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Hierarchically porous silicon with significantly improved photocatalytic oxidation capability for phenol degradation

Paper ID Volume ID Publish Year Pages File Format Full-Text
46250 46435 2013 7 PDF Available
Title
Hierarchically porous silicon with significantly improved photocatalytic oxidation capability for phenol degradation
Abstract

•Oxidation capability of prepared porous silicon is elevated significantly due to quantum confinement effect.•Hierarchically porous silicon as a cathode displays good electrochemical stability.•Porous silicon can decompose phenol via oxidation approach under visible light irradiation for the first time.

In this work, hierarchically porous silicon was fabricated through electro-assisted chemical etching using a silicon wafer as a substrate. Pores with an average diameter of ca. 1200 nm (macropores) were observed and a large number of nanopores with a diameter of less than 5 nm were uniformly distributed over the surface of the macropore, forming the hierarchically porous silicon with nanopores in macropores structure (NP-MPSi). UV–vis diffuse reflection measurements indicated that NP-MPSi has a bandgap of 2.12 eV, which is 1.0 eV higher than that of the original silicon wafer because of the quantum confinement effect caused by the nanopores. Mott–Schottky experiments further demonstrated that the increase in bandgap of NP-MPSi arises from a positive shift of the valence band potential, which improves its capability for photocatalytic oxidation. NP-MPSi exhibited higher photoelectrochemical stability than macroporous silicon (MPSi), a comparison sample lacking nanopores. Using phenol as an example, photocatalytic experiments under irradiation with a Xe lamp demonstrated that the kinetic constants of phenol degradation and total organic carbon removal using NP-MPSi were nearly 3.5 and 8.0 times larger, respectively, than those using MPSi. This unique porous silicon material is therefore an attractive photocatalyst for environmental applications.

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Keywords
Porous silicon; Quantum confinement effect; Photocatalytic oxidation; Stability
First Page Preview
Hierarchically porous silicon with significantly improved photocatalytic oxidation capability for phenol degradation
Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volumes 138–139, 17 July 2013, Pages 427–433
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis