High Performance Pd,PdNi, PdSn and PdSnNi Nanocatalysts Supported on Carbon Nanotubes for Electrooxidation of C2C4 Alcohols

Nanocatalysts Pd, Pd₈Ni₂, Pd₈Sn₂ and Pd₈Sn₁Ni₁ supported on multi‐walled carbon nanotubes (MWCNTs) were successively synthesized by the chemical reduction method in the glycol‐water mixture solvent. Transmission electron microscopy results show that the prepared Pd, Pd₈Ni₂, Pd₈Sn₂ and Pd₈Sn₁Ni₁ nanoparticles are uniformly dispersed on the surface of MWCNTs. The average particle sizes of the nanocatalysts are 3.5–3.8 nm. Electroactivity of the prepared catalysts towards oxidation of ethanol, 1‐propanol, 2‐propanol, n‐butanol, iso‐butanol and sec‐butanol (C2? C4 alcohols) in alkaline medium was studied by cyclic voltammetry and chronoamperometry. The current density obtained for the electrooxidation of C2? C4 alcohols depends on the catalysts and the various structures of the alcohols. Addition of Sn or/and Ni to Pd nanoparticles enhances the electroactivity of the Pd/MWCNT catalyst. Furthermore, the ternary Pd₈Sn₁Ni₁/MWCNT catalyst presents the highest electroactivity for the oxidation of C2? C4 alcohols among the prepared catalysts. Electrocatalytic activity order among propanol isomers and butanol isomers is as follows respectively: 1‐propanol > 2‐propanol, and n‐butanol > iso‐butanol > sec‐butanol > tert‐butanol. This is consistent with the Mulliken charge value of the carbon atom bonded with hydroxyl group in the corresponding alcohol molecule.     

Preparation and characterization of H3−2(x+y)MnxCoyPMo12O40 heteropolysalts. Application to adipic acid green synthesis from cyclohexanone oxidation with hydrogen peroxide

H_3−2(x+y)Mn_xCo_yPMo₁₂O₄₀ heteropolysalts (x + y ≤ 3/2 and x, y: 0–1.5) were prepared by a cationic exchange method based on barium sulfate precipitation. Structural and textural properties of salts were examined by several physicochemical techniques such as infrared, scanning electron microscopy-energy dispersive X-ray, and ³¹P nuclear magnetic resonance spectroscopies, X-ray diffraction diffraction, and thermogravimetric analysis, and their catalytic properties were evaluated in the cyclohexanone oxidation using hydrogen peroxide (30%). The reaction products, adipic, glutaric, succinic, hexanoic, 6-hydroxyhexanoic, 7,7-dimethoxy, and heptanoic acids and 1,1-dimethoxy octane were identified by gas chromatography–mass spectrometry analysis. Only adipic, glutaric, and succinic acids were quantified by chromatography (high-performance liquid chromatography), the other products were noted X. Adipic acid (AA) is the major product for all systems. The effects of molar ratios of catalyst/reactant and cyclohexanol/cyclohexanone, heteropolysalt composition, and reaction duration on AA yield were investigated. The stability of the catalytic system was also examined. H_3−2(x+y)Mn_xCo_yPMo₁₂O₄₀ catalysts were found to be efficient for the cyclohexanone oxidation with conversions >95%. Among them, H₁Mn_0.25Co_0.75 exhibits the highest AA yield (75%).     

Polyaniline‐Modified Silver and Binary Silver‐Cobalt Catalysts for Oxygen Reduction Reaction

Novel dendrite‐like silver particles were electrodeposited on Ti substrates from a supporting electrolyte‐free 30 mmol L^?1 Ag(NH₃)₂⁺ solution, to synthesize the den‐Ag/Ti electrode. Binary Ag_xCo_y/Ti electrodes with different Ag:Co atomic ratios were further obtained by electrodeposition of Co particles on the den‐Ag/Ti electrode. Polyaniline (PANI) modified den‐Ag/Ti and Ag_xCo_y/Ti electrodes, PANI(n)‐den‐Ag/Ti and PANI(n)‐Ag_xCo_y/Ti, were also obtained by cyclic voltammetry at different numbers of cycles (n) in acidic and alkaline solutions containing aniline, respectively. All these electrodes exhibit high electroactivity for oxygen reduction reaction (ORR) in alkaline solution and their electroactivities follow the order: PANI(15)‐Ag₃₁Co₆₉/Ti>Ag₃₁Co₆₉/Ti>PANI(20)‐den‐Ag/Ti>den‐Ag/Ti. Among them, PANI(15)‐Ag₃₁Co₆₉/Ti displays the highest electrocatalytic activity for ORR with a much positive onset potential of 0 V (vs. Ag/AgCl) and a high ORR current density of 1.2 mA cm^?2 at ?0.12 V (vs. Ag/AgCl). The electrocatalysts are electrochemically insensitive to methanol and ethanol oxidation, and, as cathode electrocatalysts of direct alcohol fuel cells, can resist poisoning by the possible alcohol crossover from the anode.     

Electronic Modulation of Palladium in Metal Phosphide Nanoparticles for Chemoselective Reduction of Halogenated Nitrobenzenes

Tuning the electronic property of a transition metal plays an important role in the selective catalysis. Herein, the control synthesis of (Pd_xNi_y)‐P nanoparticles is reported. The binding energy of Pd3d_5/2 as a function of x/y ratio is well tunable from 335.3 to 335.9 eV. The composition‐induced electronic modulation was correlated with the selective catalysis of (Pd_xNi_y)‐P in the reduction of halogenated nitrobenzenes. The electro‐deficiency of Pd helped to improve the selectivity. The amorphous (Pd₃₈Ni₂₆)P₃₆/C performed an exceptional selectivity in comparison with other related (Pd‐Ni)‐P/C, Pd₃₈Ni₂₆/C, and Pd/C. Various halogenated nitrobenzenes (chlorides, bromides, and iodide) were tolerant and the corresponding halogenated anilines were obtained in high yields. This work provides some clues for the rational design of bimetallic phosphides with covalent interactions to boost the catalysis.     

Three Series of Sulfo‐Functionalized Mixed‐Linker CAU‐10 Analogues: Sorption Properties,Proton Conductivity,and Catalytic Activity

Ten mixed‐linker metal–organic frameworks [Al(OH)(m‐BDC‐X)_1?y(m‐BDC‐SO₃H)_y] (H₂BDC=1,3‐benzenedicarboxylic acid; X=H, NO₂, OH) exhibiting the CAU‐10‐type structure were synthesized. The compounds can be grouped into three series according to the combination of ligands employed. The three series of compounds were obtained by employing different ratios of m‐H₂BDC‐X and m‐H₂BDC‐SO₃Li. The resulting compounds, which are denoted CAU‐10‐H/Sx, ‐N/Sx and ‐O/Sx, show exceptionally high thermal stability for sulfonated materials of up to 350 °C. Detailed characterization with special focus on polarity and acidity was performed, and the impact of the additional SO₃H groups is clearly demonstrated by changes in the sorption affinities/capacities towards several gases and water vapor. In addition, selected samples were evaluated for proton conductivity and as catalysts for the gas‐phase dehydration of ethanol to ethylene. While only very low proton conductivities were observed, a pronounced increase in catalytic activity was achieved. Although reactions were performed at temperatures of 250 and 300 °C for more than 40 h, no desulfonation and no loss of crystallinity were observed, and stable ethanol conversion resulted. This demonstrates the high stability of this material.     

Tb3Pd2, Er3Pd2 and Er6Co5–x: structural variations and bonding in rare‐earth‐richer binary intermetallics

The three binary Tb/Er‐rich transition metal compounds Tb₃Pd₂ (triterbium dipalladium), Er₃Pd₂ (trierbium dipalladium) and Er₆Co_5–x (hexaerbium pentacobalt) crystallize in the space groups Pbam (Pearson symbol oP20), P4/mbm (tP10) and P6₃/m (hP22), respectively. Single crystals of Tb₃Pd₂ and Er₆Co_5–x suitable for X‐ray structure analysis were obtained using rare‐earth halides as a flux. Tb₃Pd₂ adopts its own structure type, which can be described as a superstructural derivative of the U₃Si₂ type, which is the type adopted by Er₃Pd₂. Compound Er₆Co_5–x belongs to the Ce₆Co_2–xSi₃ family. All three compounds feature fused tricapped {TR₆} (R = rare‐earth metal and T = transition metal) trigonal prismatic heterometallic clusters. R₃Pd₂ is reported to crystallize in the U₃Si₂ type; however, our more detailed structure analysis reveals that deviations occur with heavier R elements. Similarly, Er₆Co_5–x was assumed to be stoichiometric Er₄Co₃ = Er₆Co_4.5. Our studies reveal that it has a single defective transition‐metal site leading to the composition Er₆Co_4.72(2). LMTO (linear muffin‐tin orbital)‐based electronic structure calculations suggest the strong domination of heteroatomic bonding in all three structures.     

