mA mgPd Research Articles

Construction of Multiphase Concave Tetrahedral PdInMo Nanocatalyst for Enhanced Alcohol Oxidation

AbstractHeterogeneous palladium‐based catalysts show excellent catalytic properties for electrocatalytic oxidation of alcohols, but the construction of such heterogeneous catalysts is a challenge. Here, a multiphase tetrahedral PdInMo nanocatalyst is prepared by a one‐pot reaction method. And the multiphase tetrahedral PdInMo nanocatalyst consists of a face‐centered cubic structure and an intermetallic structure. Due to the oxygen affinity of indium and molybdenum atoms, the interface defects of internal multiphase structure, and intermetallic structure, the multiphase concave tetrahedral PdInMo nanocatalyst shows enhanced catalytic efficiency in the electrocatalytic oxidation reaction of methanol and ethanol. Compared with commercial Pd/C catalysts, PdIn0.117Mo0.037 nanocatalyst has the best mass activity and specific activity. In electrocatalysis of methanol oxidation, the mass activity (2205.57 mA mgPd−1) and specific activity (6.67 mA cm−2) are 4.81 and 3.40 times than that of a commercial Pd/C nanocatalyst (458.5 mA mgPd−1, 1.96 mA cm−2), respectively. In the electrocatalysis of ethanol oxidation, the mass activity (2668.49 mA mgPd−1) and specific activity (8.11 mA cm−2) are 4.06 and 3.14 times than that of the commercial Pd/C nanocatalyst (655.83 mA mgPd−1, 2.58 mA cm−2), respectively. This study provides a reference for the design of highly efficient palladium catalysts for alcohol oxidation.

Enhancing the Catalytic Activity of Pd Nanocatalysts for Anion Exchange Membrane Direct Ethanol Fuel Cells by Functionalizing Vulcan XC-72 with Cu Organometallic Compounds.

The most widely used support in low-temperature fuel cell applications is the commercially available Vulcan XC-72. Herein, we report its functionalization with the home-obtained mesityl copper (Cu-mes) and Cu coordinate (Cu(dmpz)L2) organometallic compounds. Pd nanoparticles are anchored on the supports obtaining Pd/CCu-mes, Pd/CCu(dmpz)L2, and Pd/C (on nonfunctionalized support). The polarization curves of the ethanol oxidation reaction (EOR) show that Pd/CCu-mes and Pd/CCu(dmpz)L2 promote the reaction at a more negative onset potential, i.e., E onset = 0.38 V/reversible hydrogen electrode (RHE), compared to 0.41 V/RHE of Pd/C. The mass current density (j m) delivered by Pd/CCu-mes is considerably higher (1231.3 mA mgPd -1), followed by Pd/CCu(dmpz)L2 (1001.8 mA mgPd -1), and Pd/C (808.3 mA mgPd -1). The enhanced performance of Pd/CCu-mes and Pd/CCu(dmpz)L2 for the EOR (and tolerance to CO poisoning) is attributed to a shift of their d-band center toward more negative values, compared to Pd/C, because of the formation of PdCu alloyed phases arising from the functionalization. In addition, laboratory-scale tests of the anion exchange membrane-direct ethanol fuel cell assembled with Pd/CCu-mes show the highest open circuit voltage (OCV = 0.60 V) and cell power density (P cell = 0.14 mW cm-2). As a result of its high catalytic activity, Pd/CCu-mes can find application as an anode nanocatalyst in AEM-DEFCs.

High-efficient electrooxidation of ethylene glycol and ethanol on PdSn alloy loaded by versatile poly(3,4-ethylenedioxythiophene)

Developing a novel catalyst with lower noble-metal loading and higher catalytic efficiency is significant for promoting the widespread application of direct alcohol fuel cells (DAFCs). In this work, poly(3,4-ethylenedioxythiophene) (PEDOT) supported the PdSn alloy (PdSn/PEDOT) were simply synthesized and their electrocatalytic performance toward the oxidation of ethylene glycol and ethanol (EGOR and EOR) were investigated in alkaline media, respectively. In comparison with other control catalysts, the optimized Pd4Sn6/PEDOT catalyst exhibits the highest mass activity (7125/4166 mA mgPd−1) and specific activity (26/15 mA cm−2) towards EGOR/EOR. The mass activity of Pd4Sn6/PEDOT for EGOR and EOR are 11.9 and 10.9 times higher than commercial Pd/C, respectively. Moreover, chronoamperometry (CA) and successive cyclic voltammetry (CV) tests show that the CO resistance ability and durability of the Pd4Sn6/PEDOT catalyst were superior to Pd4Sn6, Pd/PEDOT and commercial Pd/C catalysts, which can be attributed to the d-band center of Pd can be effectively downshifted and the interface strain effect between electrons caused by the conjugated structure between PEDOT groups. This work provides an effective strategy for the development of highly efficient anode catalysts of DAFCs.

