Alcohol Oxidation Reactions Research Articles

Abundant Exterior/Interior Active Sites Enable Three-Dimensional PdPtBiTe Dumbbells C-C Cleavage Electrocatalysts for Actual Alcohol Fuel Cells.

Developing high-activity electrocatalysts is of great significance for the commercialization of direct alcohol fuel cells (DAFCs), but it still faces challenges. Herein, three-dimensional (3D) porous PdPtBiTe dumbbells (DBs) were successfully fabricated via the visible photoassisted method. The alloying effect, defect-rich surface/interface and nanoscale cavity, and open pores make the 3D PdPtBiTe DBs a comprehensive and remarkable electrocatalyst for the C1-C3 alcohol (ethanol, ethylene glycol, glycerol, and methanol) oxidation reaction (EOR, EGOR, GOR, and MOR, respectively) in an alkaline electrolyte, and the results of in situ Fourier transform infrared spectra revealed a superior C-C bond cleavage ability. The 3D PdPtBiTe DBs exhibit ultrahigh EOR, EGOR, GOR, and MOR mass activities of 25.4, 23.2, 16.8, and 18.3 A mgPd + Pt-1, respectively, considerably surpassing those of the commercial Pt/C and Pd/C. Moreover, the mass peak power densities of 3D PdPtBiTe DBs in actual ethanol, ethylene glycol, glycerol, or methanol fuel cells increase to 409.5, 501.5, 558.0, or 601.3 mW mgPd + Pt-1 in O2, respectively. This study provides a new class of multimetallic nanomaterials as state-of-the-art multifunctional anode electrocatalysts for actual DAFCs.

Evaluation of the Activity of Potassium Dodecatungstate Salts in Alcohol Oxidation Reactions: Cobalt(II), Cobalt(III), or Silicon(IV) as the Heteroatom

Evaluation of the Activity of Potassium Dodecatungstate Salts in Alcohol Oxidation Reactions: Cobalt(II), Cobalt(III), or Silicon(IV) as the Heteroatom

A DFT investigation of the catalytic oxidation of benzyl alcohol using graphene oxide.

Metal-free heterogeneous materials have attracted great interest due to their potential to facilitate various organic transformations in line with circular economy and green chemistry principles. Among various 2D materials, graphene oxide (GO) is considered an attractive material for numerous applications in physics, chemistry, biology, material sciences, and catalysis. Furthermore, graphene-based catalysts exhibit good catalytic activity toward the selective oxidation of benzyl alcohol to benzaldehyde or benzoic acid under eco-friendly conditions. In this regard, a theoretical investigation was carried out to study both catalytic oxidation reaction pathways (i.e., benzyl alcohols to aldehyde and to benzoic acid) using GO as an eco-friendly and metal-free catalyst. In this study, we report a theoretical investigation at the B3LYP/6-31G level to better understand the oxidation of benzyl alcohol using GO as a metal-free catalyst. The possible bond formation was investigated using the global and local reactivity indexes derived from Fukui functions. Furthermore, we performed a non-covalent interaction (NCI) analysis to unveil the stability and the interaction nature between both reagents and GO surface. The effect of the solvent on the oxidation efficiency was also performed and the results indicate that the solvent significantly affects the decrease of reactivity by increasing the activation barriers through oxidation reactions of benzyl alcohol. Additionally, the electron localization function (ELF) analysis was performed for all intermediates showing the ionic nature of the studied epoxide structure of GO and rules out any type of covalent interaction during the oxidation reaction of benzyl alcohol. All these obtained results are in good agreement with experimental observations and reveal that the epoxide functions on the graphene surface promote an excellent catalyst turnover.

Au/Pt Bimetallic Nanowires with Stepped Pt Sites for Enhanced C-C Cleavage in C2+ Alcohol Electro-oxidation Reactions.

