Configurations Of Intermediates Research Articles

Flame propagation characteristics and gas-phase oxidation of nitrous oxide and propane

Nitrous oxide and fuel blends propellant as one of the substitutes for highly toxic hydrazine are under investigation. This study investigated the flame structure and dynamics of stoichiometric nitrous oxide and propane mixture (N2O/C3H8) by using polymethyl methacrylate (PMMA) tubes of varying inner diameters (5, 10, 15, and 50 mm) and a consistent length (1400 mm). The influence of tube diameter on flame acceleration was analyzed. The results reveal that within the 50-mm diameter tube, the flame propagation speed increased as the flame front moved forward in the tube, achieving a maximum speed of 532 m/s. In the tubes with 5-, 10-, and 15-mm diameters, all three stages—deflagration, transition to detonation, and detonation attenuation—were observed. Notably, the flame acceleration rate and maximum propagation velocity increased with the tube diameter, with the maximum velocities in the 5-, 10-, and 15-mm tubes being 1900, 2060, and 2140 m/s, respectively. The oxidation pathways of C3H8 reacting with N2O were studied using the B3LYP/6–31++G** method based on density functional theory. Thus, the study could determine changes in the configurations of reactants, intermediates, transition states, and products; the characteristics of the potential energy associated with the reaction pathways; and the reaction laws and thermodynamic parameters.

High-temperature resistant BaO-Y2O3 catalysts with different morphologies for NO decomposition and mechanism study

The high-temperature reaction is a common phenomenon in combustion society, and its catalytic response remain a tremendous challenge hampered by the activity and resistance of the catalyst to high temperatures exceeding 1000 ℃. Three distinct forms of BaO-Y2O3 catalysts—nanosphere, nanorod, and rod—were created using a hydrothermal method and high-temperature annealing to enable direct decomposition of NO. To gather reaction-relevant structural and property information for BaO-Y2O3, we combined reactor activity measurements, chemisorption and DFT studies to elucidate NO high-temperature decomposition process and pinpoint the critical role of oxygen vacancy. We have systematically clarified the increasing favorability of NO decomposition on the nano-catalysts (nanospheres and nanorods) at high temperatures is through stable lattice structure, large specific surface areas, high porosity, and active Ba–O–Y bond. Due to the attraction of electrons gathering in vacancies to NO molecules, oxygen vacancies created in situ at high temperatures, as validated by O2-TPD and density functional theory (DFT) calculations, are advantageous for NO adsorption and decomposition. Moreover, N2 formation pathway over Ba-Y2O3(111) structure is revealed by DFT calculations that NO molecules are apt to be caught by active sites, the region of Ba–O–Y, resulting in the production of N2O2 intermediate and its subsequent bond breaking to N2O as well as N2. In situ DRIFTS experiment further confirms the reaction mechanism via the detected adsorbed species, and clarify the significance of NO2− to O2 formation. In a nutshell, the synthetic combustion catalysts are effective in high-temperature environments that contribute to de-NOx combustion, and the insights into the adsorption configurations of reactant and intermediates unlock fundamental understanding for emissions gas chemistry.

Spatially and Temporally Resolved Dynamic Response of Co-Based Composite Interface during the Oxygen Evolution Reaction.

Interfacial interaction dictates the overall catalytic performance and catalytic behavior rules of the composite catalyst. However, understanding of interfacial active sites at the microscopic scale is still limited. Importantly, identifying the dynamic action mechanism of the "real" active site at the interface necessitates nanoscale, high spatial-time-resolved complementary-operando techniques. In this work, a Co3O4 homojunction with a well-defined interface effect is developed as a model system to explore the spatial-correlation dynamic response of the interface toward oxygen evolution reaction. Quasi in situ scanning transmission electron microscopy-electron energy-loss spectroscopy with high spatial resolution visually confirms the size characteristics of the interface effect in the spatial dimension, showing that the activation of active sites originates from strong interfacial electron interactions at a scale of 3 nm. Multiple time-resolved operando spectroscopy techniques explicitly capture dynamic changes in the adsorption behavior for key reaction intermediates. Combined with density functional theory calculations, we reveal that the dynamic adjustment of multiple adsorption configurations of intermediates by highly activated active sites at the interface facilitates the O-O coupling and *OOH deprotonation processes. The dual dynamic regulation mechanism accelerates the kinetics of oxygen evolution and serves as a pivotal factor in promoting the oxygen evolution activity of the composite structure. The resulting composite catalyst (Co-B@Co3O4/Co3O4 NSs) exhibits an approximately 70-fold turnover frequency and 20-fold mass activity than the monomer structure (Co3O4 NSs) and leads to significant activity (η10 ∼257 mV). The visual complementary analysis of multimodal operando/in situ techniques provides us with a powerful platform to advance our fundamental understanding of interfacial structure-activity relationships in composite structured catalysts.

