Preparation And Characterization Of TiO₂-based Nanocatalysts

Energy crisis has become increasingly severe over the last decades.Hence,finding some new replaceable clean fuels to replace the fossil fuel seems much urgent than ever.Water splitting has attracted lots of interests since it is an effective way to produce hydrogen fuel as a clean,carbon-free and renewable energy source.Water splitting includes electerocatalysis water splitting and photoelectrochemical water splitting.Among all the photocatalysts studied in these measurements,TiO₂ is one of the most attractive photocatalysts due to its low-cost,stability,and nontoxic properties.However the large scale application of TiO₂ was still restricted due to its slow electrons transfer efficiency and fast electron-hole recombination rate.The one-dimensional?1-D?TiO₂ nanobelts can provide effective transmission path for carriers to improve its radial transmission,which has a great advantage over other morphology TiO₂.Take advantage of 1-D morphology combined with 2-D nano morphology,to some extent,we can not only increase the catalyst carrier transmission rate but also can increase the contact area of catalyst and electrolyte,thus to improve the performance of catalysts.Therefore,this paper used TiO₂ nanobelts as matrix,constructed different structure of TiO₂ nanocomposite materials by selecting different compound phases.Then the prepared samples were characterized by XRD,SEM,TEM,UV-Vis,RamanandXPSanalysismethodstochecktheir electrocatalytic/photoelectrocatalytic performance and explore how morphology can affect its electrocatalytic/photoelectrocatalytic performance.The main research results are as follows:?1?TiO₂/SnS₂ heterojunction catalyst was prepared via a simple hydrothermal method using P25 as titanium source and Sn Cl₄·5H₂O as tin source.The influence of valence bond environment and exposed crystal facets of TiO₂/Sn S₂ for its OER performance has been studied and it turned out that these two factors can enhance its OER performance.Meanwhile,the morphology of the catalyst also plays a certain role in enhancing its OER performance.?2?The mutually independent crystal facet exposed Ti O₂ homojunction was successfully prepared by a simple hydrothermal method using P25/TBOT as titanium source.The Ti O₂ homojunction was constructed by growing TiO₂nanosheets through out the side facets of TiO₂ nanobelts under the crystal face induction effect.The length and width of the TiO₂ homojunction is several micrometers and around 400 nanometers,respectively.The TiO₂ homojunction structure is constructed by the same building blocks of nano-scale dimension,with the higher carrier transfer and lower electron-hole pair recombination rate at the interface compared to heterojunction,due to the little lattice mismatching and continuity of the chemical bonding and can enhance its PEC performance.Meanwhile,the morphology of homojunction plays an important role in their performance.Homojunction established via two components with different morphologies:1-D materials,like nanobelt,have the faster electrons transport ability compared to other morphology,2-D nanomaterials are always with higher specific surface area?BET?compared to that of 1-D nanobelts,and can increase the contact area with electrolyte and then improve photoelectrocatalytic performance.?3?TiO₂ NBs@TiO₂ NSs@Au composite catalyst was prepared through a photoreduction deposite method using TiO₂ homojunction as matrix,HAu Cl₄·4H₂O as the source of Au.The influence of the surface plasmon resonance effect?SPR?arising from the Au nanoparticles decorated on the surface of TiO₂ homojunction was detected.Then the influence of the amount of the loading of Au nanoparticles to the PEC performance was also studied by changing the quality ratios of HAu Cl₄·4H₂O and it turned out that Au nanoparticles do can enhance the PEC performance of catalysts by increasing the electrons transfer.