO₂ material had the best effect.Ni²⁺doped TiO₂materials with different proportions?0.25%,0.5%,1%,2%,5%?were prepared,and the photocatalytic performance was evaluated with E.coli as the target.The photocatalytic performance did not increase with ion doping.However,Ni-TiO₂ doped with Ni²⁺at a ratio of0.5%is the best.?2?Using the photodeposition method,the Ag element was deposited on the0.5%-Ni-TiO₂ nanospheres selected from the above experiments according to different ratios?0.5%,1%,2%,5%,10%?to prepare Ni-TiO₂/Ag composite.It was observed by TEM characterization that the silver element was loaded onto the surface of Ni-TiO₂ nanospheres with very small particles.It was found by UV absorption spectroscopy that the Ni-TiO₂/Ag composites showed red shift in the ultraviolet region with the loading of silver.The light absorption in the visible light region is significantly enhanced compared with Ni-TiO₂,and is most obvious when the Ag content reaches 10%.Fluorescence photoluminescence spectroscopy experiments show that the spectral intensity of Ni-TiO₂/Ag composite is significantly better than Ni-TiO₂ is weak;ESR analysis results show that Ni-TiO₂/Ag composites produce a large number of superoxide radicals and hydroxyl radicals during photoirradiation;photocatalytic bacteriostasis targeting Escherichia coli and Fusarium graminearum The performance evaluation showed that the photocatalytic performance of Ni-TiO₂/Ag was better than that of pure Ni-TiO₂,and the photocatalytic activity of Ni-TiO₂/Ag-5%was the best.?3?Using the hydrothermal method,the 0.5%-Ni-TiO₂ nanospheres obtained above were combined with g-C₃N₄ in different proportions?5%,10%,15%,20%,40%?to prepare g-C₃N₄/Ni-TiO₂ composite.It can be seen by FESEM that the Ni-TiO₂ nanospheres are uniformly loaded onto the g-C₃N₄ nanosheets.The UV-visible absorption spectrum shows that the g-C₃N₄/Ni-TiO₂ composites are in the visible region with the increase of the content of Ni-TiO₂ nanospheres.The absorption of the g-C₃N₄/Ni-TiO₂ composite is obviously weaker than that of the pure g-C₃N₄ material.The evaluation of photocatalytic performance with Escherichia coli indicates g-C₃N₄/Ni.-TiO₂ composites have stronger antibacterial effect than pure g-C₃N₄ and Ni-TiO₂.?4?Using the direct precipitation method,Cu₂O was loaded onto the surface of g-C₃N₄according to different ratios?5%,9%,20%,33%?to prepare g-C₃N₄/Cu₂O composite.It can be seen from the FESEM image that the Cu₂O nanospheres are uniformly dispersed on the surface of the flaky g-C₃N₄.UV-vis spectroscopy shows that the composite exhibits better absorption of visible light than pure g-C₃N₄;photocatalytic degradation of TC and Escherichia coli and Fusarium graminearum were the targets.The photocatalytic properties of the composites were evaluated.The photocatalytic activity of g-C₃N₄/Cu₂O composites was stronger than that of pure g-C₃N₄ and Cu₂O.The photocatalyst was explored using chemical scavengers.The possible mechanism of bacteriostasis indicates that·O₂-,·OH and h⁺play an important role in photocatalytic bacteriostasis.