Facile synthesis of highly active PdAu alloy nanochains for alcohol oxidation electrocatalysis

An efficacious strategy to enhance the activity and stability of electrocatalysts for alcohol oxidation reactions is the formation of alloys of palladium with oxygenophilic metals. In this study, Palladium nano chains with an average diameter of approximately 4.4 nm were synthesized via a one-step hydrothermal approach, employing creatine as the structural guide. The one-dimensional structure yielded a huge electrochemically active area (84.5 m2 g−1) and good electrical conductivity. the mass activity of Pd87Au13 NCs for alkaline ethanol oxidation reaction was 4050 mA mgPd+Au−1, which is 7.32 times higher thancommercial Pd/C, and also maintains a high residual current density after 20000 s stability test. In addition, the excellent performance of the material was demonstrated during the oxidation of ethylene glycol and glycerol. The improved catalytic performance is owed to the interconnected chain shape providing fast electron transport channels, and the Au doping not only optimizes the electronic structure of Pd but also has a bifunctional effect, which effectively removes the carbon-containing intermediates generated by Pd during alcohol oxidation, thus improving its resistance to poisoning and stability.

Synergistic Effect of Trimetallic PdCuIn Nanoparticles in Ethanol and Formate Oxidation Reaction for Remarkable Catalytic Performance

Direct liquid fuel cells (DLFC) are regarded as attractive energy devices with their advantages of sustainability and eco‐friendly operation. Pd‐based materials have been recognized as ideal catalysts for anodic oxidation of DLFC. Although reasonably regulating the structure of Pd‐based catalysts to achieve remarkable catalytic performance, it is not clear about the combined effects of d‐band center and charge transfer, which are the crucial impactors for catalytic activity. Herein, a facile method to synthesize trimetallic PdCuIn nanoparticles (PdCuIn NPs) for ethanol and formate oxidation reactions (EOR and FOR, respectively) is reported. PdCuIn NPs exhibits bifunctional catalytic activities for both EOR and FOR, with mass activities of 16 000 and 15 500 mA mgPd−1, respectively, which are much better than those of commercial Pd/C catalysts. Comparing to the bimetallic nanoparticles (PdCu or PdIn NPs), additional Cu or In enhances the electron transfer and achieves a suitable d‐band center, resulting in excellent performance. This work synthesizes a highly active catalyst for both EOR and FOR, but also provides facile strategy of balancing the d‐band center and charge transfer for high catalytic performance.

Controlling the Reactivity and Interactions between Hydrogen and Palladium Nanoparticles via Management of the Particle Diameter

AbstractTailoring the interactions between hydrogen and palladium is crucial for numerous industrial and research applications. The fine control of Pd nanoparticles (NPs) diameter is promising to address this problem when other means, i. e. temperature, pressure, or cell voltage, are set by the ongoing process. We investigate the electrochemical behaviour of Pd NPs in the presence of hydrogen over a large range of particle diameters, between 3.8–21.5 nm. The study is carried out in both a three‐electrode setup and a proton pump. A linear relationship between the H/Pd ratios and the NPs diameter is evidenced. The increase in particle size is accompanied by an extension of the loading duration to reach a stable hydride. Beyond H absorption, the HER and HOR kinetics are examined as a function of the particle diameter. The smaller the particle the higher the catalytic activity, with exchange currents ranging between approx. 1.7–9.8 mA mgPd−1.

Nanoflower core-shell Cu@Pd catalysts for glycol oxidation reaction with an enhanced performance

Direct alcohol fuel cells' performance is significantly affected by the phase and composition of the catalyst, thereby the development of high-performance alcohol oxidation catalysts is essential. In this study, PVA preparation was used for the first time to create PdCu core-shell nanoflowers with a high electrochemically active surface area and a potent synergistic effect. Notably, the presence of PVA causes Pd and Cu nanoparticles with different reduction rates to form a core-shell structure, and the Pd nanoparticles continue to migrate regularly under the action of PVA, forming a flower-like morphology with a high degree of branching. Cu@Pd22.3 catalyst exhibited 13 times higher catalytic performance (4353.04 mA mgPd−1) than Pd/C (334.09 mA mgPd−1) in ethylene glycol oxidation reaction. The Cu@Pd22.3 catalyst also exhibits higher stability than commercial Pd/C in stability tests lasting up to 20,000 s. This core-shell combination and highly branched structural design result in more active sites for fast ion adsorption/desorption,offering an original method to improving the activity and endurance of polyol oxidation.

CuFe2O4 spinel synergize with Pd as a robust electrocatalyst for formate oxidation reaction

As an energy conversion device, direct formate fuel cell (DFFC) has attracted much attention due totheir security, affordability as well as high energy conversion efficiency. However, the whole performance of the DFFC is unsatisfactory because of the repaid activity loss induced by Hads-poisoning of anode Pd catalysts during the formate oxidation reaction (FOR). Herein, we induced a CuFe2O4 complex into Pd to enhance the activity and release the Hads-poisoning to prolong the durability. The results reflect that the *OH generation capacity of CuFe2O4 played an important role in the Hads-stripping (Pd-Hads + CuFe2O4-OHads → Pd + CuFe2O4 + H2O). After optimized PCFO-3 (Pd/CuFe2O4) not only show a super FOR activity of 4427 mA mgPd−1 mass activity and 243 mA cm−2 specific activity, but also show a novel cycle durability of 10,000 times CV cycles and 12 h long-term i-t operation with a termination activity of 26.95 mA mgPd−1. More interestingly, this PCFO-3 shows a self-adapting process which induced an activity enhancement of 27.6% due to the synergistic effect of CuFe2O4 and Pd. We believe this work paves a new avenue for matching counterparts to enhance the FOR activity and durability of Pd electro-catalysts cooperatively.

Palladium nanoparticles anchored on MXene-based N-doped porous carbon nanosheets as an advanced electrocatalyst for ethanol oxidation

Pd-based electrocatalysts with advanced activity and durability can greatly accelerate the commercial process of direct ethanol fuel cells (DEFCs). However, Pd nanoparticles (NPs) are easily aggregated and deactivated during the ethanol oxidation reaction (EOR), which will restrict their electrocatalytic efficiency during the long-term running. To solve these problems, we develop new sandwich-like MXene-based N-doped porous carbon (NPCM) through carbonizing and acid etching of ZIF/MXene composite nanosheets. The derived NPCM nanosheets possess a highly ordered nano-porous and N-doped structure, which can be used as competitive catalyst supports to highly disperse Pd NPs and effectively avoid the aggregation and deactivation of Pd NPs. Meanwhile, the as-synthesized Pd/NPCM can offer more activity sites and more space for electrocatalysis reaction, leading to excellent CO tolerance. Thanks to the combination of MXene and ZIF, the designed Pd/NPCM electrocatalyst can offer connected channels for the fast diffusion of reactants and products. Impressively, the Pd/NPCM electrocatalyst exhibits a mass activity of 2237 mA·mgPd−1, which is 1.90 and 6.37 folds that of Pd/ZIF (1179 mA mgPd−1) and Pd/C (351 mA mgPd−1) electrocatalyst, respectively. This work not only explores a novel strategy for preparing advanced electrocatalyst support materials but also opens up their wide applications in DEFCs.

Sphere-like PdNi Alloy: Unveiling the Twin Functional Properties toward Oxygen Reduction and Temperature-Dependent Methanol Oxidation for Alkaline Direct Methanol Fuel Cells

The development of high-performance bifunctional palladium-based (Pd) alloys for the oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) is a great challenge in direct methanol fuel cells. The incorporation of an oxophilic atom into the Pd atom is an effective strategy to enhance the electrocatalytic activity of the catalysts. Herein a sphere-like PdNi alloy (sPdNiA) was developed via a simple hydrazine-assisted reduction method to overcome the kinetic drawbacks of palladium and delivers superior ORR/MOR performance. The successful alloy formation, the induced strain effect in the electronic structure, and structural characteristics of the sPdNiA were confirmed through XRD, XPS, and HR-TEM studies. As a result, for ORR, the sPdNiA exhibits a positive halfwave potential (E1/2) of ∼0.854 V (vs RHE) compared to the pure Pd (0.833 V vs RHE) nanoparticles. For MOR, the sPdNiA presents the low onset potential and high mass activity of 518 mA mgPd–1 in 1.0 M KOH electrolyte. Furthermore, the temperature-dependent MOR and 3D Bode plot investigations reveal a five-fold higher mass activity at elevated temperature (60 °C) with a lower activation energy (Ea). For the first time, the direct methanol fuel cell is fabricated utilizing sPdNiA as a bifunctional electrode, exhibited a higher peak power density (Pmax) of 34 mW cm–2, whereas 22 mW cm–2 was obtained for Pd Np-based fuel cells. Incorporating oxophilic atom (Ni) not only improves the performance of Pd but significantly reduces the cost of the catalyst material by lowering the Pd content.

