Catalytic resonance theory

{{Short description|Theory in chemistry}}

{{Short description|Theory in chemistry}}

In [[chemistry]], '''catalytic resonance theory''' was developed to describe the kinetics of reaction acceleration using dynamic [[catalyst]] surfaces. Catalytic reactions occur on surfaces that undergo variation in surface binding [[energy]] and/or [[entropy]], exhibiting overall increase in reaction rate when the surface binding energy [[frequencies]] are comparable to the natural frequencies of the surface reaction, [[adsorption]], and [[desorption]].

In [[chemistry]], '''catalytic resonance theory''' was developed to describe the kinetics of reaction acceleration using dynamic [[catalyst]] surfaces. Catalytic reactions occur on surfaces that undergo variation in surface binding [[energy]] and/or [[entropy]], exhibiting overall increase in [[reaction rate]] when the surface binding energy [[frequencies]] are comparable to the natural frequencies of the surface reaction, [[adsorption]], and [[desorption]].

==History==

==History==

[[File:SelectivityResonance.jpg|thumb|left|The catalytic reactions of A-to-B and A-to-C can be controlled by applying dynamic binding energy to the surface with varying applied frequency and fixed amplitude starting at varying energies.]]

[[File:SelectivityResonance.jpg|thumb|left|The catalytic reactions of A-to-B and A-to-C can be controlled by applying dynamic binding energy to the surface with varying applied frequency and fixed amplitude starting at varying energies.]]

Surface binding energy [[oscillation]] also occurs to different extent with the various chemical surface species as defined by the γ_i-j parameter. For any non-unity γ_i-j system, the asymmetry in the surface energy profile results in conducting work to bias the reaction to a steady state away from equilibrium.{{cite journal |doi=10.1021/acscatal.9b01606 |author=M.A. Ardagh |author2=Turan Birol |author3=Q. Zhang |author4=O.A. Abdelrahman |author5=P.J. Dauenhauer |title=Catalytic Resonance Theory: superVolcanoes, catalytic molecular pumps, and oscillatory steady state |journal=Catalysis Science & Technology |year=2019|s2cid=182444068 |url=https://figshare.com/articles/Principles_of_Dynamic_Heterogeneous_Catalysis_Surface_Resonance_and_Turnover_Frequency_Response/7790009 }} Similar to the controlled directionality of [[molecular machines]], the resulting [[ratchet (device)]] energy mechanism selectively moves molecules through a catalytic reaction against a free energy gradient.{{cite book |last=Hoffmann |first=Peter |date=October 30, 2012 |title=Life's Ratchet: How Molecular Machines Extract Order from Chaos |url=https://books.google.com/books?id=zFUIvHbnP2wC |publisher=Basic Books |isbn=978-0465022533 }}

Surface binding energy [[oscillation]] also occurs to different extent with the various chemical surface species as defined by the γ_i-j parameter. For any non-unity γ_i-j system, the asymmetry in the [[surface energy]] profile results in conducting work to bias the reaction to a steady state away from equilibrium.{{cite journal |doi=10.1021/acscatal.9b01606 |author=M.A. Ardagh |author2=Turan Birol |author3=Q. Zhang |author4=O.A. Abdelrahman |author5=P.J. Dauenhauer |title=Catalytic Resonance Theory: superVolcanoes, catalytic molecular pumps, and oscillatory steady state |journal=Catalysis Science & Technology |year=2019|s2cid=182444068 |url=https://figshare.com/articles/Principles_of_Dynamic_Heterogeneous_Catalysis_Surface_Resonance_and_Turnover_Frequency_Response/7790009 }} Similar to the controlled directionality of [[molecular machines]], the resulting [[ratchet (device)]] energy mechanism selectively moves molecules through a catalytic reaction against a free energy gradient.{{cite book |last=Hoffmann |first=Peter |date=October 30, 2012 |title=Life's Ratchet: How Molecular Machines Extract Order from Chaos |url=https://books.google.com/books?id=zFUIvHbnP2wC |publisher=Basic Books |isbn=978-0465022533 }}