Engineered oxidation states in NiCo2O4@CeO2 nanourchin architectures with abundant oxygen vacancies for enhanced oxygen evolution reaction performance

Sluggish oxygen evolution reaction (OER) as the half reaction of water electrolysis hindered the production of clean hydrogen, necessitates a cost-effective electrocatalyst. Spinel nickel cobaltite (NiCo2O4), characterized by its lower cost, flexibility in oxidation states of cations, and stable spinel structure, holds promise as an OER electrocatalyst. However, there is still room for improvement in terms of its intrinsic electrochemical activity, conductivity, and active surface area. Inspired by the flexible valence states of Ni and Co, in this study, CeO2 was introduced into NiCo2O4 for further electronic structure adjustment. The result was the synthesis of an urchin-like NiCo2O4@CeO2 (NCOC), and the elucidation of its formation mechanisms, expressed conclusively through reaction formulas. NCOC, characterized by an open architecture and a rough surface, ensures rapid mass transportation and charge diffusion. Within NCOC, numerous oxophilic Ce3+ sites with oxygen vacancies construct electron transport pathways, accelerating charge-transfer. This simultaneously induces an increase in the oxidation states and proportions of Ni3+ and Co3+ in NCOC, reinforcing the covalence of Ni–O and Co–O bonds, expediting the ad/desorption of intermediates during OER. The electronic structure variations of NCOC were further verified through density functional theory (DFT) analyses, revealing alterations in adsorption configurations of intermediates and a decrease in adsorption free energies for intermediates on NCOC during OER. In practical terms, NCOC demonstrated a low overpotential of 228 mV at a current density of 10 mA cm−2 under 1 M KOH, maintaining long-term electrochemical stability for 100 h. Overall, this study provides a universal approach for designing highly cost-efficient electrocatalysts for OER.

Electrochemical reduction of CO2 on Cu doped titanium nanotubes—An insight on ethylene selectivity

Electrochemical reduction of CO2 is performed on Cu electrodeposited Ti nanotubes (Cu/TiNT). TiNT is prepared by anodization method followed by electrodeposition of Cu and the CO2 reduction achieved is compared with that of bare electrodes. The comparison between Cu/TiNT and TiNT is done based on the characterization techniques of Scanning Electron Microscopy, X-ray Diffraction, Transmission Electron Microscopy, X-ray Photoelectron Spectroscopy and UV-Diffuse Reflectance Spectroscopy. Electrochemical reduction of CO2 is carried out in an H-type cell with 0.5 M KCl electrolyte, and ethylene, methane, formic acid, CO, hydrogen along with methanol and ethanol are observed as trace products. Among the electrodes studied, maximum Faradaic efficiency (55%) is observed for Cu/TiNT compared to TiNT and bare electrodes. To understand the mechanism of CO2 reduction which produces ethylene on the surface, calculations of first principles are carried out for the Ti nanotubes with Cu deposition on the surface and the binding configurations of various intermediates are studied. The result of first principle calculation shows that the ethylene formation on the Cu deposited surface is favorable than the methane which is in line with the experimental observation.

Theoretical Insights into Enantioselective [3 + 2] Cycloaddition between Cinnamaldehyde and Cyclic N-Sulfonyl Trifluoromethylated Ketimine Catalyzed by N-Heterocyclic Carbene.

The density functional theory (DFT) method was used to investigate the mechanism and the origin of stereoselectivity of N-heterocyclic carbene (NHC)-catalyzed [3 + 2] cycloaddition between enals and cyclic imine N-sulfonyl trifluoromethyl ketimines at the M06-2X/SMD/6-311+G(d,p)//M06-2X/SMD/6-31G (d,p) level. The results show that the favorable reaction path consists of five steps: nucleophilic attack, proton transfer, the formation of the C-C bond, the tautomerism of the enol intermediate, the formation of the five-membered ring, and the regeneration of the catalyst. For the process of proton transfer, the base-assisted reaction can reduce the activation free energy and make the reaction easier to occur compared with the direct proton transfer process. The formation of the C-C bond is the crucial step of stereoselectivity, in which two chiral centers and four configurations of intermediates (RR/RS/SR/SS) were generated. The free energy barriers obtained and the noncovalent interaction analysis confirm that the dominant configuration is SS, becoming the final trans-type product observed in experiment. Furthermore, through the analyses of the conceptual DFT and natural atomic charges, it is revealed that NHC acts as a double catalyst, which can not only increase the nucleophilicity of reactants by Lewis base but also activate the C-H bond and promote the proton transfer process. The understanding of the mechanism obtained in this study should be helpful to the other organic catalytic reactions with high stereoselectivity.

