Adsorption, Desorption, and Sensitization of Low-Index Anatase and Rutile Surfaces by the Ruthenium Complex Dye N3

Abstract

Single-crystal anatase(101), (001) and rutile(100), (001) surfaces with atomically flat terraces were prepared and their structure verified with atomic force microscopy. A ruthenium complex dye, cis-di(thiocyanato)-bis( 2,2′ -bipyridyl- 4,4′ -dicarboxylate) ruthenium(II) (usually known as N3) was used to sensitize these surfaces. The N3 coverage dependence of the incident photon to current efficiencies (IPCE) was measured for all four surfaces. IPCE values were much higher on anatase(101) and rutile(100) than on the other two surfaces. The kinetics of N3 adsorption was also studied on the four surfaces. The adsorption kinetics for a slow adsorption step could be fit with a Langmuir kinetic model. The differences in the adsorption of N3 and the IPCE values are discussed based on the structure of the N3 and the geometry and reactivity of the binding sites on the four surfaces.

Differences in adsorption behavior of N3 dye on flat and nanoporous TiO2 surfaces

“…Recently, Parkinson and coworkers evaluated the density of adsorbed N3 dye on TiO 2 single crystals by means of photochronocoulometric measurements [13]. They obtained a density of 0.60 molecules nm À2 (S full = 1.6 nm 2 ) for N3 dye adsorbed on the rutile (1 0 0) TiO 2 surface from 0.22 mM ethanol solution, which is slightly lower than the results shown in Fig.…”

A surface science perspective on TiO2 photocatalysis

“…While much discussion in the literature has focused on optimizing the properties of the dye and the redox couples, attention here will be on the properties of TiO 2 as an electron acceptor. Coupling between the excited dye's electronic structure and the TiO 2 CB states is so strong that injection yields approaching 100% have been measured for many different dyes [610,612,622,623,631,633,636,638,640,652]. Another reflection of the strong coupling is that electron injection typically occurs on the sub-picosecond timescale [390,494,601,613,624,628,629,637,638,640,641,643,647,667,669], and in some cases faster than 100 fs [163,198,391,532,536,606,607,609,617,618,625,632,[649][650][651]655,656,662,666].…”

“…However, several groups have examined electron transfer between an excited dye and a single crystal TiO 2 surface [116,390,391,626,633,655,[671][672][673][674]. Schnadt et al [655] were one of the first groups to use the R TiO 2 (110) surface to study the dynamics of electron injection, albeit in their case from resonant core-hole excitation of adsorbed isonicotinic and biisonicotinic acids rather than via visible light absorption.…”

A Double‐Band Tandem Organic Dye‐sensitized Solar Cell with an Efficiency of 11.5 %

“…According to the Mott-Schottky equation, a linear relationship between C À2 vs. E is observed. [19][20] The ZrO 2 -doped sample has a different slope and intercept compared to the pure TiO 2 sample. The flat-band potentials of the bare TiO 2 and ZrO 2 -doped TiO 2 were determined to be À0.54 V and À0.62 V (vs. Ag/AgCl), respectively; clearly, the open-circuit potential of the ZrO 2 -doped electrode is negatively shifted by 80 mV compared to the undoped TiO 2 electrode.…”