Controlled Synthesis And Heterogeneous Catalytic Performance Of High-Quality γ-Ga₂O₃ Nanoplates

Energy and environment are the topics of common concern for human society,sulfur compounds in petroleum will not only reduce the quality of oil products and corrode refinery equipments,but also cause serious pollution to environment.In order to solve these problems,achieving desulfuration of oil products is the key.As we all know,the controlled synthesis,crystal structure characterization and catalytic performance of gallium oxide(Ga2O3)functional nanomaterials has become one of the focuses of current researchers.The metastable γ-Ga2O3 is the most important,but its synthesis conditions are more harsh,which has caused many scholars’ interests and attentions.According to our knowledge,γ-Ga2O3 materials with different morphologies and dimensions have been reported one after another,including one-dimensional tube/line/rod structure,and three-dimensional flower/ball structure,but two-dimensional γ-Ga2O3 is rarely been reported due to the high degree of self-assembly tendency.This paper mainly contains two aspects:1)Controlled synthesis of high-quality two-dimensional γ-Ga2O3 hexagonal nanoplates based on multiple interaction model;2)Investigation of heterogeneous catalytic performance of Ga2O3 materials with different phases and morphologies for thiophenes.The first part mainly includes the following contents:in aqueous solution,the high quality γ-Ga2O3 hexagonal nanoplates was successfully synthesized based on the competitive/cooperative interaction model between multiple equilibria(including precipitation equilibrium,coordination equilibrium and two kinds of binding equilibria).These nanoplates display a perfect structure of single crystal,a smooth surface,a uniform size distribution,excellent monodispersity,and a rather high two-dimensional structural stability.This method is novel,green,simple,efficient and with a high yield,avoiding long reaction time and high temperature,without the use of organic solvents and toxic reagents.First,the potassium oxalate reacts with gallium ions in aqueous solution to form the complex tris(oxalato)gallium(Ⅲ)precursor,thereby inhibiting the gallium ions hydrolyze into gallium oxide hydroxide(GaOOH)and results in the direct production of γ-Ga2O3.Besides,the double binding effects of polyvinylpyrrolidone on the gallium ions and the complex reduce the formation and decomposition rate of tris(oxalato)gallium(Ⅲ),ultimately achieving the dimensional control of γ-Ga2O3 to obtain two-dimensional γ-Ga2O3 nanoplates.This paper also discusses the nature and concentration of ligand/host,pH,reaction time and temperature on the synthesis of two dimensional γ-Ga2O3 nanoplates,elucidates the disassemble mechanism based on multiple interactions model.The second part mainly includes the following contents:we evaluate the catalytic activities of y-Ga2O3 nanoplates,γ-Ga2O3 microflowers,β-Ga2O3 nanoplates,andβ-Ga2O3 microflowers for thiophene and its analogs,propose a possible catalytic mechanism of Ga2O3.We find that γ-Ga2O3 nanoplates exhibite generally higher catalytic oxidation activities for different types of thiophene analogs,and still show comparable catalytic efficiency to the fresh catalyst after 5 cycles,and does not require high temperature or pressure,without the use of any support,cocatalyst and phase transfer reagent,which means that two-dimensional γ-Ga2O3 nanocatalysts have promising application prospects in industrial desulfurization.