Tuning the Electronic and Steric Interaction at the Atomic Interface for Enhanced Oxygen Evolution.

The two-dimensional surface or one-dimensional interface of heterogeneous catalysts is essential to determine the adsorption strengths and configurations of the reaction intermediates for desired activities. Recently, the development of single-atom catalysts has enabled an atomic-level understanding of catalytic processes. However, it remains obscure whether the conventional concept and mechanism of one-dimensional interface are applicable to zero-dimensional single atoms. In this work, we arranged the locations of single atoms to explore their interfacial interactions for improved oxygen evolution. When iridium single atoms were confined into the lattice of CoOOH, efficient electron transfer between Ir and Co tuned the adsorption strength of oxygenated intermediates. In contrast, atomic iridium species anchored on the surface of CoOOH induced inappreciable modification in electronic structures, whereas steric interactions with key intermediates at its Ir-OH-Co interface played a primary role in reducing its energy barrier toward oxygen evolution.

Photodeprotection Reaction Mechanisms of Caged Species Utilizing a Photochromism Function.

Acetoxy-1,2,2-tri(aryl)ethanone (1) is a novel and visual release-and-report system that contains the photochromic diarylethylene function attached to the photocage dimethoxybenzoin platform. However, the mechanism of 1 cyclization and a subsequent deprotection remains unclear. Here, we use femtosecond and nanosecond transient absorption spectroscopies in combination with density functional theory computations to study the detailed reaction mechanism. The photodeprotection proceeds with competition between pathways initiated by two different configurations of the singlet excited state of 1 (labeled as 11LE and 11CT); the stepwise elimination after cyclization of 11LE constitutes the predominant pathway, whereas the concerted removal of acetic acid after cyclization of 11CT is the minor pathway. These results contribute to a detailed photodeprotection mechanism of 1 and provide new insights into the effect of geometric configurations of intermediates on the photodeprotection pathways. This new information can help in the further development of this type of the photolabile protecting group (PPG) for the protection of biorelevant molecules and in the design of an improved and versatile release-and-report PPG.

Increasing Olefin Metathesis Activity of Silica‐Supported Molybdenum Imido Adamantylidene Complexes through E Ligand σ‐Donation

AbstractMolybdenum imido adamantylidene complexes with different substituents on the imido ligand (dipp=2,6‐diisopropylphenyl, ArF5=C6F5, and tBu) having distinct electron donating abilities were investigated for the metathesis of internal and terminal olefins, for both molecular and silica‐supported species using standardized protocols. Here we show that surface immobilization of these compounds results in dramatically increased activity compared to their molecular counterparts. Additionally, we show that electron withdrawing imido groups increase the activity of the compound towards terminal olefins while they simultaneously decrease the ability to metathesize internal olefins. Furthermore, these systems also show high stability when used as initiators in olefin metathesis, although the species that display higher initial activity deactivate faster than those that show more a more moderate reaction rate at first. Our catalytic studies, augmented by DFT calculations, show that all investigated compounds have a remarkably small energy difference between the trigonal bipyramidal (TBP) and square planar (SP) configurations of the metallacyclobutane intermediates, which has previously been linked to high activity.

