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Title: PHOTOELECTROCHEMISTRY AND PHOTOCATALYSIS IN NANOSCALE INORGANIC CHEMICAL SYSTEMS

Abstract

The goal of our DOE-supported research has been to explore the use of solid state materials as organizing media for, and as active components of, artificial photosynthetic systems. In this work we strive to understand how photoinduced electron and energy transfer reactions occur in the solid state, and to elucidate design principles for using nanoscale inorganic materials in photochemical energy conversion schemes. A unifying theme in this project has been to move beyond the study of simple transient charge separation to integrated chemical systems that can effect permanent charge separation in the form of energy-rich chemicals. This project explored the use of zeolites as organizing media for electron donor-acceptor systems and artificial photosynthetic assemblies. Layer-by-layer synthetic methods were developed using lamellar semiconductors, and multi-step, visible light driven energy/electron transfer cascades were studied by transient specroscopic techniques. By combining molecular photosensitizers with lamellar semiconductors and intercalated catalyst particles, the first non-sacrificial systems for visible light driven hydrogen evolution were developed and studied. Oxygen evolving catalyst particles and semiconductor nanowires were also studied with the goal of achieving photocatalytic water splitting using visible light.

Authors:
Publication Date:
Research Org.:
The Pennsylvania State University
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
907952
Report Number(s):
DOE/ER/14374-12
TRN: US200722%%383
DOE Contract Number:
FG02-93ER14374
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; DESIGN; ELECTRONS; ENERGY CONVERSION; ENERGY TRANSFER; HYDROGEN; OXYGEN; PHOTOCATALYSIS; WATER; ZEOLITES; ELECTROCHEMISTRY; Solar photochemistry, electron transfer, energy transfer, self-assembly, photosensitization, catalysis, photocatalysis, semiconductors

Citation Formats

Thomas E. Mallouk. PHOTOELECTROCHEMISTRY AND PHOTOCATALYSIS IN NANOSCALE INORGANIC CHEMICAL SYSTEMS. United States: N. p., 2007. Web. doi:10.2172/907952.
Thomas E. Mallouk. PHOTOELECTROCHEMISTRY AND PHOTOCATALYSIS IN NANOSCALE INORGANIC CHEMICAL SYSTEMS. United States. doi:10.2172/907952.
Thomas E. Mallouk. Sun . "PHOTOELECTROCHEMISTRY AND PHOTOCATALYSIS IN NANOSCALE INORGANIC CHEMICAL SYSTEMS". United States. doi:10.2172/907952. https://www.osti.gov/servlets/purl/907952.
@article{osti_907952,
title = {PHOTOELECTROCHEMISTRY AND PHOTOCATALYSIS IN NANOSCALE INORGANIC CHEMICAL SYSTEMS},
author = {Thomas E. Mallouk},
abstractNote = {The goal of our DOE-supported research has been to explore the use of solid state materials as organizing media for, and as active components of, artificial photosynthetic systems. In this work we strive to understand how photoinduced electron and energy transfer reactions occur in the solid state, and to elucidate design principles for using nanoscale inorganic materials in photochemical energy conversion schemes. A unifying theme in this project has been to move beyond the study of simple transient charge separation to integrated chemical systems that can effect permanent charge separation in the form of energy-rich chemicals. This project explored the use of zeolites as organizing media for electron donor-acceptor systems and artificial photosynthetic assemblies. Layer-by-layer synthetic methods were developed using lamellar semiconductors, and multi-step, visible light driven energy/electron transfer cascades were studied by transient specroscopic techniques. By combining molecular photosensitizers with lamellar semiconductors and intercalated catalyst particles, the first non-sacrificial systems for visible light driven hydrogen evolution were developed and studied. Oxygen evolving catalyst particles and semiconductor nanowires were also studied with the goal of achieving photocatalytic water splitting using visible light.},
doi = {10.2172/907952},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun May 27 00:00:00 EDT 2007},
month = {Sun May 27 00:00:00 EDT 2007}
}

Technical Report:

