Photo-Induced Electron Migrations in the Nano-Cavities of Mesoporous Silica Sensitized by a Cationic Porphyrin Dye

Abstract

Photo-induced redox reactions in a hybrid film of a cationic porphyrin dye (H2TMPyP) accommodated within a transparent mesoporous silica (MPS) film spin-coated on an FTO electrode have been investigated for such applications as the construction of efficient solar energy storage devices and novel light-stimulated sensors. In this system, anodic and cathodic photocurrents were observed under bias voltages of +0.3 V and -0.4 V, respectively. The action spectrum of the photocurrents corresponded well with the absorbance of the H2TMPyP molecules in the visible light region. Control experiments showed no photocurrents for the mesoporous silica without H2TMPyP. Our investigations showed that the H2TMPyP molecules function not only as a sensitizer but also as a mediator for electron migrations within mesoporous nano-cavities.

Potential Driven Non-Reactive Phase Transitions of Ordered Porphyrin Molecules on Iodine-Modified Au(100): An Electrochemical Scanning Tunneling Microscopy (EC-STM) Study

“…Among other examples, porphyrins, due to the wide range of potential applications of this class of molecules, e.g., in cancer therapy [16,17], catalysis [18,19], and sensing [20,21], have become prototypical systems for the fabrication and design of supramolecular nanoarchitectures and the characterization of their formation mechanism [22,23]. As an example from the point of applications, tetra (N-methyl-4-pyridyl)-porphyrin p-tolylsulfonate molecules (H 2 TMPyP, Figure 1) were proven to be good sensors for the detection of benzene and heavy metal ions (Hg 2+ , Pb 2+ , Cd 2+ ) in water [24].…”

Mesoporous silica nanoparticles: structural design and applications

“…20,21 Other important applications included the development of sensors and energy transfer devices. [22][23][24][25][26][27] Though exciting, all of these early applications were still limited by a lack of control of particle size and morphology. The ability to produce particulate material with defined shapes and monodispersed sizes would increase further the spectrum of applications of mesoporous silicas.…”

Unveiling the Interplay between a Au(100) Electrode, Adsorbed TTMAPP Porphyrin Cations, and Iodide Anions: An EC-STM and CV Study

“…For example, 5,10,15,20-tetrakis-(N-methyl-4-pyridyl) porphyrin (TMPyP) and 5,10,15,20tetrakis(4-trimethylammoniophenyl) porphyrin (TTMAPP)tetra(p-toluenesulfonate) (Figure 1) have been investigated for diverse applications, including cancer therapy, 18,21 catalysis, 22,23 and sensing. 24,25 TMPyP, for instance, has demonstrated sensing capabilities for benzene 26 ions 27 in water, while TTMAPP was found to be a promising photodynamic inactivator of bacterial membrane. 28 Moreover, a silica-TTMAPP complex is a constituent of nanocomposite liposomes that are used for treating human prostate cancer cells.…”