Urso Mario, Bruno Luca, Dattilo Sandro, Carroccio Sabrina C, Mirabella Salvo
Dipartimento di Fisica e Astronomia "Ettore Majorana", Università degli Studi di Catania, via S. Sofia 64, Catania 95123, Italy.
CNR-IMM, via S. Sofia 64, Catania 95123, Italy.
ACS Appl Mater Interfaces. 2024 Jan 10;16(1):1293-1307. doi: 10.1021/acsami.3c13470. Epub 2023 Dec 22.
Light-powered micro- and nanomotors based on photocatalytic semiconductors convert light into mechanical energy, allowing self-propulsion and various functions. Despite recent progress, the ongoing quest to enhance their speed remains crucial, as it holds the potential for further accelerating mass transfer-limited chemical reactions and physical processes. This study focuses on multilayered MXene-derived metal-TiO micromotors with different metal materials to investigate the impact of electronic properties of the metal-semiconductor junction, such as energy band bending and built-in electric field, on self-propulsion. By asymmetrically depositing Au or Ag layers on thermally annealed TiCT MXene microparticles using sputtering, Janus structures are formed with Schottky junctions at the metal-semiconductor interface. Under UV light irradiation, Au-TiO micromotors show higher self-propulsion velocities due to the stronger built-in electric field, enabling efficient photogenerated charge carrier separation within the semiconductor and higher hole accumulation beneath the Au layer. On the contrary, in 0.1 wt % HO, Ag-TiO micromotors reach higher velocities both in the presence and absence of UV light irradiation, owing to the superior catalytic properties of Ag in HO decomposition. Due to the widespread use of plastics and polymers, and the consequent occurrence of nano/microplastics and polymeric waste in water, Au-TiO micromotors were applied in water remediation to break down polyethylene glycol (PEG) chains, which were used as a model for polymeric pollutants in water. These findings reveal the interplay between electronic properties and catalytic activity in metal-semiconductor junctions, offering insights into the future design of powerful light-driven micro- and nanomotors with promising implications for water treatment and photocatalysis applications.
基于光催化半导体的光驱动微纳马达将光转化为机械能，实现自我推进并具备多种功能。尽管近期已取得进展，但持续追求提高其速度仍然至关重要，因为这有可能进一步加速受传质限制的化学反应和物理过程。本研究聚焦于具有不同金属材料的多层MXene衍生的金属 - TiO微马达，以探究金属 - 半导体结的电子性质，如能带弯曲和内建电场，对自我推进的影响。通过使用溅射在热退火的TiCT MXene微粒上不对称沉积Au或Ag层，形成了在金属 - 半导体界面处具有肖特基结的Janus结构。在紫外光照射下，由于内建电场更强，Au - TiO微马达显示出更高的自我推进速度，这使得半导体内部的光生电荷载流子能够有效分离，并且在Au层下方有更高的空穴积累。相反，在0.1 wt%的H₂O₂中，由于Ag在H₂O₂分解方面具有优异的催化性能，Ag - TiO微马达在有无紫外光照射的情况下都能达到更高的速度。由于塑料和聚合物的广泛使用，导致水中出现纳米/微塑料和聚合物废物，Au - TiO微马达被应用于水修复以分解聚乙二醇（PEG）链，PEG链被用作水中聚合物污染物的模型。这些发现揭示了金属 - 半导体结中电子性质与催化活性之间的相互作用，为未来设计强大的光驱动微纳马达提供了见解，对水处理和光催化应用具有潜在意义。
