Microwave-assisted solvothermal synthesis of novel hierarchical BiOI/rGO composites for efficient photocatalytic degardation of organic pollutants

Micro-mesoporous anatase TiO2 nanorods with high specific surface area possessing enhanced adsorption ability and photocatalytic activity

Abstract Microfluidics is an emerging branch of science that has significant applications in various fields. In this review paper, after a brief introduction to the concept of photocatalysis, nanoparticle preparation methods and film formation techniques have been studied. Nanoparticle synthesis in microfluidic systems and microreactor types for on-chip photocatalyst synthesis and challenges of nanoparticles handling in microsystems have been reviewed. To resolve particle polydispersity and microchannel clogging, a good suggestion can be the use of droplet-based microreactors. The configurative designs for the microfluidic reactor with immobilized photocatalysts, their applications, and their challenges have been comprehensively addressed. The three main challenges ahead the immobilized photocatalytic microfluidic reactors are optimal light distribution, prevention of the recombination of photogenerated electrons and holes, and improved mass transfer. Internal light-emitting diodes with a waveguide can resolve the number one challenge of photocatalysis application in optofluidic reactors, that is, light distribution.

A review on the design and development of photocatalyst synthesis and application in microfluidic reactors: challenges and opportunities

Solar water splitting with nanostructured hematite: The role of annealing-temperature

Pristine and Co-doped TiO2 mesocrystals have been synthesized via a simple sol-gel method and their antimicrobial activity has been investigated. The antimicrobial performance was evaluated in terms of zone of inhibition, minimum inhibitory concentration (MIC), antibiofilm activity, and effect of UV illumination in liquid media. The Co-doped TiO2 mesocrystals showed very promising MIC of 0.390 μg/mL and 0.781 μg/mL for P. mirabilis and P. mirabilis, respectively. Additionally, the material showed an MIC of 12.5 μg/mL against C. albicans, suggesting its use as antifungal agent. Upon the addition of 10.0 µg/mL of Co-doped TiO2 mesocrystals, the biofilm inhibition% reaches 84.43% for P. aeruginosa, 78.58% for P. mirabilis, and 77.81% for S. typhi, which can be ascribed to the created active oxygen species that decompose the tested microbial cells upon illumination. Thus the fabricated Co-doped TiO2 mesocrystals exhibit sufficient antimicrobial features under visible light, qualifying them for use as antimicrobial agents against pathogenic bacteria and fungi and subsequently inhibit their hazardous effects.

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Superior visible light antimicrobial performance of facet engineered cobalt doped TiO2 mesocrystals in pathogenic bacterium and fungi.

Phase-pure anatase titanium dioxide (A-TiO 2 ) with high thermal stability is synthesized by a microwave-assisted hydrothermal (MAH) method. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N 2 adsorption–desorption isotherms, and photoluminescence spectra (PL) analysis. The photo-electrochemical responses are examined via linear sweep voltammetry (LSV), intensity-modulated photocurrent spectroscopy (IMPS), and intensity-modulated photovoltage spectroscopy (IMVS). The photocatalytic activity of TiO 2 nanoparticles (NPs) has been confirmed through the methylene blue (MB) de-colorization under the simulated sunlight. The results show that the as-prepared TiO 2 nanocrystals possess thermal stability for the anatase-to-rutile phase transformation up to 900 °C. The phase-pure A-TiO 2 annealed at 800 °C exhibits a much higher de-colorization rate than the commercially available TiO 2 (Degussa P25) powders. The higher photocatalytic activity of this sample is due to its enhanced crystallinity, leading to a lower rate of electron/hole pair recombination and a larger photocurrent density in comparison with all other samples and P25. The sample annealed at 900 °C shows the highest specific activity on MB de-colorization, demonstrating the importance of thermal stability and crystalline phase.

Highly active and thermo-stable anatase TiO2 photocatalysts synthesized by a microwave-assisted hydrothermal method

This work demonstrates how to set efficiency benchmarks in photo-electrochemical measurements for solar water splitting with assistance of voltage biases. We modify the applied bias photon-to-current efficiency to circumvent the existing limitations for precisely estimating the energy transformation efficiency under valid conditions. The light sources, surface area of counter electrodes, and oxygen content in electrolytes, and photo-anode materials are changed to investigate their impact on the energy transformation efficiency. This work clarifies that a larger counter electrode surface area results in the enhancement of the oxygen reduction reaction, reducing the applied bias voltage but also reducing the hydrogen generation rate. Furthermore, positive potential biases on the photo-anode and removal of dissolved oxygen molecules in the electrolyte are effective to promote the hydrogen generation rate because of efficient electron/hole separation and the ORR elimination. Due to the high photocurrent generated by the ultraviolet light source, the consumption of photocurrents by the ORR is generally negligible. Therefore, a balance between photocurrent and applied potential bias on the photo-electrochemical cell is proposed to achieve the desired energy transformation efficiency.

How to achieve the desired performance of solar water splitting with voltage biases

With data storage capacity increasing, more memory cell stacks for three-dimensional NAND (3D NAND) devices are developed. When stacking more thin-film layers, the capability to form uniform high aspect ratio (HAR) structures becomes a key 3D NAND process step. Therefore, in 3D NAND manufacturing, etch process control is especially important. Etch processes generate HAR structures and defects are usually buried in the deep trenches or holes, which become inspection challenges. Defect control is important for semiconductor manufacturing to ensure device quality. In this study, a high landing energy (HiLE) e-beam defect inspection system with a wide landing energy operation range is utilized to compare scanning electron microscopy (SEM) images of different landing energy to get the best signal for defects of interest (DOI) that are buried in the deep vertical channel (VC) holes. A landing energy of 30KeV was determined to provide best DOI imaging. In addition, to reduce the burden of manual defect classification (MDC) and improve traditional algorithm limitations, a deep learning (DL)-based algorithm methodology is implemented that successfully demonstrates detection of DOI at ~6 μm depth within the VC holes of a 96-layer 3D NAND device, while also achieving auto defect classification (ADC) with >90% purity by each VC row.

Yen-Chun Chuan Sun

Papers

Highly active and thermo-stable anatase TiO2 photocatalysts synthesized by a microwave-assisted hydrothermal method

How to achieve the desired performance of solar water splitting with voltage biases

3D NAND vertical channel defect inspection and classification solution on a DL-based e-beam system : DI : Defect Inspection and Reduction