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首页> 外文期刊>RSC Advances >Charge carrier dynamics and photocatalytic behavior of TiO2 nanopowders submitted to hydrothermal or conventional heat treatment
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Charge carrier dynamics and photocatalytic behavior of TiO2 nanopowders submitted to hydrothermal or conventional heat treatment

机译：TiO2纳米粉末提交到水热处理或常规热处理的电荷载体动力学和光催化行为

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The sol–gel technique followed by conventional (TiO _(2) -1) and hydrothermal (TiO _(2) -2) thermal treatment was employed to prepare TiO _(2) -based photocatalysts with distinct particle sizes and crystalline structures. The as prepared metal oxides were evaluated as photocatalysts for gaseous HCHO degradation, methanol, and dye oxidation reactions. Additionally, metallic platinum was deposited on the TiO _(2) surfaces and H _(2) evolution measurements were performed. The photocatalytic activities were rationalized in terms of morphologic parameters along with the electron/hole dynamics obtained from transient absorption spectroscopy (TAS). TiO _(2) -2 exhibits smaller particle size, poorer crystallinity, and higher surface area than TiO _(2) -1. Moreover the hydrothermal treatment leads to formation of the metastable brookite phase, while TiO _(2) -1 exhibits only the anatase phase. TAS measurements show that the electron/hole recombination of TiO _(2) -2 is faster than that of the latter. Despite that, TiO _(2) -2 exhibits higher photonic efficiencies for photocatalytic oxidation reactions, which is attributed to its larger surface area that compensates for the decrease of the surface charge carrier concentration. For H _(2) evolution, it was found that the surface area has only a minor effect and the photocatalyst performance is controlled by the efficiency of the electron transfer to the platinum islands. This process is facilitated by the higher crystallinity of TiO _(2) -1, which exhibits higher photonic efficiency for H _(2) evolution than that observed for TiO _(2) -2. The results found here provide new insights into the correlations between thermal treatment conditions and photocatalytic activity and will be useful for the design of high performance photocatalysts.
机译：使用常规（TiO _（2）-1）和水热（TiO _（2）-2）热处理的溶胶 - 凝胶技术用于制备基于不同的颗粒尺寸和结晶结构的基于催化剂的TiO _（2）的光催化剂。作为对气态Hcho降解，甲醇和染料氧化反应的光催化剂评价如制备的金属氧化物。另外，将金属铂沉积在TiO _（2）表面上，并进行H _（2）进化测量。在形态学参数方面，光催化活性与从瞬态吸收光谱（TAS）获得的电子/空穴动力学合理化。 TiO _（2）-2表现出较小的粒度，较差的结晶度和高于TiO _（2）-1的表面积。此外，水热处理导致形成亚稳态Brookite相，而TiO _（2）-1仅表现出锐钛矿相。 TAS测量表明，TiO _（2）-2的电子/空穴重组比后者的电子/空穴重组更快。尽管如此，TiO_（2）-2表现出光催化氧化反应的较高光子效率，其归因于其较大的表面积，该表面积补偿表面电荷载流量的减小。对于H _（2）的进化，发现表面积仅具有微小的效果，并且通过电子转移到铂岛的效率来控制光催化剂性能。通过TiO _（2）-1的较高结晶度促进该方法，其表现出比对于TiO _（2）-2观察到的H _（2）展示的更高的光子效率。这里发现的结果为热处理条件和光催化活性之间的相关性提供了新的见解，并可用于高性能光催化剂的设计。

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