Efficient C-C bond cleavage and oxidation of alcohols to CO2 is the key to developing highly efficient alcohol fuel cells for renewable energy applications. In this work, we report the synthesis of core/shell Au/Pt nanowires (NWs) with stepped Pt clusters deposited along the ultrathin (2.3 nm) stepped Au NWs as an active catalyst to effectively oxidize alcohols to CO2. The catalytic oxidation reaction is dependent on the Au/Pt ratios, and the Au1.0/Pt0.2 NWs have the largest percentage (∼75%) of stepped Au/Pt sites and show the highest activity for ethanol electro-oxidation, reaching an unprecedented 196.9 A/mgPt (32.5 A/mgPt+Au). This NW catalyst is also active in catalyzing the oxidation of other primary alcohols, such as methanol, n-propanol, and ethylene glycol. In situ X-ray absorption spectroscopy and infrared spectroscopy are used to characterize the catalyst structure and to identify key reaction intermediates, providing concrete evidence that the synergy between the low-coordinated Pt sites and the stepped Au NWs is essential to catalyze the alcohol oxidation reaction, which is further supported by DFT calculations that the C-C bond cleavage is indeed enhanced on the undercoordinated Pt-Au surface. Our study provides important evidence that a core/shell structure with stepped core/shell sites is essential to enhance electrochemical oxidation of alcohols and will also be central to understanding electro-oxidation reactions and to the future development of highly efficient direct alcohol fuel cells for renewable energy applications.

Hydrophobic and visible-light responsive TiO2 as an efficient photocatalyst for promoting hydrogen peroxide production in a two-phase system

Photocatalytic synthesis of hydrogen peroxide (H2O2) coupled with benzyl alcohol (BA) oxidation reaction is preferred based on the economic consideration. Herein, we developed a hydrophobic TiO2 material (DNOPA-TiO2), co-modified with 2,3-dihydroxynaphthalene (2,3-DN) and octadecylphosphonic acid (OPA), which enables H2O2 synthesis under visible-light-irradiation in a two-phase system consisting of BA and water. This system allows the separation of generated H2O2 in the aqueous phase from benzaldehyde (BAL), the product of BA oxidation, present in the organic phase. The hydrophobic DN2OPA2-TiO2 exhibited higher and more stable H2O2 production (3522 μmol L−1) over an 8-hour reaction under visible light (λ > 450 nm). The addition of 2,3-DN facilitates visible light harvesting and donates electrons to TiO2 through the formation of charge-transfer complexes, which promotes the O2 reduction reaction (ORR) and improves H2O2 production. Moreover, the remarkable stability of DN2OPA2-TiO2 is originated from the hydrophobic nature of the catalysts thanks to OPA modification. This modification allows TiO2 to exist in the organic phase with better dispersion, inhibiting the decomposition of H2O2 resulting from direct contact between produced H2O2 and TiO2.

MOFs as Versatile Catalysts: Synthesis Strategies and Applications in Value-Added Compound Production.

Catalysts played a crucial role in advancing modern human civilization, from ancient times to the industrial revolution. Due to high cost and limited availability of traditional catalysts, there is a need to develop cost-effective, high-activity, and nonprecious metal-based electrocatalysts. Metal-organic frameworks (MOFs) have emerged as an ideal candidate for heterogeneous catalysis due to their physicochemical properties, hybrid inorganic/organic structures, uncoordinated metal sites, and accessible organic sections. MOFs are high nanoporous crystalline materials that can be used as catalysts to facilitate polymerization reactions. Their chemical and structural diversity make them effective for various reactions compared to traditional catalysts. MOFs have been applied in gas storage and separation, ion-exchange, drug delivery, luminescence, sensing, nanofilters, water purification, and catalysis. The review focuses on MOF-enabled heterogeneous catalysis for value-added compound production, including alcohol oxidation, olefin oligomerization, and polymerization reactions. MOFs offer tunable porosity, high spatial density, and single-crystal XRD control over catalyst properties. In this review, MOFs were focused on reactions of CO2 fixation, CO2 reduction, and photoelectrochemical water splitting. Overall, MOFs have great potential as versatile catalysts for diverse applications in the future.

Further revealing reaction mechanism on the oxidation behavior of the vanillyl alcohol

Theoretical investigation on the oxidation reaction of vanillyl alcohol is accomplished by density functional theory. The three oxidation reaction pathways were identified, and the three reactive sites on the vanillyl alcohol are H on phenolic hydroxyl group, H on hydroxymethyl group, and H on methoxyl group. Theoretical calculation and analysis were carried out about the twenty-nine possible reaction channels. The potential energy surface information of every reaction channels was obtained at the B3LYP/6–311 + G(d,p) level, including geometry structure optimization and frequency calculation of the stationary point. The oxygen reaction mechanism of vanillyl alcohol is further revealed in detail at molecular and atomic levels. The calculation results show that the H on phenolic hydroxyl group is easier to be oxidized to phenoxy radical among three reactive sites. Vanillin can produce vanillyl alcohol through a reversible process. The reaction channel of addition by oxygen on one para-position of quinone structure of phenoxy radical is more kinetically favorable than that of the two ortho-positions. Revealing the oxidation mechanism of vanillyl alcohol will provide a new understanding of the catalytic oxidation of lignin model materials and a theoretical basis for the process optimization of efficient utilization of biomass energy.

