Less is more: Enhancement of photocatalytic activity of g-C3N4 nanosheets by site-selective atomic layer deposition of TiO2
Less is more: Enhancement of photocatalytic activity of g-C3N4 nanosheets by site-selective atomic layer deposition of TiO2
复制标题
少即是多：通过 TiO2 的位点选择性原子层沉积增强 g-C3N4 纳米片的光催化活性
DOI：
10.1016/j.apsusc.2019.07.131
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发表时间：
2019-11-15
影响因子：
6.7
通讯作者：
Yang, Yang
中科院分区：
文献类型：
--
作者：
Lv, Peng;Zhao, Chongyang;Yang, Yang
采用ALD技术制备了零维/二维(0D/2D)TiO2光催化剂/g-C3N4异质结光催化剂。在g-C3N4纳米片上选择性地生长了纳米TiO2光催化剂，表面修饰诱导了复合光催化剂的能带工程。因此，光催化剂的氧化还原性能得到了微调。在可见光下，由于只有g-C3N4被激发，在优化的界面结构中，二氧化钛起到了电子传递通道的作用。它们有效地抑制了复合，促进了光生电荷的转移，提高了光催化活性。当这两个组分在紫外可见光下被激发时，这些n-n型半导体异质结上导带位置的动态平衡导致了电荷复合速率的增加，从而降低了析氢反应的活性。但这些复合光催化剂对有机污染物的光催化降解活性有所提高，这是由于TiO2Vb上的光生空穴能够促进具有较强氧化潜力的有机污染物的氧化。此外，沉积循环次数有限的TiO2/g-C3N4光催化剂在可见光下具有最佳的光催化活性。而在g-C3N4上沉积过多的TiO2/g-C3N4导致了连续的薄膜，增加了TiO2膜的厚度，导致了反应活性的衰减。我们验证了这种二氧化钛/g-C3N4光催化剂具有较小的负载量，但光催化活性得到了较大的提高。
Zero-dimensional/two-dimensional (0D/2D) TiO2/g-C3N4 heterostructural photocatalysts were fabricated via ALD technique. TiO2 nanoparticles were "site-selectively grown" on g-C3N4 nanosheets and the surface modification induced band engineering of the composite photocatalysts. Thus, the redox properties of the photocatalysts were fine tuned. Under visible light, since only g-C3N4 was excited, TiO2 was acting as the electron transport channel in the optimized interfacial structures. They effectively suppressed the recombination and facilitated the transfer of photogenerated charges, improving the photocatalytic activity. When both the components were excited under UV-vis light, the dynamic equilibrium of the conduction band positions on these n-n type semiconductor heterojunctions led to the increased recombination rate of charges, decreasing the reactivity for H-2 evolution. However, the photocatalytic degradation of organic pollutants by these composite photocatalysts exhibited enhanced activities, resulting from the photogenerated holes on VB of TiO2 which could promote oxidation of organic pollutants with strong oxidation potentials. Furthermore, TiO2/g-C3N4 photocatalysts with limited numbers of deposition cycles exhibited optimal photocatalytic activity under visible light. In contrast, excessive deposition cycles on g-C3N4 for TiO2/g-C3N4 led to continuous film and increased thickness of TiO2, resulting in the attenuation of the reactivity. We verified this TiO2/g-C3N4 photocatalysts with less massloading, but more enhanced photocatalytic activity.