Pd-Ni Alloys Research Articles

Selective catalytic hydrodeoxygenation of vanillin to 2-Methoxy-4-methyl phenol and 4-Methyl cyclohexanol over Pd/CuFe2O4 and PdNi/CuFe2O4 catalysts

The development of a sustainable catalytic process for the hydrodeoxygenation of lignin model compounds to renewable fuels and chemicals is essential to meet the requirement of a fossil-fuel-free modern society. Herein a Pd/CuFe2O4 and bimetallic PdNi/CuFe2O4 catalysts were developed for the hydrodeoxygenation of vanillin to 2-methoxy-4-methylphenol (MMP) and 4-methyl cyclohexanol (4-MC), respectively. The Pd/CuFe2O4 provided selective catalytic transfer hydrodeoxygenation of vanillin to MMP with isopropanol (IPA). The synergistic participation of Pd NPs and CuFe2O4 (1Pd/CuFe2O4) afforded 99.4% vanillin conversion and 99.2% MMP selectivity at 150 °C. The acidity of the catalyst facilitated the efficient adsorption of vanillin and IPA, and the high dispersion of Pd NPs lowered the hydrogen abstraction barrier of IPA to facilitate the transformation. Then Ni was incorporated into Pd/CuFe2O4 to produce 4-methyl cyclohexanol from vanillin. The interfacial interaction between Pd and Ni over CuFe2O4 (1Pd7Ni/CuFe2O4) provided 95.8% 4-methyl cyclohexanol (4-MC) in H2 (20 bar) at 180 °C. The acidity of the catalyst, formation of Pd-Ni alloys, and efficient adsorption of vanillin and MMP were responsible for the high activity of the catalyst towards 4-methyl cyclohexanol (4-MC) production. Density functional theory (DFT) calculations were also performed to elucidate the reaction mechanism for vanillin transformation to MMP and 4-MC on the Pd/CuFe2O4 and bimetallic PdNi/CuFe2O4 catalysts.

Effect of the thermodynamic factor on the intrinsic and tracer diffusivities in binary mixtures.

One of the Darken equationsgives a relationship between the intrinsic and the tracer diffusion coefficients, D_{A} and D_{A}^{*}, of species A in a solid binary mixture. In its original formulation, the equationreads D_{A}=D_{A}^{*}Γ, with Γ the thermodynamic factor. The question addressed in this paper is how D_{A} and D_{A}^{*} depend separately on Γ. Using a recent result for transition probabilities in terms of the excess chemical potential [M. Di Muro and M. Hoyuelos, Phys. Rev. E 104, 044104 (2021)2470-004510.1103/PhysRevE.104.044104], it is shown that the intrinsic diffusivity does not depend on Γ. This approach simplifies a previous theoretical analysis that reaches the same result. Experimental results of diffusion in Ni-Pd and Fe-Pd alloys [M. J. H. van Dal et al., Acta Mater. 48, 385 (2000)1359-645410.1016/S1359-6454(99)00375-4] are used to check the theory. Numerical simulations of Ni-Pd were performed to show that the migration energy is the main factor responsible for the increase in diffusivity at intermediate concentrations.

Enhanced Activity of WOx-Promoted PdNi Nanoclusters Confined by Amino-Modified KIT-6 for Dehydrogenation of Additive-Free Formic Acid

Formic acid (FA, HCOOH), featured as a major liquid product of biomass processing and especially a liquid sunshine carrier, thus becomes a renewable and promising liquid organic hydrogen carrier. It is highly desirable, but it remains a big challenge to develop a highly active heterogeneous catalyst with no or low content of noble metals for dehydrogenation of additive-free FA at ambient conditions. Herein, for the first time, WOx-modified PdNi alloy nanoclusters immobilized by amino-functionalized KIT-6 (PdNi-WOx/KIT-6-NH2) are prepared through a simple and facile strategy at ambient conditions. PdNi-WOx clusters with an ultrasmall size of 1.4 nm are highly dispersed onto KIT-6-NH2 support. The strong electronic coupling in PdNi-WOx NCs and electronic metal–support interaction between PdNi-WOx NCs and KIT-6-NH2 support lead to the formation of electron-rich PdNi of PdNi-WOx/KIT-6-NH2. The resulting PdNi-WOx/KIT-6-NH2 catalyst exhibits highly efficient catalytic activity and 100% hydrogen selectivity for formic acid dehydrogenation without extra additives, giving turnover frequency (TOF) values of 1699 h–1 at 303 K and 4417 h–1 at 323 K, which is higher than most of the heterogeneous catalysts ever reported. Kinetic isotope effect investigation clearly shows that C–H bond cleavage is the rate-determining step for PdNi-WOx/KIT-6-NH2. This work provides a new insight into designing low-cost and efficient heterogeneous catalysts for dehydrogenation of formic acid.

