The fast recombination of photogenerated electrons and holes in the pure TiO2 leads to a low photocatalytic efficiency in hydrogen generation or solar energy conversion. Noble metal nanoparticles have been used to combine with TiO2 for effective photocatalysis. Herein, Au@Ag@TiO2 nanorods (NRs) with core–shell structure have been prepared by hydrolysis the precursor of titanium in acid environment. UV light–driven H2 generation rate of Au@Ag@TiO2 samples demonstrated 14 times enhancement compared to P25 TiO2 at the same experimental conditions. The improved photocatalytic performance was due to the charge transfer from the conduction band of excited TiO2 to Au@Ag NRs leading to effective separation of electron–hole pairs. This mechanism has been proved by transient absorption spectroscopy and photo-electrochemical (PEC) measurements. The time resolved photocurrents of P25 TiO2 NPs is ~ 13 times higher that of Au@Ag@TiO2, indicating that a fraction of the photogenerated electrons of TiO2 driven by UV light transfer to Au@Ag nanocores instead of transporting entirely to the ITO substrates. The ultrafast transient absorption and pump-probe measurements demonstrated a faster decay in Au@Ag@TiO2 NRs compared to pure TiO2 system, indicating that the photogenerated electron–hole recombination in TiO2 is substantially suppressed by Au@Ag@TiO2 NRs attributed to the effective trapping of the photogenerated electrons by the Au@Ag cores. Au@Ag@TiO2 nanocomposites with core-shell structure have been prepared and its UV light–driven H2 generation rate has been demonstrated 14 times enhancement compared to P25 TiO2 at the same experimental conditions. The improved photocatalytic performance was due to the charge transfer, which has been proved by photocurrent measurement and the ultrafast transient absorption and pump-probe measurements.

中文翻译：

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了解金属@TiO2 核壳纳米棒在光催化制氢中的载流子动力学

纯 TiO2 中光生电子和空穴的快速复合导致制氢或太阳能转换的光催化效率低。贵金属纳米粒子已被用于与二氧化钛结合以实现有效的光催化。在此，通过在酸性环境中水解钛的前驱体，制备了具有核壳结构的 Au@Ag@TiO2 纳米棒（NRs）。在相同的实验条件下，与 P25 TiO2 相比，紫外光驱动的 Au@Ag@TiO2 样品的 H2 生成率提高了 14 倍。光催化性能的提高是由于电荷从激发态 TiO2 的导带转移到 Au@Ag NRs 导致电子-空穴对的有效分离。这种机制已通过瞬态吸收光谱和光电化学 (PEC) 测量得到证实。P25 TiO2 NPs 的时间分辨光电流比 Au@Ag@TiO2 高约 13 倍，表明由紫外光驱动的 TiO2 光生电子的一部分转移到 Au@Ag 纳米核，而不是完全转移到 ITO 基板。超快瞬态吸收和泵浦探针测量表明，与纯 TiO2 体系相比，Au@Ag@TiO2 NRs 的衰减更快，表明 TiO2 中的光生电子 - 空穴复合被 Au@Ag@TiO2 NRs 显着抑制，归因于有效的Au@Ag 核捕获光生电子。已制备出具有核壳结构的 Au@Ag@TiO2 纳米复合材料，在相同的实验条件下，与 P25 TiO2 相比，其紫外光驱动的 H2 生成率提高了 14 倍。