Preparation And Photocatalytic Performance Of Composite Photocatalysts Based On TiO₂ With Micro-nano Structures

Anxiety about depletion of fossil fuel reserves and pollution resulted from the combustion of fossil fuels make hydrogen an attractive alternative energy source.Over the past few decades,photocatalytic water-splitting has become a promising way for a clean,low-cost and environmentally friendly production of hydrogen by using solar energy.As a semi-counductor photocatalyst,TiO₂ has been widely used because of its unique advantages.However,the photocatalytic efficiency of TiO₂ for water-splitting is limited due to the high recombination rate of photogenerated electron-hole pairs.Furthermore,anatase TiO₂ is only effective under ultraviolet irradiation due to its large band gap?3.2 eV?.Usually,sunlight contains about 4%ultraviolet light only.In order to widen visible-light responsive region,cocatalyst based on TiO₂photocatalyst need be exploited.Hierarchal TiO₂ spheres have been synthesized through a facile hydrothermal method under alkaline conditions.Ammonium tetrathiomolybdate is introduced into the reaction system to be reduced to MoS₂.TEM has revealed that MoS₂ can readily loads on the TiO₂surface.The optimum loading amount of MoS₂ is investigated and the optimum photocatalytic water splitting activity is improved by 22.3%.The reason why it can enhance the photocatalytic activity lies in the efficient charge separation.The present work opens an avenue to the synthesis of MoS₂ loaded on the hierarchal TiO₂ spheres.Solvothermal method is developed to incorporate the transition metal into TiO₂@MoS₂composite so that the photocatalytic activity is improved.Photocatalytic H₂ evolution test suggests MoS₂/TiO₂/Ni?Co?S nanocomposite shows superior photocatalytic activity,meanwhile,the optimum H₂ production rate achieves 754.9?mol?h^-1?g^-1 and is about 2.36 times higher than that of TiO₂@MoS₂,which could be attributed to its enhanced visible-light responsive property and improved photcatalytic activity.As a matter of fact,this is an example of which the nickel or cobalt is incorporated into the TiO₂@MoS₂ to dramatically enhance photocatalytic H₂ activity.TiO₂ thin film is successfully prepared on the fluorine doped tin oxide substrate.TiO₂ thin film has a micro-nano hierarchical structure with some protuberance on the top of the rod.The Ag loading is realized by the reduction of N-N dimethyl formamide.TiO₂@Ag exhibits superhydrophobic abilitiy with static contact angle 151^°after modification with 1-dodecanethiol.The wetting state is changed to hydrophilic with the contact angle to be 10°under the ultraviolet illumination.Besides,photocatalytic degradation property on different photocatalysts?modfication with 1-dodecanethiol and different wetting state?is investigated and the results show that the photocatalyst exhibits good degradation activity over RhB.