Preparation Of Silver Tungstate/MXenes-based Composites And Their Photocatalytic Degradation Of Antibiotics In Water

In recent years,tetracycline hydrochloride（TC）and sulfadimethylpyrimidine（SFE）have been listed as pollutants of concern due to their molecular complexity,highly stable biological activity and the indiscriminate use of final release into water bodies with significant persistence in environmental matrices.The photocatalytic technology,light energy as a source of power,has more obvious advantages than traditional processes in removing such organic pollutants based on sustainable energy.However,there are many problems with the current degradation of the photocatalytic materials designed in such antibiotics.Taking a single silver-based material as an example,its application have greatly restricted for the poor stability,easy oxidation and easy aggregation.Therefore,it is still a great challenge to improve the photocatalytic reduction reaction efficiency and reveal the removal behavior of organic pollutants and materials.Based on this scientific problem,MXene is used as a cocatalyst to construct an Ag₂WO₄/MXene Schottky junction for photocatalytic removal reaction from the perspective of improving the photocatalytic activity of a single silver-based material.It evaluated the photocatalytic performance of the prepared materials using TC and SFE as the target degradation objects,further studied the physical and chemical properties of the materials and investigated the mechanism of the degradation reaction using photoelectrochemical testing methods and liquid-mass spectrometry（HPLC-MS）.The specific research results are as follows:（1）Through the recombination of semiconductors,it studied the process of charge generation,separation,migration at the interface between the Ag₂WO₄and the MXenes surface.with the help of X-ray photoelectron spectroscopy（XPS）characterization,it found that Ag₂WO₄nanoparticles acted as electron donors and Ti₃C₂carriers served as sites for TC and SFE adsorption and"electron reception"（the donated electrons were enriched on the Ti₃C₂surface after the formation of schoenter junction）.It not only improved the reactive sites for catalytic degradation,but protected Ag₂WO₄by inhibiting the return of photogenerated electrons to photosensitive materials.Through characterization of the photoelectric properties of the monomer catalyst and the composite catalyst,and fitting the time-resolved transient photoluminescence spectroscopy（TRPL）data,it was found that the carrier lifetime（34.5μs）of the Ag₂WO₄/Ti₃C₂composite was 16 times higher than that of the Ag₂WO₄nanoparticles（2.12μs）,and the composite had smaller carrier transport resistance and higher photocurrent characteristics than any cell body.The above results showed that Ti₃C₂introduction of nanosheets with the schottky-junction formed by Ag₂WO₄which greatly improved the photocatalytic activity of the materials.（2）It constructed the Ag₂WO₄/Ti₃C₂composite catalytic material with schottky-junction and carried out the antibiotic catalytic removal experiment.The experimental results showed that the schottky-junction material has the best TC and SFE removal efficiency of 62.9%and 88.6%,respectively at the mass ratio of carrier Ti₃C₂and Ag₂WO₄was 1:20（recorded as 5%Ag₂WO₄/Ti₃C₂）.At the experiment of active groups produced in the photocatalytic reaction process,it was found that the photocatalytic active groups were mainly composed of photogenerated holes（h⁺）and·O₂^-.Finally,HPLC-MS means were used to facilitate understanding of the behavioral processes of degradation TC and SFE and the adsorption-degradation of TC/SFE solution by constructing a Ag₂WO₄/Ti₃C₂schottky-junction,which found it occured aldehyde groups,deamination groups,ring opening and oxidation reaction under the attack of active substances while SFE carried out N-S bond cleavage,hydroxylation,aniline oxidation and other processes.And the intermediate products are further mineralized into CO₂、H₂O and other small matter molecules.