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Khachatryan L, Rezk MY, Nde D, Hasan F, Lomnicki S, Boldor D, Cook R, Sprunger P, Hall R, Cormier S. New Features of Laboratory-Generated EPFRs from 1,2-Dichlorobenzene (DCB) and 2-Monochlorophenol (MCP). ACS OMEGA 2024; 9:9226-9235. [PMID: 38434874 PMCID: PMC10905596 DOI: 10.1021/acsomega.3c08271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 12/18/2023] [Accepted: 01/22/2024] [Indexed: 03/05/2024]
Abstract
The present research is primarily focused on investigating the characteristics of environmentally persistent free radicals (EPFRs) generated from commonly recognized aromatic precursors, namely, 1,2-dichlorobenzene (DCB) and 2-monochlorophenol (MCP), within controlled laboratory conditions at a temperature of 230 °C, termed as DCB230 and MCP230 EPFRs, respectively. An intriguing observation has emerged during the creation of EPFRs from MCP and DCB utilizing a catalyst 5% CuO/SiO2, which was prepared through various methods. A previously proposed mechanism, advanced by Dellinger and colleagues (a conventional model), postulated a positive correlation between the degree of hydroxylation on the catalyst's surface (higher hydroxylated, HH and less hydroxylated, LH) and the anticipated EPFR yields. In the present study, this correlation was specifically confirmed for the DCB precursor. Particularly, it was observed that increasing the degree of hydroxylation at the catalyst's surface resulted in a greater yield of EPFRs for DCB230. The unexpected finding was the indifferent behavior of MCP230 EPFRs to the surface morphology of the catalyst, i.e., no matter whether copper oxide nanoparticles are distributed densely, sparsely, or completely agglomerated. The yields of MCP230 EPFRs remained consistent regardless of the catalyst type or preparation protocol. Although current experimental results confirm the early model for the generation of DCB EPFRs (i.e., the higher the hydroxylation is, the higher the yield of EPFRs), it is of utmost importance to closely explore the heterogeneous alternative mechanism(s) responsible for generating MCP230 EPFRs, which may run parallel to the conventional model. In this study, detailed spectral analysis was conducted using the EPR technique to examine the nature of DCB230 EPFRs and the aging phenomenon of DCB230 EPFRs while they exist as surface-bound o-semiquinone radicals (o-SQ) on copper sites. Various aspects concerning bound radicals were explored, including the hydrogen-bonding tendencies of o-semiquinone (o-SQ) radicals, the potential reversibility of hydroxylation processes occurring on the catalyst's surface, and the analysis of selected EPR spectra using EasySpin MATLAB. Furthermore, alternative routes for EPFR generation were thoroughly discussed and compared with the conventional model.
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Affiliation(s)
- Lavrent Khachatryan
- Department
of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Marwan Y. Rezk
- Department
of Engineering Science, Biological Engineering, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Divine Nde
- Department
of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Farhana Hasan
- Department
of Environmental Sciences, Louisiana State
University, Baton
Rouge, Louisiana 70803, United States
| | - Slawomir Lomnicki
- Department
of Environmental Sciences, Louisiana State
University, Baton
Rouge, Louisiana 70803, United States
| | - Dorin Boldor
- Department
of Engineering Science, Biological Engineering, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Robert Cook
- Department
of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Phillip Sprunger
- Department
of Physics and Astronomy, Louisiana State
University, Baton
Rouge, Louisiana 70803, United States
| | - Randall Hall
- Natural
Sciences and Mathematics, School of Health and Natural Sciences, Dominican University of California, San Rafael, California 94901, United States
| | - Stephania Cormier
- Department
of Biological Sciences, LSU Superfund Research
Program and Pennington Biomedical Research Center, Baton Rouge, Louisiana 70808, United States
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Punia B, Chaudhury S, Kolomeisky A. How Heterogeneity Affects Cooperative Communications within Single Nanocatalysts. J Phys Chem Lett 2023; 14:8227-8234. [PMID: 37672790 DOI: 10.1021/acs.jpclett.3c01874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/08/2023]
Abstract
Catalysis remains one of the most essential methods in chemical research and industry. Recent experiments have discovered an unusual phenomenon of catalytic cooperativity, when a reaction at one active site can stimulate reactions at neighboring sites within single nanoparticles. While theoretical analysis established that the transport of charged holes is responsible for this phenomenon, it does not account for inhomogeneity in the structural and dynamic properties of single nanocatalysts. Here, we investigate the effect of heterogeneity on catalytic communications by extending a discrete-state stochastic framework to random distributions of the transition rates. Our explicit calculations of spatial and temporal properties of heterogeneous systems in comparison with homogeneous systems predict that the strength of cooperativity increases, while the communication lifetimes and distances decrease. Monte Carlo computer simulations support theoretical calculations, and microscopic arguments to explain these observations are also presented. Our theoretical analysis clarifies some important aspects of molecular mechanisms of catalytic processes.
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Affiliation(s)
- Bhawakshi Punia
- Department of Chemistry, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune 411008, Maharashtra, India
| | - Srabanti Chaudhury
- Department of Chemistry, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune 411008, Maharashtra, India
| | - Anatoly Kolomeisky
- Department of Chemistry, Department of Chemical and Biomolecular Engineering, Department of Physics and Astronomy, and Center for Theoretical Biological Physics, Rice University, 6100 Main Street, Houston, Texas 77005, United States
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Chaudhury S, Jangid P, Kolomeisky AB. Dynamics of chemical reactions on single nanocatalysts with heterogeneous active sites. J Chem Phys 2023; 158:074101. [PMID: 36813720 DOI: 10.1063/5.0137751] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Modern chemical science and industries critically depend on the application of various catalytic methods. However, the underlying molecular mechanisms of these processes still remain not fully understood. Recent experimental advances that produced highly-efficient nanoparticle catalysts allowed researchers to obtain more quantitative descriptions, opening the way to clarify the microscopic picture of catalysis. Stimulated by these developments, we present a minimal theoretical model that investigates the effect of heterogeneity in catalytic processes at the single-particle level. Using a discrete-state stochastic framework that accounts for the most relevant chemical transitions, we explicitly evaluated the dynamics of chemical reactions on single heterogeneous nanocatalysts with different types of active sites. It is found that the degree of stochastic noise in nanoparticle catalytic systems depends on several factors that include the heterogeneity of catalytic efficiencies of active sites and distinctions between chemical mechanisms on different active sites. The proposed theoretical approach provides a single-molecule view of heterogeneous catalysis and also suggests possible quantitative routes to clarify some important molecular details of nanocatalysts.
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Affiliation(s)
- Srabanti Chaudhury
- Department of Chemistry, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune, Maharashtra 411008, India
| | - Pankaj Jangid
- Department of Chemistry, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune, Maharashtra 411008, India
| | - Anatoly B Kolomeisky
- Department of Chemistry, Department of Physics and Astronomy, Department of Chemical and Biomolecular Engineering and Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005-1892, USA
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