Charge Separation at Pd−Porphyrin/TiO₂ Interfaces

Abstract

Charge separation has been investigated at Pd−porphyrin (Pd−P)/TiO2 interfaces by surface photovoltage spectroscopy in the Kelvin-probe arrangement. Ultrathin nanoporous TiO2 layers were covered with Pd−P molecules from highly diluted organic solution starting from the submonolayer range. Mechanisms of charge separation including charge separation in TiO2 nanoparticles, an ionic transport component, and injection of electrons into TiO2 from states of solitary Pd−P molecules not interacting with each other on the surface and from Pd−P molecules interacting with each other and with TiO2 were identified. A developed model for the simulation of surface photovoltage spectra considered mechanisms of charge separation and respective recombination paths. Characteristic charge separation lengths and recombination coefficients were obtained for the different components of separated charge.

3D Branched Ca‐Fe2O3/Fe2O3 Decorated with Pt and Co‐Pi: Improved Charge‐Separation Dynamics and Photoelectrochemical Performance

“…The other is that the homogeneous combination of n-type Fe 2 O 3 and p-type Ca-Fe 2 O 3 leads to as trongb uilt-in electric field, which brings about the cathodic shift in onset potential. [32] Finally,t he charge-recombination behavior was evaluated by photoluminescence (PL) spectral analysis (Figure S5, Supporting Information). Notably, the magnified inset image clearly displays positive and negative spikes under choppedi llumination.…”

Photochemical charge transfer observed in nanoscale hydrogen evolving photocatalysts using surface photovoltage spectroscopy

“…The higher sensitivity allows the observation of localized charge transfer states with small optical cross sections. 17,[21][22][23][24][25][26][27][28] As a model system we use single crystalline nanoparticles of Rh-doped SrTiO 3 . SrTiO 3 is an established photocatalyst for overall water splitting under UV light only, 18,21,[29][30][31] but it can be converted into a visible light responsive material upon doping with Cr, 32 Cr/Sb, 33,34 Cr/Ta, 35 Rh, 36,37 Ni/Ta, 38 and…”

Charge Separation in Donor–Acceptor Spiro Compounds at Metal and Metal Oxide Surfaces Investigated by Surface Photovoltage

“…Regarding to previous experience molecular layers with a thickness of the order of one monolayer can be deposited from highly diluted solutions. 12 After deposition the samples were transferred within several seconds into a vacuum chamber (pressure 10 −5 mbar) for SPV measurements in the Kelvin-probe (dc-SPV, delta phi Besocke) or fixed capacitor (ac-SPV, modulated) configurations. A quartz cylinder coated with FTO and a mica sheet served as the electrode and spacer, respectively, for SPV measurements in the fixed capacitor arrangement.…”