Controlled synthesis of Pd–Ag nanowire networks with high-density defects as highly efficient electrocatalysts for methanol oxidation reaction

Pd–Ag bimetallic catalysts containing different molar ratios of Pd/Ag (30/70, 50/50, and 70/30) were prepared using a facile visible-light-assisted liquid-phase method. The samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, high-resolution transmission electron microscopy, high-angle annular dark-field scanning transmission electron microscopy, selected-area electron diffraction, and inductively coupled plasma optical emission spectroscopy. Cyclic voltammetry and chronoamperometry measurements were used to evaluate their electrocatalytic properties toward the methanol oxidation reaction (MOR) in alkaline media. The alloyed Pd50Ag50 nanowire network with the optimized molar ratio, which had abundant defects (grain boundaries, lattice dislocations, lattice expansion, and distortion), provided more active sites for the MOR under alkaline conditions. The onset potential of the MOR on the Pd50Ag50-loaded glassy carbon electrode (GCE) was more negative than those on the Pd30Ag70, Pd70Ag30, and pure Pd electrodes. The Pd50Ag50 catalyst showed the best catalytic activity (2853 mA mgPd−1/6.85 mA cmPd−2) compared with those of the pure Pd catalyst (320 mA mgPd−1/2.68 mA cmPd−2) and other samples. This sample also exhibited a high tolerance (ib/if = 0.19) to the poisoning species and long stability (only lost 7.64 % after 500 cycles). The alloyed Pd50Ag50 network is a promising catalyst for the MOR. This work may be extended to construct advanced Pd–M (M = other metals) catalysts for fuel cell applications by surface defect engineering.

Tailoring the electronic structure of PdAgx alloy nanowires for high oxygen reduction reaction

Lowering the cost while maintaining the highly catalytic performance is greatly beneficial for the development of commercial fuel cells and metal-air batteries. Compared with platinum, palladium holds a stronger oxygen affinity and high abundance on earth, endowing it a promising alternative to platinum in anion-exchange membrane fuel cells. However, the sluggish oxygen reduction reaction of palladium still remains a great issue and requires the design of stable and efficient palladium-based electrocatalysts. Here, we report the solvothermal/hydrothermal reduction method to prepare a series of PdAgx nanowires. The prepared PdAgx NWs exhibit hollow structure, which greatly improves the utilization of Pd atoms, offering an outstanding ORR performance. Specifically, PdAg2 NWs exhibit an onset potential of 0.92 V and mass activity of 350.7 mA mgPd−1 at 0.7 V vs. RHE for ORR in 0.1 M KOH solution. This work provides a novel approach for the construction of hollow NWs and their subsequent applications in other electrocatalytic reactions.

Strain Engineering of Face-Centered Cubic Pd–Pb Nanosheets Boosts Electrocatalytic Ethanol Oxidation

Strain engineering of nanomaterials provides a promising avenue to tune the physicochemical properties of nanomaterials. Meanwhile, preparing low-dimension nanomaterials like nanosheets in a facile way remains challenging. Herein, we prepared a class of strained 2D palladium–lead nanosheets with face-centered cubic structures. Those nanosheets can expose a lot of active sites for ethanol oxidation reaction (EOR). The strain values of PdPb-CA are calculated to be 0.2, 1.5, and 2.0%, where the corresponding values increase as more lead atoms are doping, followed by decreased binding energies. This means that the strain effect would upshift the d-band center toward the Fermi level, with a consequence in stronger binding ability. Impressively, PdPb-CA-2 possesses 2431 mA mgPd–1 toward EOR, approximately 4.2 times higher than the commercial Pd/C counterpart. Interestingly, PdPb-CA exhibits a “volcano-type” behavior, where the maximum electrocatalytic activity can be obtained from the equilibrium condition of the adsorption energies of the active intermediate (OH*) and the blocking species (CO*). This work reveals a promising approach to constructing low-dimensional nanocatalysts with abundant active sites and controllable strain degrees as efficient fuel cell catalysts.