Two-step synthesis and oxidizing power assessment of novel pyrylium

Photoredox catalysis is a relatively new concept, and it involves the absorption of light for more productive use of lower energy radiation and to catalyze selective reactions. Traditionally, catalysts used for oxidation or reduction reactions were metal catalysts, such as iridium. However, these metal catalysts are not environmentally friendly and are expensive, prompting the use of organic catalysts. Pyrylium salt, an organic catalyst, can be used as a catalyst. However, the oxidizing ability of basic pyrylium is not that good and can still be improved. In this project, a pyrylium salt with substituents that include fluorine and chlorine (halogens) was synthesized to boost its oxidizing ability in an alcohol oxidation reaction due to its electron-withdrawing groups. Despite unsuccessful oxidation, there is still much research to prove that it can substitute for metal catalysts.

Continuous-Flow Chemical Synthesis for Sub-2 nm Ultra-Multielement Alloy Nanoparticles Consisting of Group IV to XV Elements.

Multielement alloy nanoparticles have attracted much attention due to their attractive catalytic properties derived from the multiple interactions of adjacent multielement atoms. However, mixing multiple elements in ultrasmall nanoparticles from a wide range of elements on the periodic table is still challenging because the elements have different properties and miscibility. Herein, we developed a benchtop 4-way flow reactor for chemical synthesis of ultra-multielement alloy (UMEA) nanoparticles composed of d-block and p-block elements. BiCoCuFeGaInIrNiPdPtRhRuSbSnTi 15-element alloy nanoparticles composed of group IV to XV elements were synthesized by sequential injection of metal precursors using the reactor. This methodology realized the formation of UMEA nanoparticles at low temperature (66 °C), resulting in a 1.9 nm ultrasmall average particle size. The UMEA nanoparticles have high durability and activity for electrochemical alcohol oxidation reactions and high tolerance to CO poisoning. These results suggest that the multiple interactions of UMEA efficiently promote the multistep alcohol oxidation reaction.

Milestones of Electrocatalyst Development for Direct Alcohol Fuel Cells

AbstractWith increasing energy demands and environmental issues, renewable energy‐related conversion systems have gained significant attention as a potential substitute for traditional fossil fuel‐based energy technologies. First introduced by S.W.Grove in 1838, fuel cells have been extensively developed into many different types, and direct alcohol fuel cells (DAFCs) are of interest as a potential power source because of their large power density, quick start, simplicity, and nearly zero emission. However, the high cost and poor catalytic efficiency of current catalysts are primary barriers to commercializing DAFCs. Designing advanced nanocatalysts for both anode and cathode electrodes is of crucial importance for practical DAFC development; however, a brief evaluation of current progress in electrocatalyst development for the alcohol oxidation reaction (AOR) and oxygen reduction reaction (ORR) is still very little. Herein, recent advances in fuel cell catalysts, mainly focusing on several most active areas (i.e., Pt‐ and Pt‐free‐based catalysts, metal‐free carbon, carbon‐based nonprecious metal composites) are concisely summarized. Also, challenges and prospects for DAFCs are highlighted to supply a comprehensive view for further designing high‐performance DAFC catalysts.

Engineering Lattice Planes of NiCo-LDH Ultrathin Sheets for Boosting Methanol/Ethanol Oxidation Performance.

Alcohol oxidation reactions are known to be significant in the advancement of sustainable, renewable energy sources. Searching for catalytic materials with powerful, reliable, and economic performance is of great importance. Due to their excellent intrinsic performance, outstanding stability, and inexpensiveness, ultrathin layered double hydroxides (LDHs) are considered to be competitive electrocatalysts. However, the electrocatalytic property of ultrathin LDHs is still confined by the predominant exposure of the (003) basal plane. Hence, we have engineered active edge facets in ultrathin NiCo-LDHs, which possess abundant oxygen vacancies (VO), by a facile one-step strategy. Experimental results show that NiCo-LDH-E synthesized in ethanol demonstrates an ultrathin structure, rich oxygen vacancies, and more active facets, exhibiting a higher electrochemical active area of 3.25 cm2, which is 1.18 times that of NiCo-LDH-W (2.75 cm2). In addition, the current density of NiCo-LDH-E in methanol and ethanol oxidation reactions could reach 159.5 and 136.3 mA cm-2, which are 2.8 and 1.7 times that of NiCo-LDH-W, respectively.

