Surface Modification Of Titanium Dioxide Photocatalyst And The Study On Photocatalytic Water Splitting For Hydrogen Evolution Performance

Photocatalytic water splitting for hydrogen evolution,as an easy handling,environmentally friendly and sustainable energy conversion technique,can effectively alleviate the energy shortage and environmental pollution and other urgent problems,which has received extensive attention of researchers in recent years.Titanium dioxide due to its wide source,low price and excellent chemical stability has become an important research hotspot in the field of photocatalysis.However,the disadvantages of titanium dioxide,such as wide band gap,no response to visible light and fast recombination of photogenerated carriers,severely restrain the further development of the material in the field of photocatalysis.Through effective strategies to optimize the band structure of titanium dioxide,enhance the light absorption ability meanwhile reduce the recombination efficiency of photogenerated carriers and accelerate the transfer kinetics of photogenerated charges in the process of photocatalysis,it possesses research value to enhance the photocatalytic performance.Based on this,In（OH）₃-Ti O₂,Bi₂O₃-Ti O₂ and Co（OH）₂-Ti O₂ photocatalysts were successfully prepared under room temperature and atmospheric pressure（25±5°C and 10⁵ Pa）by surface modification with commercial titanium dioxide as the basic material.Investigate the effects of preparation conditions on the composition,phase and microstructure,study the photocatalytic hydrogen evolution performance and mechanism of these materials,and investigate the influence of modification strategy on photocatalytic water splitting for hydrogen evolution activity.The main research contents are as follows:1.In（OH）₃ modified Ti O₂ photocatalyst and the study on photocatalytic water splitting for hydrogen evolution performanceTitanium dioxide,indium chloride and sodium hydroxide were utilized as materials,In（OH）₃-Ti O₂ photocatalysts were successfully prepared under mild conditions,investigate the composition,phase,morphology and microstructure by characterization,and study their photocatalytic hydrogen evolution performance.The results suggest that the In（OH）₃ has successfully modified on the surface of Ti O₂,the modification of In（OH）₃ can broaden the light absorption edge of the material and promote the separation and migration efficiency of photogenerated carriers,therefore enhance the photocatalytic activity for hydrogen evolution..Under the irradiation of300 W Xenon lamp,the photocatalytic hydrogen evolution rate can reach 5813.52μmol·g^-1,and the material remains high photocatalytic activity after cycling of 20 hours.2.Bi₂O₃ modified Ti O₂ photocatalyst and the study on photocatalytic water splitting for hydrogen evolution performanceThe titanium dioxide was basis material,bismuth nitrate and sodium hydroxide were used as raw materials,the Bi₂O₃-Ti O₂ photocatalysts were successfully fabricated by one-step solid-state method and the materials were studied by characterization and photocatalytic hydrogen evolution performance.The Bi₂O₃ was successfully modified on the surface of Ti O₂,it owns great photocatalytic water splitting for hydrogen evolution.The optimal photocatalytic hydrogen evolution rate can reach 12642.98μmol·g^-1,and the photocatalytic activity did not decline obviously after storing for 26months in the air,therefore suggesting the excellent stability.Photoelectric tests further proved that the recombination of photogenerated carriers in the material was obviously inhibited during the photocatalytic process,exhibiting the longer lifetime of photogenerated charges.Under the illumination of 300 W Xenon light,it has the faster migration rate.Investigate the photocatalytic mechanism,the Bi₂O₃-Ti O₂ belongs to Z-scheme heterojunction,it can partly reduce Bi₂O₃ to Bi during the photocatalytic process,and the Bi can work as transmission mediator to efficiently promote the transfer of photogenerated electrons,which is different from the traditional precious metals as transmission mediator,such as Au,Ag and Pt,showing great modification effect.3.Co（OH）₂ modified Ti O₂ photocatalyst and the study on photocatalytic water splitting for hydrogen evolution performanceThe titanium dioxide,cobalt acetate and sodium hydroxide were employed as raw materials,modifying the Co（OH）₂ with visible light response on the surface of Ti O₂ to further boost the response ability of materials in visible light region.The modification of Co（OH）₂ can effectively optimize the energy band alignment,make the conduction band bend towards higher energy level,broaden the light absorption edges of the material,and strengthen the light-harvesting ability simultaneously.The photocatalytic water splitting for hydrogen evolution tests demonstrate that the photocatalytic hydrogen evolution rate of Co（OH）₂-Ti O₂ can reach 21343.01μmol·g^-1 under the illumination of 300 W Xenon light,which is 23-fold superior to commercial titanium dioxide.After cycling tests of 20 hours,the photocatalytic performance did not decline significantly and the chemical composition did not change,indicating the material possesses excellent cycling stability and chemical stability.Co（OH）₂ can act as cocatalyst to efficiently suppress the recombination of photogenerated carriers in material,therefore reinforce the transfer dynamics of photoinduced charges.These studies prepared oxide/hydroxide modified photocatalyst materials based on titanium dioxide as base material,which dramatically boost the photocatalytic hydrogen evolution performance of titanium dioxide,and provide a reference for future design and synthesis of transition metal oxide/hydroxide to replace noble metal modified semiconductor photocatalysts,and improve the photocatalytic activity.