Alternative Mechanistic Considerations: Charactering Multiple Reaction Pathways for the Oxygen Evolution Reaction

H2 remains an important chemical precursor in processes such as the Haber-Bosch process to synthesize ammonia and hydrocracking for refining of hydrocarbons and also exists as an alternative fuel for transportation. Currently, 95% of H2 is produced by steam methane reforming, whose byproduct is pollutant CO. Electrolysis is a clean, efficient method run at room temperature to split water into H2and O2. However, electrolysis is not cost-competitive with steam methane reforming, utilizing large amounts of platinum group materials. Computational chemistry can give atomic and electronic levels of understanding of a material by identifying highly active facets of a known material or predicting the catalytic potential of unknown materials. We will model catalysts used in the oxygen evolution reaction, the half-cell reaction requiring the most catalyst and occurring many orders of magnitude slower than the hydrogen evolution reaction. We will focus on the effect of the ensemble: modeling different facets of iridium oxide, characterizing all possible configurations of key reaction intermediates, and incorporating explicit solvation to fully understand the nuances of optimizing a premier catalyst such as IrO2. In particular, we will focus our calculations on two facets: (110), the more thermodynamically stable facet and (001), a potentially more active facet due to the presence of undercoordinated, surface Ir sites. We will compare the reaction profile of the ensemble of key reaction intermediates on the (110) versus the (001) facet and in vacuum versus with solvation. The ensemble of intermediates allows us to explore multiple reaction pathways on the surface that have not been characterized.Figure 1. A schematic summarizing the different isomers found at each reaction step (TOP) and the reaction profile of the oxygen evolution reaction on the (110) facet of iridium oxide (BOTTOM). Figure 1

BN cluster-doped graphdiyne as visible-light assisted metal-free catalysts for conversion CO2 to hydrocarbon fuels

Carbon dioxide electrochemical reduction reaction (CO2RR) under ambient conditions provides an intriguing picture for conversion of CO2 to useful fuels and chemicals. Here by means of density functional theory (DFT) computations, the formation configuration and CO2RR catalytic activity of boron nitrogen cluster-doped graphdiyne (BN-doped GDY) were systematically investigated. The band structure and optical adsorption spectra reveal that BN-doped GDY exhibits semiconductor with the band gap of 0.902 eV and shows photothermal effect under visible and even infrared light irradiation. The BN-doped GDY could act as a hot spot to enhance CO2RR. The adsorption configurations of various reaction intermediates indicate that boron atoms are active sites, which can be further confirmed by charge analysis. Based on thermodynamic analysis, the reaction pathways and onset potentials were studied as compared with Cu(111) surface. For the production of CO, the onset potential for BN-doped GDY (−1.06 V) is higher than that for Cu(111) surface. While for the reduction of CO2 to HCOOH, CH4, CH3OH, and C2H4 on BN-doped GDY, the onset potentials are lower than that on Cu(111) surface, which are −0.57 V, −0.62 V, −0.57 V, and −0.82 V, respectively. Moreover, the onset potential of competitive hydrogen evolution reaction on BN-doped GDY is high to −0.82 V, which shows us a good selectivity towards to CO2RR rather than HER. Our results may pave a new avenue for the conversion of CO2 into high-value fuels and chemicals.

Selective hydrogenation of p-chloronitrobenzene on nanosized gold clusters: A theoretical study

The selective hydrogenation of p-chloronitrobenzene on Au13 and Au55 nanoclusters has been systematically studied by density functional theory (DFT), allowing for a comparison with Au20 nanocluster. All possible adsorption configurations of relevant intermediates are identified. The adsorption energy of all species exhibit the following trend: Au13 > Au20 > Au55. The detailed reaction barriers show that Au55 nanocluster has the least hydrogenation reaction barrier of the rate-limiting step, whereas the dechlorination reaction is least likely to cause on Au55 nanocluster. These observations suggest that the 55-atom gold cluster is predicated to be the appropriate catalyst for practical application.

Insights into the mechanism of acetic acid hydrogenation to ethanol on Cu(111) surface

Density functional theory (DFT) calculations were employed to theoretically explain the reaction mechanism of acetic acid hydrogenation to ethanol on Cu catalyst. The activation barriers of key elementary steps and the adsorption configurations of key intermediates involved in acetic acid hydrogenation on Cu(111) surface were investigated. The results indicated that the direct dissociation of acetic acid to acetyl (CH3COOH→CH3CO+OH) is the rate-determined step. The activation barrier of acetic acid scission to acetyl and the adsorption energy of acetic acid are two descriptors which could determine the conversion of acetic acid. The descriptors might have effects on the ethanol selectivity including: the adsorption energy of acetaldehyde and the activation barriers for OH bond formation of C2-oxygenates (CH3CO+H→CH3COH, CH3CHO+H→CH3CHOH and CH3CH2O+H→CH3CH2OH). These proposed descriptors could be used as references to design new Cu-based catalysts that have excellent catalytic performance.

