The Synthesis Of TiO₂ Nanosheets With Photocatalytic Mechanism Research

With the continuous overexploitation of fossil energy resources,environmental pollution as well as energy crisis has become one of the most serious problems that attract much attention.Semiconductor-based photocatalysis convert solar energy into chemical energy,which becomes one of the most promising strategies to address energy and environmental crisis.Among these newly-developed photocatalysts,titanium dioxide（TiO₂）has been widely studied on account of its low production cost,high photochemical stability,and non-toxicity.However,the photocatalytic water splitting performance of pure TiO₂ is much restricted by the fast recombination of photo-generated charges and large band gap（3.2eV）.Therefore,the development of efficient and sustainable photocatalytic system is a major issue in this field.In view of the above situation,TiO₂ nanosheets are synthesized by Hydrofluoric acid decoration,plate-like Co（OH）₂,Cu₂（OH）₂CO₃ nanoparticles and CoNi-OH nanoparticles are decorated on the surface of TiO₂ nanosheets.Moreover,XRD,TEM,XPS,DRS and SPV are applied to investigate the physic and chemical properties.（1）Plate-like Co（OH）₂ is successfully incorporated onto the surface of TiO₂nanosheets via a facile in-situ synthetic method to give a significantly enhanced photocatalytic H₂ evolution activity.The high evolution rate of H₂ is attributed to the tight interface formed between plate-like Co（OH）₂ and TiO₂ nanosheets,which is favorable for separation and transportation of charge carriers.Based on above results,a possible mechanism is proposed and further verified by surface photovoltage spectra（SPV）.To make a long story in short,Co（OH）₂ has been demonstrated as a promising earth-abundant and low cost co-catalyst for TiO₂ to further enhance its photocatalytic water splitting performance.（2）Noble-metal-free Cu₂（OH）₂CO₃ decorated 2D TiO₂ nanosheets was successfully synthesized via a facile in-situ impregnation synthetic method.The Cu₂（OH）₂CO₃ spherical nanoparticles are dispersed uniformly on the surface of TiO₂nanosheets and form tight interfaces,which plays a vital role in the separation of photo-excited carriers,and formation of active Cu species can also benefit the charge separation process by reducing the over-potential of water reduction.The Cu₂（OH）₂CO₃/TiO₂ hybrid photocatalysts perform a remarkable enhancement in photoatalytic H₂ production even with a small loading amount of Cu₂（OH）₂CO₃.（3）CoNi-OH nanoparticles incorporated onto the surface of TiO₂ nanosheets via a facile in-situ synthetic method and hydrothermal method successfully.XRD,TEM,XPS,and DRS are applied to investigate the physic and chemical properties.The results of photocatalytic hydrogen production indicate that the decoration of CoNi-OH nanoparticles enhance the photocatalytic activity of TiO₂ nanosheets.