Monodispersed ultrathin twisty PdBi alloys nanowires assemblies with tensile strain enhance C2+ alcohols electrooxidation

Direct alcohol fuel cells (DAFCs) are powered by the alcohol electro-oxidation reaction (AOR), where an electrocatalyst with an optimal electronic structure can accelerate the sluggish AOR. Interestingly, strain engineering in hetero-catalysis offers a promising route to boost their catalytic activity. Herein, we report on a class of monodispersed ultrathin twisty PdBi alloy nanowires (TNWs) assemblies with face-centered structures that drive AORs. These thin nanowire structures expose a large number of reactive sites. Strikingly, Pd6Bi1 TNWs show an excellent current density of 2066, 3047, and 1231 mA mgPd−1 for oxidation of ethanol, ethylene glycol, and glycerol, respectively. The “volcano-like” behaviors observed on PdBi TNWs for AORs indicate that the maximum catalytic mass activity is a well balance between active intermediates and blocking species at the interface. This study offers an effective and universal method to build novel nanocatalysts in various applications by rationally designing highly efficient catalysts with specific strain.

Organic Heterocyclic Strategy for Precisely Regulating Electronic State of Palladium Interface to Boost Alcohol Oxidation

AbstractExploring highly‐efficient palladium (Pd)‐based electrocatalysts for the alcohol oxidation reaction (AOR) is crucial yet challenging for chemists due to the vague Pd interface with an uncontrollable electronic environment. Herein, an organic heterocyclic strategy is used for the first time to modulate the electronic state of Pd electrocatalysts by anchoring Pd nanoparticles to conjugated microporous polymers (CMPs) with varied S‐, N‐, O‐, or S, N‐heterocycles. Among these CMPs, the S, N‐containing thiazole heterocyclic polymer SNC with Pd catalyst exhibits highly‐efficient current densities of 1575.0 mA mgPd−1 for methanol oxidation and 1071.0 mA mgPd−1 for ethanol oxidation, which are among the highest performance in the heterocyclic modulated Pd systems and surpass the commercial Pd black catalyst. Detailed theory calculations suggest that although the furan (O‐heterocycle) polymer OC has the strongest charge transfer (0.057 |e|) with the Pd cluster, the moderate electron transfer (0.041 |e|) of the Pd/SNC heterojunction with an S···N···Pd noncovalent interaction shows the best catalytic reaction kinetics. Moreover, the d‐band of the Pd/SNC system is closer to the volcano vertex than its counterparts. These results indicate that appropriate electron transfer intensity regulation of Pd electronic state by well‐defined heterocyclic structures may significantly improve AOR activity.

Pd3Co1 Alloy Nanocluster on the MWCNT Catalyst for Efficient Formic Acid Electro-Oxidation

In this study, the Pd3Co1 alloy nanocluster from a multiwalled carbon nanotube (MWCTN) catalyst was fabricated in deep eutectic solvents (DESs) (referred to Pd3Co1/CNTs). The catalyst shows a better mass activity towards the formic acid oxidation reaction (FAOR) (2410.1 mA mgPd-1), a better anti-CO toxicity (0.36 V) than Pd/CNTs and commercial Pd/C. The improved performance of Pd3Co1/CNTs is attributed to appropriate Co doping, which changed the electronic state around the Pd atom, lowered the d-band of Pd, formed a new Pd-Co bond act at the active sites, affected the adsorption of the toxic intermediates and weakened the dissolution of Pd; moreover, with the assistance of DES, the obtained ultrafine Pd3Co1 nanoalloy exposes more active sites to enhance the dehydrogenation process of the FAOR. The study shows a new way to construct a high-performance Pd-alloy catalyst for the direct formic acid fuel cell.