Facile Synthesis of Pd‐Ni Nanoparticles on Reduced Graphene Oxide under Microwave Irradiation for Formic Acid Oxidation

Pd and Pd_x Ni nanoparticles have been supported on reduced graphene oxide (Pd/rGO and Pd_x Ni/rGO ) by using the microwave‐assisted heating method in glycol. The morphology, composition and electrochemical performance have been characterized by TEM , XRD , XPS and electrochemical methods. The XRD and XPS results show that there are no PdNi alloy particles formed in Pd_x Ni/rGO and the composites exist mostly in the form of Pd⁰ and NiOOH species. The electrochemical results reveal that Pd_x Ni/rGO synthesized from the feeding source of Pd and Ni with an atomic ratio of 4∶1 exhibits higher activity, better stability and smaller electron transfer resistance toward formic acid electro‐oxidation compared with commercial Pd/C, Pd/rGO and other Pd_x Ni/rGO samples. The excellent electrocatalytic performance indicates that the addition of appropriate amount of Ni can greatly enhance the activity and stability of Pd catalysts for formic acid oxidation.     

A Flame‐Reaction Method for the Large‐Scale Synthesis of High‐Performance SmxCoy Nanomagnets

We report a flame‐reaction method to synthesize high‐performance Sm_xCo_y (x=1, y=5; x=2, y=17) particles on a multigram scale. This flame reaction allows the controlled decomposition of Sm(NO₃)₃ and Co(NO₃)₂ to 320 nm SmCo‐O (SmCoO₃ + Co₃O₄) particles. A 5.8 g sample of SmCo_3.8‐O particles was coated with CaO and then reduced at 900 °C by Ca to give 4.2 g of 260 nm SmCo₅ particles. The SmCo₅ particles are strongly ferromagnetic and the aligned particles in epoxy resin exhibit a large room‐temperature coercivity (H_c) of 41.8 kOe and giant (BH)_max (maximum magnetic energy product) of 19.6 MGOe, the highest value ever reported for SmCo₅ made by chemical methods. This synthesis can be extended to synthesize Sm₂Co₁₇ particles, providing a general approach to scaling up the synthesis of high‐performance Sm_xCo_y nanomagnets for permanent magnet applications.     

A Molecular Approach to Self‐Supported Cobalt‐Substituted ZnO Materials as Remarkably Stable Electrocatalysts for Water Oxidation

In regard to earth‐abundant cobalt water oxidation catalysts, very recent findings show the reorganization of the materials to amorphous active phases under catalytic conditions. To further understand this concept, a unique cobalt‐substituted crystalline zinc oxide (Co:ZnO) precatalyst has been synthesized by low‐temperature solvolysis of molecular heterobimetallic Co_4?xZn_xO₄ (x=1–3) precursors in benzylamine. Its electrophoretic deposition onto fluorinated tin oxide electrodes leads after oxidative conditioning to an amorphous self‐supported water‐oxidation electrocatalyst, which was observed by HR‐TEM on FIB lamellas of the EPD layers. The Co‐rich hydroxide‐oxidic electrocatalyst performs at very low overpotentials (512 mV at pH 7; 330 mV at pH 12), while chronoamperometry shows a stable catalytic current over several hours.     

Synthesis and properties of PdSn/Al2O3 and PdSn/SiO2 prepared by solvated metal atom dispersed method

A series of solvated metal atom dispersion (SMAD) catalysts: Pd/SiO₂, Pd/Al₂O₃, Sn/SiO₂, Sn/Al₂O₃, Pd_xSn_y/SiO₂ and Pd_xSn_y/Al₂O₃. It was prepared by simultaneous evaporation of Pd and Sn. The metals were co-deposited at 77 K using acetone, 2-propanol and THF to produce colloids “in situ” all the supported catalyst were characterized by chemisorption, transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and TPR. This series of catalyst were tested for crotonaldehyde hydrogenation in gas phase to obtain crotyl alcohol.     