Improved electrocatalytic performance of Ni nano pebbles decorated 2D Fe based MXene nanosheets for direct alcohol (methanol, ethanol and ethylene glycol) fuel cell application

In this work, we report the solid-state reaction-assisted synthesis of the iron-based MAX phase compound (Fe3AlC2 MAX; where M- metal, A- aluminum, and X- carbide), which is solvothermal etched and exfoliated to yield 2D iron (Fe)-MXene. The nanosheet-like morphology of the Fe-MXene is confirmed via TEM and SEM analysis. The 2D Fe-MXene nanosheets are further decorated with nickel (Ni) nano pebbles through the simple electrodeposition technique on a screen-printed carbon electrode (Ni@FC/SPCE). The electrode displays a peak mass activity of 525.5, 742.8, and 910.2 mA/mg for methanol oxidation reaction (MOR), ethanol oxidation reaction (EOR), and ethylene–glycol oxidation reaction (EgOR), respectively. The Ni nano pebbles have excellent electrocatalytic activity owing to their multiple oxidation states (Ni2+/Ni3+) and catalytic active sites which enhance the alcohol oxidation reaction while the metallic sites of the Fe3C2 nanosheets contribute to high electrical conductivity and stability of the electrode. The as-fabricated Ni@FC/SPCE electrode exhibits high stability with outstanding capacity retention of ∼ 88%, ∼95%, and ∼ 75% for MOR, EOR, and EgOR after 10000 s of chronoamperometry analysis. This performance of the Ni@FC/SPCE as a non-noble, cost-effective, and stable nano-catalyst with excellent anti-carbon monoxide (anti-CO) poisoning properties proves it an ideal platform for DAFC applications.

Ti doped CeO2 nanosheets supported Pd catalyst for alcohol oxidation: Catalysis of interfacial sites

AbstractThe oxidation of alcohols is a significant chemical reaction, and the efficient oxidation of alcohols over heterogeneous catalysts using oxygen as oxidant has attracted much attention in recent years. Among them, Pd/CeO2 exhibits excellent alcohol oxidation performance. However, the structure-activity relationship between the catalyst's structure and its catalytic performance for alcohol oxidation is still not clearly understood. This study involved the preparation of CeO2 nanosheets with different concentrations of surface oxygen vacancies (Ov) and their subsequent loading with Pd to explore their catalytic performance for alcohol oxidation. The findings obtained through XPS, Raman, and XAS indicated a positive correlation between the surface Ov concentration of CeO2 as well as the ratio of Pd2+ fraction. The alcohol oxidation results and structure-performance relationship studies showed that there was a good linear relationship between the Pd2+ ratio as well as the surface Ce3+ concentration and the TOF of benzyl alcohol oxidation reaction, respectively. And the interfacial site (Pd–O–Ce) formed by Pd and CeO2 was the main catalytic site for this type of alcohol oxidation catalysts. This study contributes to the understanding of the catalytic role of interfacial sites in metal and oxide support for the development of better alcohol oxidation catalysts.

Understanding the Oxidative Properties of Nickel Oxyhydroxide in Alcohol Oxidation Reactions.

The NiOOH electrode is commonly used in electrochemical alcohol oxidations. Yet understanding the reaction mechanism is far from trivial. In many cases, the difficulty lies in the decoupling of the overlapping influence of chemical and electrochemical factors that not only govern the reaction pathway but also the crystal structure of the in situ formed oxyhydroxide. Here, we use a different approach to understand this system: we start with synthesizing pure forms of the two oxyhydroxides, β-NiOOH and γ-NiOOH. Then, using the oxidative dehydrogenation of three typical alcohols as the model reactions, we examine the reactivity and selectivity of each oxyhydroxide. While solvent has a clear effect on the reaction rate of β-NiOOH, the observed selectivity was found to be unaffected and remained over 95% for the dehydrogenation of both primary and secondary alcohols to aldehydes and ketones, respectively. Yet, high concentration of OH- in aqueous solvent promoted the preferential conversion of benzyl alcohol to benzoic acid. Thus, the formation of carboxylic compounds in the electrochemical oxidation without alkaline electrolyte is more likely to follow the direct electrochemical oxidation pathway. Overoxidation of NiOOH from the β- to γ-phase will affect the selectivity but not the reactivity with a sustained >95% conversion. The mechanistic examinations comprising kinetic isotope effects, Hammett analysis, and spin trapping studies reveal that benzyl alcohol is oxidatively dehydrogenated to benzaldehyde via two consecutive hydrogen atom transfer steps. This work offers the unique oxidative and catalytic properties of NiOOH in alcohol oxidation reactions, shedding light on the mechanistic understanding of the electrochemical alcohol conversion using NiOOH-based electrodes.