Application of dynamic binding energy to a surface with multiple catalytic reactions exhibits complex behavior derived from the differences in the natural frequencies of each chemistry; these frequencies are identified by the inverse of the adsorption, desorption, and surface kinetic rate parameters. Considering a system of two parallel elementary reactions of A-to-B and A-to-C that only occur on a surface, the performance of the [[catalyst]] under dynamic conditions will result in varying capability for selecting either reaction product (B or C).{{cite journal |doi=10.1039/C9SC06140A|pmc=8152411 |author=M.A. Ardagh |author2=M. Shetty |author3=A. Kuznetsov|author4=Q. Zhang |author5=P. Christopher |author6=D.G. Vlachos |author7=O.A. Abdelrahman |author8=P.J. Dauenhauer |title=Catalytic Resonance Theory: Parallel Reaction Pathway Control |journal=Chemical Science |year=2020|volume=11 |issue=13 |pages=3501–3510 |pmid=34109022 |doi-access=free }} For the depicted system, both reactions have the same overall [[thermodynamics]] and will produce B and C in equal amounts (50% selectivity) at [[chemical equilibrium]]. Under normal static catalyst operation, only product B can be produced at selectivities greater than 50% and product C is never favored. However, as shown, the application of surface binding dynamics in the form of a square wave at varying [[frequency]] and fixed oscillation [[amplitude]] but varying endpoints exhibits the full range of possible reactant selectivity. In the range of 1-10 [[Hertz]], there exists a small island of parameters for which product C is highly selective; this condition is only accessible via dynamics.{{cite journal |doi=10.26434/chemrxiv.10271090.v1 |author=M.A. Ardagh |author2=M. Shetty |author3=A. Kuznetsov|author4=Q. Zhang |author5=P. Christopher |author6=D.G. Vlachos |author7=O.A. Abdelrahman |author8=P.J. Dauenhauer |title=Catalytic Resonance Theory: Parallel Reaction Pathway Control |journal=ChemRxiv |year=2019|url=https://chemrxiv.org/ndownloader/files/18549938 |doi-access=free }}

Application of dynamic binding energy to a surface with multiple catalytic reactions exhibits complex behavior derived from the differences in the natural frequencies of each chemistry; these frequencies are identified by the inverse of the adsorption, desorption, and surface kinetic rate parameters. Considering a system of two parallel elementary reactions of A-to-B and A-to-C that only occur on a surface, the performance of the [[catalyst]] under dynamic conditions will result in varying capability for selecting either reaction product (B or C).{{cite journal |doi=10.1039/C9SC06140A|pmc=8152411 |author=M.A. Ardagh |author2=M. Shetty |author3=A. Kuznetsov|author4=Q. Zhang |author5=P. Christopher |author6=D.G. Vlachos |author7=O.A. Abdelrahman |author8=P.J. Dauenhauer |title=Catalytic Resonance Theory: Parallel Reaction Pathway Control |journal=Chemical Science |year=2020|volume=11 |issue=13 |pages=3501–3510 |pmid=34109022 |doi-access=free }} For the depicted system, both reactions have the same overall [[thermodynamics]] and will produce B and C in equal amounts (50% selectivity) at [[chemical equilibrium]]. Under normal static catalyst operation, only product B can be produced at selectivities greater than 50% and product C is never favored. However, as shown, the application of surface binding dynamics in the form of a square wave at varying [[frequency]] and fixed oscillation [[amplitude]] but varying endpoints exhibits the full range of possible reactant selectivity. In the range of 1-10 [[Hertz]], there exists a small island of parameters for which product C is highly selective; this condition is only accessible via dynamics.{{cite journal |doi=10.26434/chemrxiv.10271090.v1 |author=M.A. Ardagh |author2=M. Shetty |author3=A. Kuznetsov|author4=Q. Zhang |author5=P. Christopher |author6=D.G. Vlachos |author7=O.A. Abdelrahman |author8=P.J. Dauenhauer |title=Catalytic Resonance Theory: Parallel Reaction Pathway Control |journal=ChemRxiv |year=2019|url=https://chemrxiv.org/ndownloader/files/18549938 |doi-access=free }}

