Abstract This study reveals the impact of different amount of Ag photo-deposited on the surface of TiO2 for improved oxidation of p-nitrobenzaldehyde (p-NBAL) and reduction of p-nitrobenzoic acid (p-NBA) under UV or sunlight irradiation. Due to formation of Ag (1–3 wt%) nanodeposits over TiO2, the hydrodynamic size of Ag-TiO2 composite is increased by 1.5, 1.8 and 2.7 times relative to bare P25-TiO2 (~252 nm). The intensity of optical/surface absorption (463 nm) band and emission of various Ag-TiO2 hybrid composites varied significantly as function of the amount of Ag loadings. TEM analysis of 2 wt% Ag loaded TiO2 further evidenced the growth of Ag nanoparticles (~10 nm) on the support. It was found that the oxidation of p-NBAL and reduction of p-NBA by 2 wt% Ag-TiO2 under sunlight irradiation occurred quite efficiently whereas bare TiO2 showed negligible activity under same reaction conditions. The plasmonic interactions within Ag and TiO2 enhanced visible light sensitivity which was evident from higher reduction efficiency (2.2 times) of p-NBA under solar light than UV exposure. Thus, different amount of Ag co-catalyst and irradiation source have influenced both the activity and selectivity for oxidation and reduction reactions.

中文翻译：

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紫外/阳光下等离子体Ag-TiO2纳米复合材料的光诱导氧化和还原

摘要 本研究揭示了在 TiO2 表面光沉积不同量的 Ag 对改善对硝基苯甲醛 (p-NBAL) 氧化和在紫外线或阳光照射下对硝基苯甲酸 (p-NBA) 还原的影响。由于在 TiO2 上形成了 Ag（1-3 wt%）纳米沉积物，Ag-TiO2 复合材料的流体力学尺寸相对于裸 P25-TiO2（~252 nm）增加了 1.5、1.8 和 2.7 倍。各种 Ag-TiO2 混合复合材料的光学/表面吸收 (463 nm) 带和发射强度随 Ag 负载量的不同而显着变化。载有 2 wt% Ag 的 TiO2 的 TEM 分析进一步证明了 Ag 纳米粒子 (~10 nm) 在载体上的生长。发现在阳光照射下 p-NBAL 的氧化和 p-NBA 被 2 wt% Ag-TiO2 的还原非常有效，而在相同的反应条件下，裸 TiO2 的活性可以忽略不计。Ag 和 TiO2 内的等离子体相互作用增强了可见光敏感性，这从 p-NBA 在太阳光下的还原效率（2.2 倍）比紫外线照射更高。因此，不同量的银助催化剂和辐照源影响了氧化和还原反应的活性和选择性。