Activating CoOOH Porous Nanosheet Arrays by Partial Iron Substitution for Efficient Oxygen Evolution Reaction

Iron‐substituted CoOOH porous nanosheet arrays grown on carbon fiber cloth (denoted as Fe_xCo_1?xOOH PNSAs/CFC, 0≤x≤0.33) with 3D hierarchical structures are synthesized by in situ anodic oxidation of α‐Co(OH)₂ NSAs/CFC in solution of 0.01 m (NH₄)₂Fe(SO₄)₂. X‐ray absorption fine spectra (XAFS) demonstrate that CoO₆ octahedral structure in CoOOH can be partially substituted by FeO₆ octahedrons during the transformation from α‐Co(OH)₂ to Fe_xCo_1?xOOH, and this is confirmed for the first time in this study. The content of Fe in Fe_xCo_1?xOOH, no more than 1/3 of Co, can be controlled by adjusting the in situ anodic oxidation time. Fe_0.33Co_0.67OOH PNSAs/CFC shows superior OER electrocatalytic performance, with a low overpotential of 266 mV at 10 mA cm^?2, small Tafel slope of 30 mV dec^?1, and high durability.     

Catalytic partial oxidation of methanol over Au–Pd bimetallic catalysts: a comparative study of SBA-16, SBA-16-CeO<Subscript>2</Subscript>, and CeO<Subscript>2</Subscript> as supports

Au–Pd catalysts supported on SBA-16, SBA-16-CeO₂, and CeO₂ had been studied for partial oxidation of methanol to produce H₂. The physicochemical characteristics of the catalysts prepared by deposition–precipitation using urea hydrolysis were examined by inductively coupled plasma atomic emission spectroscopy (ICP-AES), Brunauer-Emmett-Teller (BET), X-ray powder diffraction (XRD), Temperature-programmed reduction (TPR), and H₂ temperature-programmed desorption (H₂-TPD) analyses. The results show that Au_xPd_y alloys are observed in Au–Pd/SBA-16 and Au–Pd/SBA-16-CeO₂ catalysts. The catalytic results demonstrate that both Au–Pd/SBA-16 and Au–Pd/SBA-16-CeO₂ catalysts exhibit higher activity and lower CO selectivity than the Au–Pd/CeO₂ catalyst. This could be ascribed to the formation of Au_xPd_y alloys. The comparison of the Au–Pd/SBA-16 and Au–Pd/SBA-16-CeO₂ catalysts reveals that the Au–Pd/SBA-16-CeO₂ shows the lower CO selectivity, probably due to the presence of CeO₂.     

Oxygen species and their reactivity in the mechanochemically prepared substituted perovskites La1 ? xSrxCoO3 ? y (x = 0–1)

The oxygen species and their reactivity in the mechanochemically prepared substituted perovskites La_{1 − x} Sr _x CoO_{3 − y} were studied using temperature-programmed reduction (TPR) of the samples with hydrogen. The experimental data were compared with data on the catalytic activity of the series of La_{1 − x} Sr _x CoO_{3 − y} catalysts in the oxidation of CO, as well as with the real structures and surface compositions of the samples, which were studied in detail previously. As the strontium content was increased, the degree of reduction of the samples increased in the course of TPR and the TPR peaks shifted to the region of lower temperatures, except for the last sample containing no lanthanum (x = 1). An increase in the calcination temperature and time resulted in a decrease in TPR peak intensities and in a shift of the peaks to the region of higher temperatures. A reaction scheme was proposed for the reduction. In accordance with this reaction scheme, Co⁴⁺ in substituted cobaltites was reduced to Co⁰ at temperatures lower than 400°C. In the temperature region of 400–500°C, the Co³⁺ → Co²⁺ bulk reduction, as well as the deep reduction processes Co³⁺ → Co⁰ and Co⁴⁺ → Co⁰, occurred; substitution facilitated the above processes. At temperatures higher than 500°C, Co²⁺ → Co⁰ bulk reduction occurred. The observed reduction of the mechanochemically prepared samples depended on their microstructure, which was described previously. It was found that the activity of the samples in the oxidation of CO depends on the amount of the most weakly bound reactive surface oxygen species, which were removed in TPR with hydrogen to 150°C. No correlation between the amount of strongly bound (lattice) oxygen removed upon TPR and the activity of La_{1 − x} Sr _x CoO_{3 − y} samples in the oxidation of CO was found. Original Russian Text ? I.S. Yakovleva, L.A. Isupova, V.A. Rogov, 2009, published in Kinetika i Kataliz, 2009, Vol. 50, No. 2, pp. 290–299.     

