A light–heat synergism in the sub-bandgap photocatalytic response of pristine TiO₂: a study of in situ diffusion reflectance and conductance

Abstract

The sub-bandgap light-heat synergism induced electronic transition and their role in photocatalysis were revealed by means of in situ diffusion reflectances and (photo) conductances.

Fermi-level shift, electron separation, and plasmon resonance change in Ag nanoparticle-decorated TiO2 under UV light illumination

“…The of anatase TiO 2 is ∼3 m 0 (the free electron mass). 41 P25 also contains the rutile phase, which has a high of ∼50 m 0 . 47 Thus, it is reasonable to assume that the N CB is 10 21 cm 3 .…”

“…Photoconductance was measured in a self-designed device under a methanol-containing N 2 flow according to our previous work. 41,42 A 0.05 mm-wide FTO strip of a 20 mm  20 mm FTO glass was firstly removed by laser etching, and the pure TiO 2 and Ag/TiO 2 samples were coated on the FTO-removed area, and then dried at 50 1C to form a sample coating for conductance measurements. Conductance was measured using Keithley-2450 SourceMeter with a 2 V bias voltage in two-probe mode at different temperatures.…”

Catalytic Metasurfaces Empowered by Bound States in the Continuum

“…Hence, obtaining strong light absorption in ultrathin semiconductors has been of great scientific and technological interest for many years, making it one of the essential aspects for the efficient generation of photocarriers, as well as the development of ultrafast optoelectronic devices − and surface-active photocatalysts. , However, ultrathin films of many naturally occurring semiconductor materials provide only limited freedom for controlling the spectral location and magnitude of light absorption, since their intrinsic optical properties are fixed . In contrast, ultrathin metasurfaces constructed from two-dimensional subwavelength arrays of semiconductor structures have shown tremendous potential for concentrating and controlling light on the nanoscale, positioning them as an ideal toolkit for engineering the light absorption in catalytic materials. − Indeed, recent examples have shown that such artificial materials can increase the internal quantum efficiency of semiconductors and metals when shaping them into catalytic metasurfaces. , …”

Kinetic pathways of sub-bandgap induced electron transfer in Ag/TiO2 and the effect on isopropanol dehydrogenation under gaseous conditions

“…We have revealed that the sub-bandgap light responses of undecorated TiO 2 presented a great decrease as sub-bandgap light wavelengths increased from 450 nm to 532 nm. 17 According to Fig. 2(a), as the plasmon extinctions at 450 nm and 532 nm do not differ much from each other, it is thus expected that the electrons transferring from Ag nanoparticles to TiO 2 cannot differ greatly for the two wavelength laser illuminations, but should be basically proportional to their plasmon absorbances.…”

“…3, the valence electrons were firstly promoted to the gap states with sub-bandgap photons, which can then be thermally activated to the CB states. 17 In addition, the plasmon-induced hot electrons in the Ag nanoparticles can also transfer to TiO 2 due to the low interfacial Schottky barrier; 21,22 this is known as the plasmon-induced charge separation (PICS) and has been considered a physical cause for the plasmon-assisted photocatalytic reactions over metal/semiconductor systems. For example, it has been seen that the photoelectrochemical currents can accord with the Ag plasmon extinction spectrum under aqueous conditions; this indicates that the plasmonic electron injection caused the photocatalytic effect.…”