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  • Subsurface solute transport in solid-aqueous systems of nonconservative chemical species is often controlled by adsorption and desorption reactions. Three projects are briefly discussed which utilize alternate experimental techniques: (1) adsorbate induced particle-particle aggregation analyzed by electrophoretic mobility distribution; (2) heats of anion adsorption using microcalorimetry; and (3) in situ studies of salicylic acid adsorption on goethite using CIR-FTIR Spectroscopy. 7 refs., 2 figs. (ACR)
  • Our primary goal in this research is to investigate the reaction mechanisms and important non-biological variables which affect the partitioning of microcontaminants in aqueous systems between the bulk solution and solid-phase adsorbents. The primary technique used for this work is cylindrical internal reflection-Fourier transform infrared (CIR-FTIR) spectroscopy, in conjunction with wet chemical adsorption studies, and electrophoretic mobility and acoustophoresis measurements. We have had limited success in attempting to develop CIR-FTIR spectroscopy into a quantitative technique for the study of suspensions. Difficulties are related primarily to the nature of the arrangement of suspension particles around the CIR crystal and the designmore » of the CIR optics. Because of the importance of particle-particle interactions and agglomeration in these more concentrated suspensions, we are using a new technique, acoustophoresis, to aid in evaluating the interparticle forces which determine the arrangement of these particles. These interparticle forces affect particle-particle organization not only in the CIR cell but also in the environment. This report discusses our initial efforts to utilize acoustophoresis instrumentation. 7 refs., 4 figs.« less
  • Goal is to investigate the reaction mechanisms and key nonbiological variables which affect the partitioning of microcontaminants between aqueous solutions and solid phase adsorbents. The primary technique used is cylindrical internal reflection - Fourier transform infrared (CIR-FTIR) spectroscopy, in conjunction with wet chemical adsorption isotherm and electrophoretic mobility measurements. CIR-FTIR study of the adsorption of phenol, benzoic acid and derivatives on goethite indicated that phenol and o-nitrophenol do not adsorb. Two separate adsorption mechanisms were observed for five other organics: (1) bidentate adsorption; (2) chelate adsorption along crystal edges. Phosphate adsorption was also studied using CIR-FTIR, with a bidentate adsorptionmore » mechanism also indicated. Another aspect of this investigation is to determine the effect of possible particle aggregation on adsorption. This aspect requires the use of a Matec Instruments System 8010, which is currently being purchased. 4 refs.« less
  • In order to predict, in time and space, movement or attenuation of organic and inorganic solutes in heterogeneous subsurface environments, it is necessary to describe the dynamic interplay or competition that exists between aqueous solutions and solid surfaces for given solutes. Often, this competition ultimately determines the degrees of solute mobility. For transport modeling, competition is expressed simply as retardation factors. This report essentially reviews results from the independent studies which have all been designed as research probes into the nature of interfacial reactions: (1) phenol adsorption onto goethite; (2) electrostatic contributions in protolyzable anion adsorption; and (3) the effectmore » of chemical and physical coagulation on the uptake of phosphorus by goethite. These studies represent state of the art contributions to the total level of effort being made by the research community in a rapidly expanding attempt to understand the adsorption of trace contaminants in heterogeneous systems.« less
  • In order to model transport of dissolved ions in subsurface environments, one should understand how these ions interact with solid phase adsorbents. Our primary goal has been investigating the reaction mechanisms which affect microcontaminant partitioning between aqueous solutions and solid phase adsorbents, using goethite ({alpha}-FeOOH) as a model adsorbent. Cylindrical internal reflection -- Fourier transform infrared (CIR-FTIR) spectroscopy has been developed as the primary technique for this study. Wet chemical adsorption studies, acoustophoresis and electrophoretic mobility have been used to obtain supporting information as needed. Phenol and o-nitrophenol did not adsorb to goethite. Benzoate, phthalate and p-hydroxybenzoate all adsorbed viamore » a bidentate mechanism to two adjacent iron atoms, while salicylate and 2,4-dihydroxybenzoate formed a chelate complex to single iron atoms. Phosphate adsorption was predominately bidentate.« less