Interfacial Charge-Transfer Transitions between TiO₂ Nanoparticles and Benzoic Acid Derivatives

Abstract

Interfacial charge-transfer transitions (ICTTs) between organic compounds and inorganic semiconductors have recently attracted increasing interest for their potential applications in photoenergy conversions and chemical sensing because of the unique features of visible-light absorption with colorless organic molecules and direct photoinduced charge separation. The exploration of new organic−inorganic hybrid materials for ICTT is an important subject for expanding the scope and utility of ICTT widely. TiO 2 nanoparticles chemically linked to aromatic carboxylic acids are one of the most important photoinduced electron-transfer systems in the above applications. Here, we systematically examine the electronic and optical properties of surface coordination complexes of TiO 2 nanoparticles with benzoic acid (BA) and its derivatives experimentally and computationally. Our research unambiguously reveals that ICTT generally takes place between TiO 2 nanoparticles and BA derivatives possessing electrondonating groups, and the absorption wavelength range can be controlled by adjusting the electron-donating ability and the number of substituent groups. Our research widely expands the scope and utility of ICTT and provides a new guiding principle for material development of interfacial light absorbers featuring direct photoinduced charge separation for photoenergy conversions.

Interfacial Charge-Transfer Transitions in Weakly Coupled TiO2 Complexes with Aromatic Monothiols for Visible-Light Photocatalytic Reactions

“…Then, the TiO 2 nanoparticles were filtered and washed lightly with acetonitrile and then vacuum-dried. Because it was reported that the disulfide formation proceeds very slowly even under dark conditions, we shortened the immersion time to 30 min, which is much shorter than the conventional time (24 h) for preparing the above-mentioned strongly coupled complexes. ,,− The TiO 2 blank sample was prepared by immersing anatase TiO 2 nanoparticles (0.1 g) in acetonitrile (10 mL) under dark conditions, filtering, and vacuum-drying them. These samples are denoted by TiO 2 -BT, TiO 2 -4-MOBT, TiO 2 -4-DMABT, and TiO 2 .…”

“…Particularly, surface coordination complexes of wide band-gap inorganic semiconductors such as TiO 2 with organic compounds possessing anchoring groups characteristically show interfacial charge-transfer transitions (ICTTs), which enable the absorption of visible light for colorless organic molecules and direct photoinduced charge separation at the organic–inorganic interfaces, as shown in Figure . − Because of these features, ICTTs have attracted increasing interest as a new visible-light absorption mechanism and a direct photoinduced charge-separation mechanism for photoenergy conversions such as photovoltaic conversion ,− and photocatalytic reactions − and for chemical/biological sensing based on direct visualization, ,,− surface enhanced Raman scattering, − and visible-light circular dichroism of colorless organic compounds. So far, ICTTs have been studied intensively in strongly coupled complexes of inorganic semiconductors (TiO 2 , − SrTiO 3 , BaTiO 3 , , ZnO, − SnO 2 , etc.) with aromatic or π-conjugated organic molecules that possess anchoring groups (−OH, − ,,…”

“…So far, ICTTs have been studied intensively in strongly coupled complexes of inorganic semiconductors (TiO 2 , − SrTiO 3 , BaTiO 3 , , ZnO, − SnO 2 , etc.) with aromatic or π-conjugated organic molecules that possess anchoring groups (−OH, − ,, −SH, ,,, −COOH, − ,, −NH–, ,,, etc.). Accordingly, the basic and applied research of ICTTs has focused on the strongly coupled complexes, which can be isolated without remarkable desorption of the adsorbed molecules.…”

A Wearable PVA Film Supported TiO2 Nanoparticles Decorated NaNbO3 Nanoflakes‐Based SERS Sensor for Simultaneous Detection of Metabolites and Biomolecules in Human Sweat Samples

“…Titanium dioxide (TiO 2 ) is a widely reported semiconductor TMO platform for SERS application for the detection of various biomolecules via charge transfer mechanism or chemical mechanism. [ 21 ] Huang et al. reported sliver (Ag)‐TiO 2 nanocomposites as a SERS substrate for detection of uracil DNA glycolase in Hela cell lysate.…”

“…The surface coordination between the substrate and the analytes plays a major role in the enhanced Raman scattering via the phenomenon of interfacial charge transfer transition (ICTT). [ 21 ] The ICTT can be attributed to the electronic coupling between the TiO 2 @NaNbO 3 and analyte via coordinate covalent bonding between them. To the best of our knowledge, this is the first report on TiO 2 nanoparticles decorated NaNbO 3 nanoflakes with the flexible PVA dermal patch for the SERS detection of metabolites (such as glucose and urea) and biomolecules (such as ascorbic acid and uric acid) in the human sweat samples.…”