Convenient and Mild Epoxidation of Alkenes Using Heterogeneous Cobalt Oxide Catalysts

A general epoxidation of aromatic and aliphatic olefins has been developed under mild conditions using heterogeneous Co_xO_y–N/C (x=1,3; y=1,4) catalysts and tert‐butyl hydroperoxide as the terminal oxidant. Various stilbenes and aliphatic alkenes, including renewable olefins, and vitamin and cholesterol derivatives, were successfully transformed into the corresponding epoxides with high selectivity and often good yields. The cobalt oxide catalyst can be recycled up to five times without significant loss of activity or change in structure. Characterization of the catalyst by XRD, TEM, XPS, and EPR analysis revealed the formation of cobalt oxide nanoparticles with varying size (Co₃O₄ with some CoO) and very few large particles with a metallic Co core and an oxidic shell. During the pyrolysis process the nitrogen ligand forms graphene‐type layers, in which selected carbon atoms are substituted by nitrogen.     

Catalytic oxidation of methane at low temperature over Pd-containing perovskite type oxides

Two types of catalysts with the same palladium loading, palladium-substituted perovskite La_0.95Ce_0.05Co_0.95Pd_0.05O₃ and perovskite-supported palladium catalyst Pd/La_0.95Ce_0.05CoO₃ were prepared by the combustion and impregnation method, respectively. The catalyst structure was characterized by X-ray diffraction (XRD), BET measurements, temperature-programmed reduction (TPR) and the methane oxidation activity of the catalysts were investigated in detail. It was found that the activity performance of Pd/La_0.95Ce_0.05CoO₃ was higher than that of La_0.95Ce_0.05Co_0.95Pd_0.05O₃, and this was owing to the ease of reduction of palladium in the former.     

Effects of Ethanol Impregnation on the Catalytic Properties of Silica-Supported Cobalt Catalysts

Silca-supported Co₃O₄ (6 wt% as Co) catalysts were prepared by pore volume impregnation of ethanol or aqueous cobalt nitrate solutions, and calcined in vacuo to 300 °C. The catalytic performances of these catalysts for oxidation and hydrogenation of CO were examined. All Co₃O₄/SiO₂ catalysts were found to be very active in catalyzing oxidation of CO to CO₂ as compared to a commercial 1 wt% Pt/Al₂O₃. The ethanol-prepared catalysts exhibited higher activity than those of the aqua-prepared catalysts. Pre-calcination of the ethanol-prepared catalysts in oxygen at 600 °C resulted in a dramatic decrease in the activity. Temperature programmed oxidation indicated the presence of carbon deposits on the surface of used catalysts. Infrared spectra showed the continuous generation of CO₂ when these catalysts were exposed to CO. These indicate the primary role of CO disproportionation in catalytic oxidation of CO on Co₃O₄ at low temperature and explain the sharp decrease in activity in the initial period. After reduction at 400 °C, the ethanol-prepared catalysts were also found to be more active in catalyzing hydrogenation of CO, and produced less methane and olefin (C2-C4) fraction. Higher turnover frequencies were observed after high temperature reduction (600 °C) as well, at which ethoxyl groups were removed from silica surface. In both reactions, the enhanced activity for the ethanol-prepared catalysts can not be fully accounted for by the increase in the dispersion of Co₃O₄ or CO metal. This suggests that the surface structures of Co₃O₄ or CO were further modified by the carbonaceous species derived from ethanol.     

