Recent Developments in Heterogeneous Photocatalysts with Near-Infrared Response

Photocatalytic technology has been considered as an efficient protocol to drive chemical reactions in a sustainable and green way. With the assistance of semiconductor-based materials, heterogeneous photocatalysis converts solar energy directly into chemical energy that can be readily stored. It has been employed in several fields including CO2 reduction, H2O splitting, and organic synthesis. Given that near-infrared (NIR) light occupies 47% of sunlight, photocatalytic systems with a NIR response are gaining more and more attention. To enhance the solar-to-chemical conversion efficiency, precise regulation of the symmetric/asymmetric nanostructures and band structures of NIR-response photocatalysts is indispensable. Under the irradiation of NIR light, the symmetric nano-morphologies (e.g., rod-like core-shell shape), asymmetric electronic structures (e.g., defect levels in band gap) and asymmetric heterojunctions (e.g., PN junctions, semiconductor-metal or semiconductor-dye composites) of designed photocatalytic systems play key roles in promoting the light absorption, the separation of electron/hole pairs, the transport of charge carriers to the surface, or the rate of surface photocatalytic reactions. This review will comprehensively analyze the four main synthesis protocols for the fabrication of NIR-response photocatalysts with improved reaction performance. The design methods involve bandgap engineering for the direct utilization of NIR photoenergy, the up-conversion of NIR light into ultraviolet/visible light, and the photothermal effect by converting NIR photons into local heat. Additionally, challenges and perspectives for the further development of heterogeneous photocatalysts with NIR response are also discussed based on their potential applications.

Symmetrically Controlled Design of Twin Alumina-Co Composite Thin Films

Self-assembled dual-working electrode electrolytic cells were designed to produce twin alumina-Co composite films with highly symmetrical microstructures using a deflected electric field-assisted alternating current electrodeposition method. The results show that the deposition current density, microstructure, and optical and magnetic properties of the twin composite films exhibit a high degree of symmetry. The distribution of magnetic Co particles in the alumina nanopores can be changed by adjusting the magnitude of the deflected electric field, resulting in a synchronous symmetrical change in the microstructure of the composite films, which enables the fine-tuning of the magneto-optical properties of the twin alumina-Co composite films at the microscopic scale. The current density distribution on the surface of the twin composite films along the direction of the deflected electric field was quantitatively analyzed by theoretical calculations and numerical simulations. The results show that the deposition current density gradually increases from 0.024 A/m2 in region C to 0.056 A/m2 in region A at 6 V deflection voltage. The saturation magnetization intensity gradually increases along the radial direction, which is 118, 130, and 150 kA/m, respectively

Photocatalytic activation of TiO2-functionalized anodic aluminium oxide for electroless copper deposition

TiO2/AAO allows for a spatial photodeposition of copper seeds under UV illumination through a photomask, which along with its improved chemical stability allows for the additive deposition of conductive Cu patterns in an alkaline electroless Cu bath.