Zhong Yuanyuan, Zhang Xiuping, Xia Yangwen, Zhang Ling, Xu Qiao, Zhu Xiaodong, Feng Wei, Qin Qin
School of Mechanical Engineering, Chengdu University, Chengdu 610106, China.
Material Corrosion and Protection Key Laboratory of Sichuan Province, Zigong 643002, China.
Molecules. 2023 Nov 16;28(22):7626. doi: 10.3390/molecules28227626.
ZnTiO/TiO composite photocatalysts were synthesized via the sol-gel technique, and the impact of varying heat treatment temperatures (470, 570, 670 °C) on their crystalline arrangement, surface morphology, elemental composition, chemical state, specific surface area, optical characteristics, and photocatalytic efficacy was systematically investigated. The outcomes revealed that, as the temperature ascends, pure TiO undergoes a transition from anatase to rutile, ultimately forming a hybrid crystal structure at 670 °C. The incorporation of ZnTiO engenders a reduction in the TiO grain dimensions and retards the anatase-to-rutile phase transition. Consequently, the specimens manifest a composite constitution of anatase and ZnTiO. In contrast, for pure TiO, the specimen subjected to 670 °C annealing demonstrates superior photocatalytic performance due to its amalgamated crystal arrangement. The degradation efficacy of methylene blue (MB) aqueous solution attains 91% within a 60-min interval, with a calculated first-order reaction rate constant of 0.039 min. Interestingly, the ZnTiO/TiO composite photocatalysts exhibit diminished photocatalytic activity in comparison to pristine TiO across all three temperature variations. Elucidation of the photocatalytic mechanism underscores that ZnTiO coupling augments the generation of photogenerated charge carriers. Nonetheless, concurrently, it undermines the crystalline integrity of the composite, yielding an excess of amorphous constituents that impede the mobility of photoinduced carriers. This dual effect also fosters escalated recombination of photogenerated charges, culminating in diminished quantum efficiency and reduced photocatalytic performance.
通过溶胶 - 凝胶技术合成了ZnTiO/TiO复合光催化剂，并系统研究了不同热处理温度（470、570、670℃）对其晶体结构、表面形貌、元素组成、化学状态、比表面积、光学特性和光催化效率的影响。结果表明，随着温度升高，纯TiO从锐钛矿向金红石转变，最终在670℃形成混合晶体结构。ZnTiO的掺入使TiO晶粒尺寸减小，并延缓了锐钛矿向金红石的相变。因此，样品呈现出锐钛矿和ZnTiO的复合结构。相比之下，对于纯TiO，670℃退火的样品由于其混合晶体结构而表现出优异的光催化性能。亚甲基蓝（MB）水溶液在60分钟内的降解效率达到91%，计算得到的一级反应速率常数为0.039 min⁻¹。有趣的是，在所有三种温度变化下，ZnTiO/TiO复合光催化剂与原始TiO相比，光催化活性均降低。对光催化机理的阐释强调，ZnTiO耦合增加了光生电荷载流子的产生。然而，与此同时，它破坏了复合材料的晶体完整性，产生了过量的无定形成分，阻碍了光生载流子的迁移。这种双重效应还促进了光生电荷的复合增加，最终导致量子效率降低和光催化性能下降。