On-line attenuated total reflection infrared (ATR-IR) spectroscopy combined with advanced chemometrics for investigating the synthesis process of 3,5-diamino-1,2,4-triazole

The synthesis process of 3,5-diamino-1,2,4-triazole (DAT) was investigated by on-line attenuated total reflection infrared (ATR-IR) spectroscopy combined with advanced chemometrics method. The principal component analysis (PCA) was used to analyze the IR spectra matrix, which was in order to obtain orthonormal column and the number of principal components. Then the pure IR spectrum of every substance was obtained by mutual information least dependent component analysis (MILCA). The possible synthesis mechanism of DAT was deducted based on the changes of functional groups in the IR spectra. The geometric configurations of intermediates were optimized with the density functional theory (DFT) at B3LYP/6-311G*(d, p) level, and the vibrational frequencies were calculated simultaneously. The results by MILCA method agree well with quantum chemical calculation method, thus which demonstrated the reliability of MILCA. The present study proves that on-line ATR-IR spectroscopy combined with advanced chemometrics method can be applied to study the chemical synthesis mechanism and provide a strong technical support for the research and development of process analytical technology (PAT).

Theoretical investigation on the dehydrogenation mechanism of CH3OH on Cu (100) surface

Periodic DFT calculations have been employed to investigate the adsorption and dissociation mechanism of CH3OH on Cu (100) surface. For the adsorption, all possible adsorption configurations of relevant intermediates are identified. It is found that CH3OH and CHOH prefer to adsorb on the top sites, CH2OH and CO adsorb preferentially on the bridge sites, while CH3O, CH2O, CHO, COH and H occupy the hollow sites. Methanol and formaldehyde are weakly bound on the Cu (100) surface and are easily desorbed. CH2OH, CH3O, CHOH, CO, CHO, COH and H are adsorbed strongly on the surface. Additionally, four possible pathways of CH3OH dissociation initiated through the activation of OH and CH bonds, have been proposed and studied systematically. It is revealed that the breaking of the HO bond is more favorable for CH3OH, CH2OH and CHOH species. Consequently, the pathway (CH3OHCH3OCH2OCHOCO) is the most probable dehydrogenation route, where the highest energy barrier of CH3O dissociation makes it to be the rate-determining step of the whole dehydrogenation reaction.

Metal-Oxygen Bond Ionicity as an Efficient Descriptor for Doped NiOOH Photocatalytic Activity.

The computational design of solid catalysts has become a very "hot" field during the last decades, especially with the recent increase in computational tool performance. However, theoretical techniques are still very time demanding because they require the consideration of many adsorption configurations of the reaction intermediates on the surface. Herein, we propose to use the metal-oxygen (M-O) bond ionicity as a descriptor for the photocatalytic activity of one of the best catalysts for the oxygen evolution reaction (OER). Ionicity is a bulk property and thus carries the advantage of being easily obtainable from a simple Bader charge analysis by using density functional theory (DFT). We will show that this criterion can be used successfully to design efficient dopants for NiOOH material. This catalyst is known to exhibit interesting photoelectrochemical properties for OER if it is doped with specific transition metals. Finally, we demonstrate that other electronic properties that relate to bulk calculation, such as oxidation states and density of states, are not alone sufficient to explain the photocatalytic activity of the material. Thus, M-O bond ionicity attracts significant interest compared with other bulk observables obtained by using DFT computations.

Theoretical study of NH3 decomposition on Pd-Cu (1 1 1) and Cu-Pd (1 1 1) surfaces: A comparison with clean Pd (1 1 1) and Cu (1 1 1)

The adsorption and successive dehydrogenation mechanisms of NH3 on Pd-Cu (111) and Cu-Pd (111) surfaces (the Pd atoms substitution of the first and second layers of Cu (111) surfaces) have been systematically investigated by density functional theory (DFT) method with a periodic slab model. All possible adsorption configurations of relevant intermediates on Pd-Cu (111) and Cu-Pd (111) surfaces are identified. It is revealed that the adsorption configurations and corresponding adsorption energies of adsorbates are slightly changed on Pd-Cu (111) and Cu-Pd (111) surfaces. The adsorption energies of NHx(x=0–3) species exhibit the following trend: NH3<NH2<NH<N. Then, the minimum energy path for the complete dehydrogenation of NH3 into adsorbed N and H is identified to explore the dehydrogenation mechanisms on different surfaces. The highest energy barrier and reaction energy on Pd-Cu (111) surface are greatly reduced to 1.56 and 0.99eV, implying that the complete dehydrogenation of NH3 on Pd-Cu (111) surface is favorable both kinetically and thermodynamically, namely, the doped-Pd atoms in the first layer are the reaction active center. Compared to that on clean Pd (111) and Cu (111) surfaces, it is found that the synergistic effect exits in different layers of catalyst surfaces. The calculated results show that the layer-substituted Pd atoms on the surface of Cu catalysts exhibit a better catalytic activity for NH3 dehydrogenation compared to the clean Cu (111) surface.

