Open AccessPhotonic crystal light trapping for photocatalysis
Author(s) -
Xiwen Zhang,
Sajeev John
Publication year - 2021
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.427218
Subject(s) - photocatalysis , materials science , photonic crystal , visible spectrum , optoelectronics , optics , nanorod , nanotechnology , physics , chemistry , biochemistry , catalysis
The Achilles heel of wide-band photocatalysts such as TiO 2 is the insufficient photogeneration in the visible range under sunlight. This has been a longstanding impediment to large-scale, real-world deployment of titania-based photocatalysis applications. Instead of traditional band engineering through heavy-doping, we suggest enhancing photocatalytic efficiency of lightly-doped TiO 2 using photonic crystal (PC) structures. This strongly increases solar photogeneration through novel wave-interference-based light trapping. Four photocatalyst structures - simple cubic woodpile (wdp), square lattice nanorod (nrPC), slanted conical-pore (scPore), and face-centered cubic inverse opal (invop) - are optimized and compared for light harvesting in the sub- and above-gap (282 to 550 nm) regions of weakly absorbing TiO 2 , with the imaginary part of the dielectric constant 0.01 in the visible range. The optimized lattice constants for the first three, and opal center-to-center distance for invop, are ∼300 - 350 nm. For fixed PC thickness, the ranking of visible light harvesting capability is: scPore > wdp ∼ nrPC > invop. The scPore PC deposited on highly reflective substrate is ideal for photocatalysis given its combination of enhanced light trapping and superior charge transport.