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Type: Journal article
Title: Engineering the slow photon effect in photoactive nanoporous anodic alumina gradient-index filters for photocatalysis
Author: Lim, S.
Law, C.
Markovic, M.
Kirby, J.
Abell, A.
Santos, A.
Citation: ACS Applied Materials and Interfaces, 2018; 10(28):24124-24136
Publisher: American Chemical Society
Issue Date: 2018
ISSN: 1944-8244
Statement of
Siew Yee Lim, Cheryl Suwen Law, Marijana Markovic, Jason K. Kirby, Andrew D. Abell, and Abel Santos
Abstract: In this study, we explore for the first time the capabilities of nanoporous anodic alumina gradient-index filters (NAA-GIFs) functionalized with titanium dioxide (TiO₂) photoactive layers to enhance photon-to-electron conversion rates and improve the efficiency of photocatalytic reactions by “slow photon” effect. A set of NAA-GIFs was fabricated by sinusoidal pulse anodization, in which a systematic modification of various anodization parameters (i.e., pore widening time, anodization period, and anodization time) enables the fine-tuning of the photonic stopband (PSB) of these nanoporous photonic crystals (PCs) across the spectral regions. The surface of NAA-GIFs was chemically modified with photoactive layers of TiO₂ to create a composite photoactive material with precisely engineered optical properties. The photocatalytic performance of TiO₂-functionalized NAA-GIFs was assessed by studying the photodegradation of three model organic dyes (i.e., methyl orange, Rhodamine B, and methylene blue) with well-defined absorption bands across different spectral regions under simulated irradiation conditions. Our study demonstrates that when the edges of characteristic PSB of TiO₂-modified NAA-GIFs are completely or partially aligned with the absorption band of the organic dyes, the photodegradation rate is enhanced due to “slow photon” effect. A rational design of the photocatalyst material with respect to the organic dye is demonstrated to be optimal to speed up photocatalytic reactions by an efficient management of photons from high-irradiance spectral regions. This provides new opportunities to develop high-performing photocatalytic materials for efficient photocatalysis with broad applicability.
Keywords: Nanoporous anodic alumina; photonic crystals; slow photon effect; surface-modification; photocatalysis
Description: Published: June 25, 2018
Rights: © 2018 American Chemical Society
DOI: 10.1021/acsami.8b05946
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