Effect of Ag Co-catalyst on TiO2-Cu2O nanocomposites structure and apparent visible photocatalytic activity.
Effect of Ag Co-catalyst on TiO2-Cu2O nanocomposites structure and apparent visible photocatalytic activity.
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DOI：
10.1016/j.jenvman.2020.110175
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发表时间：
2020-04
影响因子：
8.7
通讯作者：
D. Nagy;Cong Chao;Bartosz Marzec;F. Nudelman;M. Ferrari;Xianfeng Fan
中科院分区：
文献类型：
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作者：
D. Nagy;Cong Chao;Bartosz Marzec;F. Nudelman;M. Ferrari;Xianfeng Fan
Cu_2O是一种常用的窄带隙半导体材料，但目前关于Ag共催化的TiO_2-Cu_2O纳米复合材料的报道较少。本文报道了一种简便的湿化学合成法制备TiO 2-Ag-Cu 2 O三元杂化纳米材料。独特的是，研究了银含量和银沉积步骤的合成顺序对可见脱色率的影响。采用XRD、SEM、TEM和漫反射光谱等手段对纳米结构的晶体结构、形貌、光吸收和暗吸收性能进行了表征。由于纳米复合材料的混合间接和直接性质，通过使用Tauc图和微分反射率模型来进行带隙估计。催化剂的暗吸附性能通常可以用伪二级动力学很好地近似，而TiO 2-Ag（5%）-Cu 2 O催化剂不能用标准模型描述，因为在前50 min内观察到延迟吸附行为。表观可见光活性遵循伪零级动力学。结果表明，TiO_2-Ag（3%）-Cu_2O催化剂具有最高的反应速率常数，约为100。是二元TiO 2-Cu 2 O催化剂的2倍。Ag沉积步骤的合成顺序显著改变了材料性质，这导致不同的暗吸收和表观可见光活性。
Although Cu2O is a commonly used narrow band gap semiconductor to fabricate visible response photocatalysts, up to date there are only a few reports on Ag co-catalysed TiO2–Cu2O nanocomposites. Herein we report a facile wet chemical synthesis approach to prepare TiO2–Ag–Cu2O ternary hybrid nanomaterials. Uniquely, both the effect of Ag content and the synthesis sequence of Ag deposition step was investigated on the visible decoloration rate. The crystal structure, morphology, optical and dark adsorption properties of the nanostructures were characterized by XRD, SEM, TEM and diffuse reflectance, respectively. Due to the mixed indirect and direct nature of the nanocomposites, the band gap estimation was performed by using both Tauc plot and differential reflectance model. The dark adsorption properties of catalysts could be typically well-approximated by pseudo-second order kinetics, while TiO2–Ag(5%)-Cu2O catalyst cannot be described by standard models due to a delayed adsorption behaviour observed in the first 50 min. The apparent visible activities followed pseudo-zero order kinetics. It was found that TiO2–Ag(3%)-Cu2O catalyst exhibited the highest rate constant which was ca. two times as high as that of the binary TiO2–Cu2O catalyst. The synthesis sequence of the Ag deposition step significantly altered the material properties which resulted in different dark adsorption and apparent visible activities.