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Kinetics of Stochastic Charge Transfer and Recombination Events in Semiconductor Colloids. Relevance to Photocatalysis Efficiency

Grela, María A. and Colussi, Agustín J. (1996) Kinetics of Stochastic Charge Transfer and Recombination Events in Semiconductor Colloids. Relevance to Photocatalysis Efficiency. Journal of Physical Chemistry, 100 (46). pp. 18214-18221. ISSN 0022-3654 . http://resolver.caltech.edu/CaltechAUTHORS:20150623-154803076

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Abstract

We report stochastic calculations in compact 2-D lattices modeling the competition between electron−hole recombination and reactive processes on the surface of illuminated TiO_2 colloidal particles. Computer simulations in which holes perform unbiased random walks, react with oxidizable donors, or neutralize stationary electrons, while the latter reduce O_2 confirm that conventional kinetic concepts and rate laws are invalid in such domains. Bimolecular carrier recombination never follows second-order kinetics:  single excitons decay exponentially and multiple pairs annihilate with second-order rate coefficients asymptotically approaching a t^(-1/2) dependence. The occurrence of discrete events at the microscopic level further implies that (1) anodic and cathodic processes do not necessarily occur synchronously and (2) the fastest, rather than the slowest, charge transfer reaction is yield-determining. We carry out a rigorous data reduction analysis of experimental recombination rates and explore photon flux, [O_2], and particle size effects on the quantum yield of photocatalytic oxidations in these systems. Under typical steady-state illumination conditions, the model predicts that primary photooxidation yields should be nearly independent of photon flux and [O_2] over wide ranges and increase with particle radius.


Item Type:Article
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URLURL TypeDescription
http://dx.doi.org/10.1021/jp961936qDOIArticle
http://pubs.acs.org/doi/abs/10.1021/jp961936qPublisherArticle
ORCID:
AuthorORCID
Colussi, Agustín J.0000-0002-3400-4101
Additional Information:© 1996 American Chemical Society. Received: July 1, 1996; In Final Form: September 10, 1996. This project was financially supported by the National Research Council of Argentina (CONICET) under Grant PID 1131/91.
Funders:
Funding AgencyGrant Number
Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)PID 1131/91
Record Number:CaltechAUTHORS:20150623-154803076
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20150623-154803076
Official Citation:Kinetics of Stochastic Charge Transfer and Recombination Events in Semiconductor Colloids. Relevance to Photocatalysis Efficiency María A. Grela and Agustín J. Colussi The Journal of Physical Chemistry 1996 100 (46), 18214-18221 DOI: 10.1021/jp961936q
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:58503
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:24 Jul 2015 20:19
Last Modified:24 Jul 2015 20:19

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