Pd12Ag1 nanoalloy on dendritic CNFs catalyst for boosting formic acid oxidation

In this study, dendritic carbon nanofibers (CNFs) loaded with Pd12Ag1 nanoalloy were prepared as a catalyst using a one-pot method. The average particle size of the Pd12Ag1 nanoalloy is 4.2 nm, which is uniformly dispersed over the surface of the CNFs. The Pd12Ag1/CNFs catalyst has the best performance for formic acid oxidation (FAO), with catalytic activity (2825.0 mA mgPd−1) and durability after 7200 s (70.6 mA mgPd−1) up to 5.25 and 10.87 times, respectively, compared with commercial Pd/C. The improved electrocatalytic performance of the Pd12Ag1/CNFs catalyst is attributed to the appropriate Ag doping, which changes the electronic state around the Pd atom, forming two new active sites (Pd-Pd and Pd-Ag); on the other hand, the special structure and rough surface of CNFs expose more active sites to enhance the dehydrogenation process of FAO. Furthermore, Pd13, Ag13, and Pd12Ag1 clusters loaded on the surface of defect-free graphene (DG) and single vacancy defective graphene (SVG) were simulated using density functional theory (DFT) to confirm the effect of different carbon materials and doped metals on the overall catalyst at the atomic level.

Assembly of trimetallic palladium-silver-copper nanosheets for efficient C2 alcohol electrooxidation

The synthesis of two-dimensional (2D) alloyed efficient electrocatalysts with several active sites has attracted considerable attention in recent years. In this work, trimetallic palladium-silver-copper (PdAgCu) nanosheet assemblies (NSAs) are synthesized in the presence of cetyltrimethylammonium bromide and molybdenum hexacarbonyl as the structure-directing agents. The morphologies and structures of the trimetallic PdAgCu NSAs are identified by high-angle annular dark-field scanning transmission electron microscopy, transmission electron microscopy, and X-ray diffraction. The trimetallic Pd6Ag3Cu2 NSA has high electrocatalytic performance with outstanding long-term stabilities for ethylene glycol oxidation reaction (EGOR = 5696 mA mgPd−1) and ethanol oxidation reaction (EOR = 4374 mA mgPd−1). The enhanced electrocatalytic activities can be attributed to the synergistic effects, including strain, ligand, and bifunctional effects. Furthermore, the electrocatalytic mechanisms of the trimetallic electrocatalysts toward C2 alcohols are determined, and high concentrations of OH− and C2 alcohols favor EGOR and EOR.

Cyanogel‐Induced PdCu Alloy with Pd‐Enriched Surface for Formic Acid Oxidation and Oxygen Reduction

Pd‐based catalysts with preferred morphologies and compositions are of great significance for boosting oxygen reduction reaction (ORR) and formic acid oxidation reaction (FAOR) performance, but the development of facile preparation methods is challenging. Therefore, an unconventional strategy is proposed to synthesize palladium‐copper cyanogel (Cux[Pd(CN)4]y·aH2O) and subsequently induce the formation of PdCu alloy nanocorals (ANCs), which has the advantages of being simple, green, and efficient. The synthesized PdCu ANCs consist of a 3D porous network structure and Pd‐enriched surface, which is beneficial to exposing more accessible active sites, accelerating mass/electron transfer rate, and strengthening chemical stability. By virtue of these merits, the PdCu ANCs exhibit superior activity and stability in both FAOR and ORR. Remarkably, the mass activity of PdCu ANCs catalyst in FAOR reaches 554.53 mA mgPd−1, with a 4.8‐fold enhancement compared to commercial Pd black. And the half‐wave potential of 0.861 V of PdCu ANCs catalyst in ORR surpasses the values of commercial Pd black and Pt black catalysts.

Precisely Tuning the Surface Nanostructure of Ni@Pd Nanocatalysts for Enhanced Formic Acid Oxidation

AbstractConstructing Ni@Pd nanocatalysts can effectively improve the catalytic efficiency of Pd atoms. However, it is difficult to grow Pd atoms uniformly on the Ni surface due to the large lattice mismatch between Ni and Pd. Herein, we demonstrate that the well‐defined Ni@Pd nanocatalysts can be obtained by the galvanic replacement reaction between Ni and Pd at room temperature. By simply regulating the content of Pd precursor in the galvanic replacement reaction, the atomic percentages of Pd can be controlled from 2 % to 9 %. In synthesized Ni@Pd nanocatalysts, the Ni@Pd0.06 core‐shell nanocrystals show the highest mass activity (1186 mA mgPd−1) and specific activity (4.21 mA cm−2), which are 5.6 times and 2.6 times higher than that of the commercial Pd/C nanocatalyst (212 mA mgPd−1, 1.60 mA cm−2). The enhanced performance is mainly attributed to the synergistic effect between Pd and Ni and the core‐shell nanostructure.