The role of AgNPs in selective oxidation of benzyl alcohol in vapor phase using morphologically tailored MnO2 nanorods in the presence of air

Vapor phase benzyl alcohol (BnOH) oxidation reaction is investigated over a pre–synthesised morphologically designed shape controlled spherical silver nanoparticles (AgNPs) decorated on manganese oxide nanorods (α–MnO2NRs) in the presence of air. The combination of silver nanoparticles and the α–MnO2NRs interface enabled the increased oxygen vacancies (Ov) and exhibited the strong metal–support interactions (SMSI) in surface oxygen activation. The effect of Ag loadings is significant and the optimal 1 wt% Ag loaded catalyst (1Ag/MnO2NRs) showed excellent performance in benzyl alcohol oxidation due to high adsorption capacity, enhanced oxygen vacancies and red–ox properties. The DFT calculations confirmed that the high BnOH surface adsorption was exhibited over Ag modified MnO2NRs than the bare α–MnO2NRs. The optimized 1Ag/α–MnO2NRs catalytic system achieved 2.6 fold higher activity compared to bare α–MnO2NRs. These results provided novel insights on the rational design of shape dependent metal/metal oxide based heterogeneous catalysts.

Strain-Induced Porous Pd@PdPt Core/Shell Nanocubes as Effective All-in-One Electrocatalysts toward Multialcohol Oxidation

Constructing an appealing architecture is of great significance to improving the electrocatalytic activity and stability of Pt-based nanocatalysts. In this work, we successfully synthesized porous Pd@PdPt core/shell nanocrystals via a facile one-pot method, which possess several architectural and compositional advantages, involving porous outer, ultrathin branches, an open mesoporous skeleton, a core/shell structure, and an alloyed composition. These morphological features and the synergistic effect between different components in the alloy endow the Pd@PdPt nanostructures with abundant active sites, effective mass transfer, strain in the particle, and the electronic coupling effect. The Pd@PdPt nanoalloy therefore exhibits excellent electrocatalytic performances in alcohol oxidation reactions. Impressively, the Pd5Pt4 nanocubes exhibit a higher mass/specific activity of 3.225 A mgPt+Pd–1/34.49 A m–2 for the ethanol oxidation reaction, which is even 4.00-/2.39-fold as high as that of commercial Pt/C. Moreover, the Pd5Pt4 nanocubes also show a superior mass activity of 2.824 A mgPt+Pd–1/37.66 A m–2 toward the methanol oxidation reaction, which is up to 4.20/2.40 times that of the commercial Pt/C. The Pd@PdPt also has enhanced electrocatalytic stability. More importantly, the porous Pt5Pd4 nanocubes still demonstrate superior electrocatalytic activities of 0.259, 1.19, 2.65, and 2.76 A mgPt+Pd–1 for the oxidation of glucose, isopropyl alcohol, glycerol, and ethylene glycol, respectively. We therefore believe that these universal electrocatalysts have the potential to promote practical applications in fuel cells.

Theoretical Study on the Mechanisms, Kinetics, and Toxicity Evaluation of OH-Initiated Atmospheric Oxidation Reactions of Coniferyl Alcohol

In this paper, we investigated the mechanisms, kinetics, and toxicity evaluation of the OH-initiated reaction of coniferyl alcohol (4-(3-hydroxy-1-propenyl)-2-methoxyphenol) in the atmosphere using theoretical calculations. The initial reaction of coniferyl alcohol with OH radicals had two pathways, H-abstraction and OH-addition reactions. The total reaction rate constants were 2.32 × 10−9 cm3 molecule−1 s−1 (in gas-phase) and 9.44 × 109 s−1 M−1 (in liquid-phase) for the preliminary reactions of coniferyl alcohol with OH radicals at 298 K, respectively, and the half-lives of the total reaction (including all initial H-abstraction and OH-addition reactions) of coniferyl alcohol with OH radical in the atmosphere, urban and remote clouds were 8.3 × 10−2 h, 5.83 × 103 h and 9.27 × 102 h, respectively. The temperature had a strong and positive influence on the initial reaction rate constant. The branching ratios of H-abstraction and OH-addition reactions were 3.68% and 97.69%, respectively, making the OH-addition reactions become dominant reactions. The ecotoxicity evaluation revealed that the toxicity levels of coniferyl alcohol and its products were similar and non-toxic. However, all these products have developmental toxicity, with most of them having no mutagenicity. Therefore, further attention should be paid to the oxidation process and product toxicity evaluation of coniferyl alcohol in the atmosphere.