Density functional theory study of C₂F₅I synthesis over activated carbon catalyst.

Quantum chemistry calculations based on the density functional theory (DFT) are carried out to investigate the reaction mechanism of C2F5I synthesis catalyzed by activated carbon. The possible adsorption configurations of fluorocarbon intermediates are analyzed carefully. Also, the related transition states and reaction pathway are analyzed. According to calculation, firstly, the dehydrofluorination of C2HF5, as the rate-determining step, is catalyzed by the carboxyl acid groups. Secondly, the tetrafluoroethylidene radicals disproportionate on graphite (001) surface instead of rearrangement or dimerization. Next, the fluorine abstractions between fluorocarbon intermediates over graphite (001) surfaces proceed successfully. Finally, the desorbed pentafluoroethyl abstracts iodine atom from molecular iodine spontaneously to afford C2F5I. In adition, our calculations reveal that the carbon deposit in experiment is caused by the fluorine abstraction from fluoroethinyl. The suggested mechanism corresponds with our calculations and available experiments.

A density functional theory study of methanol dehydrogenation on the PtPd3(111) surface

Platinum (Pt)-based catalyst has been widely used as the catalyst in direct methanol fuel cells. This study aimed at determining the favorable pathway for methanol (CH3OH) dehydrogenation on the PtPd3(111) surface through the periodic density functional theory (DFT) calculation. The calculation evaluated the stable adsorption configurations of the possible intermediates produced from the successive dehydrogenation of methanol through C–H and O–H bond scission. The results showed that CH3OH, CH2OH, CH3O and CHO preferred to locate at the top site, COH, CO and H preferred to adsorb on the face centered cubic (fcc) site, while CH2O and CHOH would choose the bridge site. Both CH3OH and CH2O were bonded weakly on the PtPd3(111) surface due to their closed-shell electronic configurations. The other intermediate species were interacted strongly with the surface. The energy barriers in four possible pathways via initial breakage of O–H or C–H bond were calculated. By comparing the energy changes in the potential energy surface, the initial O–H scission of CH3OH as the most favorable reaction pathway was determined. The activation barrier by this pathway was only 0.955 eV. The dehydrogenation mechanism from CH3OH to CO via breaking O–H bond was derived as CH3OH → CH3O → CH2O → CHO → CO. The first dissociation step, CH3OH into CH3O and H was identified as the rate-limiting step. The theoretical results indicated that the proposed pathway for methanol dehydrogenation on PtPd3(111) surface was energetically favorable, and verified that the PtPd3 catalyst with Pt monolayer is a good candidate for methanol dissociation.

CO oxidation catalysed by Pd-based bimetallic nanoalloys.

Density functional theory based global geometry optimization has been used to demonstrate the crucial influence of the geometry of the catalytic cluster on the energy barriers for the CO oxidation reaction over Pd-based bimetallic nanoalloys. We show that dramatic geometry change between the reaction intermediates can lead to very high energy barriers and thus be prohibitive for the whole process. This introduces challenges for both the design of new catalysts, and theoretical methods employed. On the theory side, a careful choice of geometric configurations of all reaction intermediates is crucial for an adequate description of a possible reaction path. From the point of view of the catalyst design, the cluster geometry can be controlled by adjusting the level of interaction between the cluster and the dopant metal, as well as between the adsorbate molecules and the catalyst cluster by mixing different metals in a single nanoalloy particle. We show that substitution of a Pd atom in the Pd5 cluster with a single Ag atom to form Pd4Ag1 leads to a potential improvement of the catalytic properties of the cluster for the CO oxidation reaction. On the other hand, a single Au atom does not enhance the properties of the catalyst, which is attributed to a weaker hybridization between the cluster's constituent metals and the adsorbate molecules. Such flexibility of properties of bimetallic nanoalloy clusters illustrates the possibility of fine-tuning, which might be used for design of novel efficient catalytic materials.