离子液体中水热合成Pt-Pd/MWCNTs和Pd/MWCNTs催化剂

采用水热合成法, 以离子液体1-乙基-3-甲基咪唑四氟硼酸盐(C₆H₁₁BF₄N₂, EMIBF₄)为溶剂制备了Pt-Pd/MWCNTs(Multi-walled carbon nanotubes)和Pd/MWCNTs催化剂. X射线衍射(XRD)和X射线能量散射谱(EDS)测试证明了Pt-Pd合金和Pd纳米颗粒在MWCNTs的表面生成. 透射电子显微镜(TEM)照片不仅证明了在MWCNTs表面Pt-Pd, Pd纳米颗粒的生成, 而且还表明样品颗粒的平均粒径约为4 nm. 循环伏安(CV)和交流阻抗(EIS)测试表明, 在碱性环境下, 乙醇在Pt-Pd/MWCNTs和Pd/MWCNTs修饰的玻碳(GC)电极上均能发生氧化反应, 与Pd/MWCNTs修饰的电极相比, 在Pt-Pd/MWCNTs上乙醇的起峰电位负移了大约200 mV, 且具有更高的氧化峰电流值.     

Porous CuxCoyS Supraparticles for In Vivo Telomerase Imaging and Reactive Oxygen Species Generation

In this study, we successfully synthesized Cu_xCo_yS supraparticles (SPs) on the nanoscale featuring multiple pores inside and strong absorption from 400 to 900 nm. Porous Cu_xCo_yS SPs produced the highest reactive oxygen species (ROS) yield (1.39) when illuminated with near‐infrared (NIR) light. Furthermore, we demonstrated that Cu_xCo_yS SPs could be used to identify cancer cells through intracellular telomerase‐responsive fluorescence (FL) imaging in living cells. Because the Cu_xCo_yS SPs were associated with telomerase‐responsive bioimaging and high ROS production, they can be efficiently used in the diagnosis and therapy of tumors with high selectivity and excellent therapeutic effects in vivo. This study provides a new vision for the creation of multifunctional SPs, which can be used as cellular sensors and control tools for pathologies across a broad range of biological systems.     

Monolithically Integrated Spinel MxCo3−xO4 (M=Co,Ni, Zn) Nanoarray Catalysts: Scalable Synthesis and Cation Manipulation for Tunable Low‐Temperature CH4 and CO Oxidation

A series of large scale M_xCo_3−xO₄ (M=Co, Ni, Zn) nanoarray catalysts have been cost‐effectively integrated onto large commercial cordierite monolithic substrates to greatly enhance the catalyst utilization efficiency. The monolithically integrated spinel nanoarrays exhibit tunable catalytic performance (as revealed by spectroscopy characterization and parallel first‐principles calculations) toward low‐temperature CO and CH₄ oxidation by selective cation occupancy and concentration, which lead to controlled adsorption–desorption behavior and surface defect population. This provides a feasible approach for scalable fabrication and rational manipulation of metal oxide nanoarray catalysts applicable at low temperatures for various catalytic reactions.     

Structural and Electronic Effects of Carbon‐Supported PtxPd1−x Nanoparticles on the Electrocatalytic Activity of the Oxygen‐Reduction Reaction and on Methanol Tolerance

We report a systematic investigation on the structural and electronic effects of carbon‐supported Pt_xPd_1?x bimetallic nanoparticles on the oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) in acid electrolyte. Pt_xPd_1?x/C nanocatalysts with various Pt/Pd atomic ratios (x=0.25, 0.5, and 0.75) were synthesized by using a borohydride‐reduction method. Rotating‐disk electrode measurements revealed that the Pt₃Pd₁/C nanocatalyst has a synergistic effect on the ORR, showing 50 % enhancement, and an antagonistic effect on the MOR, showing 90 % reduction, relative to JM 20 Pt/C on a mass basis. The extent of alloying and Pt d‐band vacancies of the Pt_xPd_1?x/C nanocatalysts were explored by extended X‐ray absorption fine‐structure spectroscopy (EXAFS) and X‐ray absorption near‐edge structure spectroscopy (XANES). The structure–activity relationship indicates that ORR activity and methanol tolerance of the nanocatalysts strongly depend on their extent of alloying and d‐band vacancies. The optimal composition for enhanced ORR activity is Pt₃Pd₁/C, with high extent of alloying and low Pt d‐band vacancies, owing to favorable O? O scission and inhibited formation of oxygenated intermediates. MOR activity also shows structure dependence. For example, Pt₁Pd₃/C with Pt_rich?corePd_rich?shell structure possesses lower MOR activity than the Pt₃Pd₁/C nanocatalyst with random alloy structure. Herein, extent of alloying and d‐band vacancies reveal new insights into the synergistic and antagonistic effects of the Pt_xPd_1?x/C nanocatalysts on surface reactivity.