[[File:Programmable Catalytic Ratchet with Efficient Operation.gif|thumb|'''Efficient Programmable Catalyst:''' A programmable catalyst oscillating between strong and weak binding states efficiently converts purple molecules, A(g), to gold molecules, B(g)]]

[[File:Programmable Catalytic Ratchet with Efficient Operation.gif|thumb|'''Efficient Programmable Catalyst:''' A programmable catalyst oscillating between strong and weak binding states efficiently converts purple molecules, A(g), to gold molecules, B(g)]]

A programmable catalyst oscillating between strong and weak binding energies exhibits positive scaling between reaction intermediates; B* and A* both weaken and strengthen in binding energy simultaneously. Under strong binding conditions, A* readily reacts over the transition state to form B*. For weaking catalyst binding conditions, B* readily desorbs to form B(g), as A(g) immediately adsorbs as A* to restart the catalytic cycle. An efficient programmable catalyst converts molecules from reactants to products with every oscillation of binding energy of the active site, such that most active sites on the catalyst surface produce a product molecule for every catalytic oscillation cycle. Of key importance is the height of the transition state barrier in the weak-binding catalyst state; a high barrier creates a ratchet mechanism, whereby B* is prohibited from reacting backwards to A*.{{cite journal |doi=10.1021/acscatal.9b01606 |author=M.A. Ardagh |author2=O.A. Abdelrahman |author3=P.J. Dauenhauer |title=Principles of Dynamic Heterogeneous Catalysis: Surface Resonance and Turnover Frequency Response |journal=ACS Catalysis |year=2019|volume=9 |issue=8 |pages=6929–6937 |url=https://pubs.acs.org/doi/10.1021/acscatal.9b01606 }}

A programmable catalyst oscillating between strong and weak binding energies exhibits positive scaling between reaction intermediates; B* and A* both weaken and strengthen in binding energy simultaneously. Under strong binding conditions, A* readily reacts over the transition state to form B*. For weaking catalyst binding conditions, B* readily desorbs to form B(g), as A(g) immediately adsorbs as A* to restart the [[catalytic cycle]]. An efficient programmable catalyst converts molecules from reactants to products with every oscillation of binding energy of the active site, such that most active sites on the catalyst surface produce a product molecule for every catalytic oscillation cycle. Of key importance is the height of the transition state barrier in the weak-binding catalyst state; a high barrier creates a ratchet mechanism, whereby B* is prohibited from reacting backwards to A*.{{cite journal |doi=10.1021/acscatal.9b01606 |author=M.A. Ardagh |author2=O.A. Abdelrahman |author3=P.J. Dauenhauer |title=Principles of Dynamic Heterogeneous Catalysis: Surface Resonance and Turnover Frequency Response |journal=ACS Catalysis |year=2019|volume=9 |issue=8 |pages=6929–6937 |url=https://pubs.acs.org/doi/10.1021/acscatal.9b01606 }}

The efficiency of a programmable catalyst can be determined by the metric of the ''turnover efficiency'' (η_TOE). The turnover efficiency compares the difference between the time-averaged dynamic turnover frequency of the reaction (TOF_dyn) and the steady state turnover frequency (TOF_ss) to the applied catalytic oscillation frequency, ''f''_app.

The efficiency of a programmable catalyst can be determined by the metric of the ''turnover efficiency'' (η_TOE). The turnover efficiency compares the difference between the time-averaged dynamic turnover frequency of the reaction (TOF_dyn) and the steady state turnover frequency (TOF_ss) to the applied catalytic oscillation frequency, ''f''_app.