Activable Ru-PdRu nanosheets with heterogeneous interface for High-efficiency alcohol oxidation reaction

Fabricating 2D nanomaterials with heterogeneous structure is a feasible way to improve catalytic performance owing to its large surface area and tunable electron structure. However, such a category has not been widely reported in the field of alcohol oxidation reaction (AOR). In this work, we reported a new type of heterostructure nanosheet with Ru nanoparticles decorated around the edge of PdRu nanosheets (Ru-PdRu HNSs). Particularly, strong electronic interaction and sufficient active sites attributed to the construction of heterogeneous interface, is the key to the superior electrocatalytic behavior of Ru-PdRu HNSs towards methanol oxidation reaction (MOR), ethylene glycol oxidation reaction (EGOR), and glycerol oxidation reaction (GOR). Remarkably, owing to the enhanced electron transfer brought by the introduction of the Ru-PdRu heterogeneous interface, these novel nanosheets are highly durable. Apart from being able to maintain the highest current density after 4000 s chronoamperometry test, Ru-PdRu HNSs can be reactivated with negligible activity loss in MOR and GOR test after four consecutive i-t experiments. Impressively, in the EGOR test, after reactivation, the current density is step-wisely increased, making it one of the best AOR electrocatalysts.

Tailoring defects in In2S3/Zn0.3Cd0.7S heterojunctions for efficient photocatalytic CO2 conversion

Defect engineering is a highly effective approach to regulate the electronic structure of the catalyst surface, widely employed in the field of photocatalytic energy conversion. In this study, we have successfully synthesized a novel dual-defective In2S3/Zn0.3Cd0.7S (IS/ZCS) heterojunction structure via a self-assembly method, composed of Zn-vacancy-rich Zn0.3Cd0.7S (ZCS) and S-vacancy-rich In2S3 (IS). Under visible light illumination, 3% IS/ZCS sample exhibits remarkable photocatalytic performance in the synergistic reaction of CO2 reduction and 4-chlorobenzyl alcohol (Cl-PhCH2OH) oxidation with the CO yield significantly improved by a factor of 3.5 and 51 compared to that of ZCS and IS, respectively. The combined experimental data and theoretical calculations demonstrate that the dual-defective structure and Z-scheme transfer mode are the key factors behind the enhanced photocatalytic activity, providing more active sites and effectively improving the utilization of photogenerated charge carriers (PCCs). Moreover, the reaction pathway and catalytic mechanism of photocatalytic CO2 reduction were elucidated by the in-situ FTIR technique combined with DFT calculations, monitoring the intermediate and final products during the reaction period. Our results provide a powerful example of designing novel heterojunction photocatalysts with high activity and accelerating the separation of PCCs, with broad implications for the development of efficient photocatalytic systems.

From AuPd Nanoparticle Alloys towards Core‐Shell Motifs with Enhanced Alcohol Oxidation Activity

AbstractThe best activity of bimetallic AuPd nanoparticles for alcohol oxidation reaction is usually achieved by adjusting the Au/Pd molar ratio. Herein, alloy AuPd nanoparticles of ∼2.5–3.5 nm, ranging from Au‐rich to Pd‐rich compositions, were synthesized through a sol‐immobilization method. A calcination step under air conditions caused an increase in size up to 5.5 nm, but also driven the segregation of Pd to the surface, which generated an Au rich core with Pd on the shell. At high Pd content, the shell structure is formed by PdO. The catalytic activity of Pd‐rich samples (1 : 1, 1 : 2 and 1 : 4 Au : Pd) for benzyl alcohol oxidation increased ∼4‐fold after calcination. Upon reduction with H2, surface PdO motifs are reduced to Pd that did not dissolve back into the AuPd alloy core, maintaining the metallic Pd shell. The catalytic activity decreased. Therefore, restructuring alloyed AuPd nanoparticles into core‐shell like structures with PdO in the shell is beneficial to the catalytic activity, but reduction of PdO layer was detrimental. These results provide new insights on the optimization of AuPd catalysts, considering not only the Au/Pd molar ratio, but also the importance of PdO, which was not anticipated in the previous literature.