Metallic nanohole arrays exciting both surface plasmon polariton (SPP) and localized surface plasmon resonance (LSPR) in a single thin film have sparked considerable interest in the field of plasmonics. To exert their full potential for the generation of hot electrons in visible light, we bury an Au nanohole array (AuNHA) under a thin TiO2 layer and decorate Pt nanoparticles randomly on the surface to form the Pt/TiO2/AuNHA nanocomposite. As compared to the Pt/TiO2/Au film, the Pt/TiO2/AuNHA sample with a 90 nm hole diameter shows an enhancement of 4.1 folds in photocurrent density, 14.7 folds in the peak of incident photon-to-current conversion efficiency, and 9.4 folds in the degradation of methyl orange. Moreover, numerical simulations are conducted to analyze the contributions of SPP and LSPR effects at different wavelengths. This work is the first study of AuNHAs fully covered by a thin TiO2 film and provides a unique design of photoelectrodes for solar photocatalysis applications.

Plasmonic hot-carrier generation can be harnessed by the strong coupling of the cavity mode, the LSPR mode, and the gap surface plasmon polariton.

This work reports a microfluidic reactor that utilizes gold nanoparticles (AuNPs) for the highly efficient photocatalytic degradation of organic pollutants under visible light. The bottom of microchamber has a TiO 2 film covering a layer of AuNPs (namely, TiO 2 /AuNP film) deposited on the F-doped SnO 2 (FTO) substrate. The rough surface of FTO helps to increase the surface area and the AuNPs enables the strong absorption of visible light to excite electron/hole pairs, which are then transferred to the TiO 2 film for photodegradation. The TiO 2 film also isolates the AuNPs from the solution to avoid detachment and photocorrosion. Experiments show that the TiO 2 /AuNP film has a strong absorption over 400-800 nm and enhances the reaction rate constant by 13 times with respect to the bare TiO 2 film for the photodegradation of methylene blue. In addition, the TiO 2 /AuNP microreactor exhibits a negligible reduction of photoactivity after five cycles of repeated tests, which verifies the protective function of the TiO 2 layer. This plasmonic photocatalytic microreactor draws the strengths of microfluidics and plasmonics, and may find potential applications in continuous photocatalytic water treatment and photosynthesis. The fabrication of the microreactor uses manual operation and requires no photolithography, making it simple, easy, and of low cost for real laboratory and field tests.2 of 11 resonance (LSPR) due to the collective oscillation of free electrons in response to the excitation of irradiant light. The LSPR effect can drastically enhance the visible response of TiO 2 photocatalysis for solar energy capture, environmental redemption, and selective organic photosynthesis [5,7,9,10]. Moreover, the direct physical contact of the noble metal NPs and the TiO 2 photocatalysts would form a Schottky junction to suppress the recombination of electron-hole pairs [8,11].Typical photodegradation systems involve the suspension of TiO 2 nanopowders in an aqueous solution of a bulky container. With the stirring, the TiO 2 nanopowders have full contact with the dissolved organic pollutants, resulting in a large specific surface area (SSA, defined as the total surface area per unit of mass) and high photodegradation efficiency. However, the suspended TiO 2 nanopowders absorb and scatter light, causing rapid decay, and thus an uneven distribution of the irradiant light. What is more problematic is the requirement of post processing, namely the nanopowders have to be separated from the solution after the reaction [12][13][14]. To avoid these problems, immobilized systems have been developed to fix the TiO 2 photocatalysts on a support, but they tend to have a small SSA and low efficiency [15].Microfluidic reactors have attracted much attention and have been proposed to tackle the drawbacks of photocatalytic processes [14,[16][17][18][19][20]. They inherit many advantages from microfluidics technology, such as small dimensions, high surface-to-volume (S/V) ratio, easy control of flow rates, short molecular diffusion distance,...

Solar water splitting by photoelectrochemical (PEC) reactions is promising for hydrogen production. The gold nanoparticles (AuNPs) are often applied to promote the visible response of wideband photocatalysts. However, in a typical TiO2/AuNPs structure, the opposite transfer direction of excited electrons between AuNPs and TiO2 under visible light and UV light severely limits the solar PEC performance. Here we present a unique Pt/TiO2/Cu2O/NiO/AuNPs photocathode, in which the NiO hole transport layer (HTL) is inserted between AuNPs and Cu2O to achieve unidirectional transport of charge carriers and prominent plasmon-induced resonance energy transfer (PIRET) between AuNPs and Cu2O. The measured applied bias photon-to-current efficiency and the hydrogen production rate under AM 1.5G illumination can reach 1.5% and 16.4 μmol·cm-2·h-1, respectively. This work is original in using the NiO film as the PIRET spacer and provides a promising photoelectrode for energy-efficient solar water splitting.

We have developed and validated a deep learning-based real-time high-quality (HQ) multi-parametric (Mp) 4D-MRI technique. A dual-supervised downsampling-invariant deformable registration (D3R) model was trained on retrospectively downsampled 4D-MRI with 100 radial spokes in the k-space. The deformations obtained from the downsampled 4D-MRI were applied to 3D-MRI to reconstruct HQ Mp 4D-MRI. The D3R model provides accurate and stable registration performance at up to 500 times downsampling, and the HQ Mp 4D-MRI shows significantly improved quality with sub-voxel level motion accuracy. This technique provides HQ Mp 4D-MRI within 500 ms and holds great potential in online tumor tracking in MR-guided radiotherapy.