Sulfur-based Photothermal Materials And Their Applications In Water Decomposition For Hydrogen Production And Ciprofloxacin Degradatio

Energy shortage and environmental pollution are important factors affecting human development.Photocatalysis technology has been considered a new way for solving energy crisis and improving the environment,yet,to date,the reported catalytic efficiency needs to be further improved.The photothermal coupling catalysis can be used to heat the active site in situ and raise the ambient temperature to produce photothermal effect by using photothermal conversion materials,which can obtain higher catalytic efficiency.In addition,the photothermal coupling catalysis can reduce the cost of catalysis due to the external heat input is not required.Here,the semiconductor photothermal materials were selected as the source of thermal effect,and the heterojunctions were constructed to optimize the separation efficiency of photogenerated carriers.Higher efficiency of hydrogen（H₂）production from spiltting water and the enhanced degradation of ciprofloxacin in wastewater were achieved using the prepared sulfur-based composites.The details are as follows:（1）The twin-crystal Zn_0.5Cd_0.5S（ZCS）nanoparticles were dispersed onto oxygen-vacancies-rich Mo O_3-x nanosheets by the method of in situ growth,and the H₂ production performance of Mo O_3-x/Zn_0.5Cd_0.5S（M/ZCS）composites was improved.Mo O_3-x plays the role of killing two birds with one stone,Mo O_3-x can form a Z-scheme system with ZCS to enhance the migration of carriers,at the same time,the photothermal effect of Mo O_3-xprovides external force for H₂ production by heating the active sites in situ.In detail,the highest H₂ production efficiency of the composite sample was 17.81 mmol·g^-1·h^-1 under visible light（λ>400 nm）,which was 17.13 times higher than that of ZCS.In addition,the composite sample has excellent photothermal capability and its photothermal coupling catalysis H₂ evolution is higher than photocatalysis alone,which can reach 22.81 mmol·g^-1·h^-1.And the catalyst exhibited stability and recyclability after the 16 h test.The results showed that the composite has higher charge separation efficiency,both the effective carrier separation and photothermal effect in Z-scheme heterojunction can improve the rate of H₂ production.（2）The hollow nanotube S-scheme heterojunction of Zn_0.5Cd_0.5S/Co₉S₈（ZCS/Co₉S₈）was synthesized,which can not only extend the light collection to near-infrared region to achieve excellent photothermal effect,but also improve the separation efficiency of photo-generated carriers.The optimal ratio showed an efficient H₂ evolution rate of 26.53 mmol·g^-1·h^-1 and the apparent quantum yield at 400 nm reached 47.33%.Moreover,the H₂ production efficiency of photothermal coupling is higher than that of photocatalysis alone.The enhanced H₂ production performance was attributed to the special hollow structure,the broad spectrum absorption of light and the effective charge transfer induced by S-scheme heterojunction.（3）The LaFeO₃/Co₉S₈ heterojunction catalyst（x%CS/LFO）was synthesized by electrostatic self-assembly and used to degrade antibiotic Ciprofloxacin（CIP）in water.The optimal composite can remove 96.81%CIP within 30 min in the photothermal/PMS system,which is higher than that in the photocatalytic,PMS and photocatalysis/PMS system.The effects of different factors on the photothermal/PMS degradation activity of the composite were investigated,the results showed that the system has a wide range of p H adaptation（p H=3-11）and strong anti-interference ability against anions in water.In addition,the optimal composite showed good stability.The reactive species are mainly sulfate free radicals(SO₄^·-),followed by superoxide free radicals（·O₂^-）,hydroxyl free radicals（·OH）and hole（h⁺）.Photocatalysis,PMS and photothermal effect promote the degradation of CIP collectively.