High hydrogen selectivity Pd-Ni alloy film hydrogen sensor with hybrid organosilica membranes

Hydrogen sensors are very important for real-time detection of hydrogen leakage. In this study, a Pd-Ni film hydrogen sensor with high hydrogen response and selectivity was fabricated. A 1.3 µm-thick organosilica membrane was coated on the surface of Pd-Ni alloy film by sol-gel process and hot-coating method to fabricate a 1,2-bis(triethoxysilyl)methane (BTESM)-coated Pd-Ni film hydrogen sensor, which endows the sensor with superior H2 selectivity due to the molecular sieve property. And the gas sensing performance was tested at optimum operating temperature. The results show higher response is obtained in both N2 and air atmosphere by hybrid organosilica membrane modification on the Pd-Ni film sensor. Very importantly, the response of the sensor to hydrogen is greatly improved and well maintained in the presence of oxygen, although the response/recovery time increased. The organosilica membrane has high permeability to hydrogen with the kinetic dimater of 0.289 nm while effectively inhibits the permeation of relatively larger gas molecule such as oxygen (0.34 nm) and methanol (0.38 nm), resulting in excellent selectivity to H2. The mechanism of response and selectivity enhancement is explored.

Hierarchical PdNi alloy nanochains coupled with Ni(OH)2 nanosheets to enhance CO-poisoning resistance for the methanol oxidation reaction.

Hybridizing Pd-based electrocatalysts with Ni-based species has been recognized as an effective pathway to enhance the catalytic performance for the methanol oxidation reaction (MOR). However, doping Ni-based species with heterogeneous valences into Pd nanocrystals still remains challenging, although heterogeneous valence Ni species may result in improved properties of Pd from different aspects. Herein, a facile one-pot synthetic method is reported to simultaneously introduce alloyed Ni0 into Pd lattices and couple hydroxy Ni2+ species with a Pd surface, generating 1D porous PdNi alloy nanochains@Ni(OH)2 nanosheet hybrids (PdNi NCs@Ni(OH)2 NSs). Borane-tert-butylamine (C4H14BN) plays the key role in realizing the formation of Ni-based species with heterogeneous valence. On one hand, it works as a reducing agent to facilitate the doping of alloyed Ni0 into the lattice of Pd nanochains. On the other hand, it raises the solution pH value and converts the remaining [Ni(CN)4]2- into Ni(OH)2 nanosheets. Each component of the PdNi NCs@Ni(OH)2 NSs plays an important role: Pd serves as the active site, alloyed Ni0 modifies the electronic structure of Pd, and Ni(OH)2 provides abundant OHads species to strengthen the anti-poisoning capability, thus greatly enhancing the activity, CO-tolerance, and durability for the MOR.

Effect of annealing treatment on response characteristics of Pd-Ni alloy based hydrogen sensor

The response rate and anti-interference performance are crucial to the detect performance for Pd-based hydrogen sensors. In this study, a resistance- type palladium-nickel (Pd90Ni10) thin film hydrogen sensors were prepared by the ion beam sputtering method. Sensors with an optimized Pd90Ni10 thickness (90 nm) which showed the fastest response for hydrogen were selected to study the effect of annealing treatment to the response rate and anti-interference performance. Four groups of samples were annealed at 250°C, 300°C, 350°C, and 400°C in air atmosphere for 4 hours, respectively. The impact of annealing treatment on base resistance stability and hydrogen response characteristics were studied. SEM, EDS and XRD analysis were carried out to reveal the relationship between response characteristics and microstructures. Results show that annealing treatment was beneficial to the base resistance stability and response rate. Samples annealed at 350°C showed the best base resistance stability and response rate. Furthermore, the difference of response rate ∆ was improved for the annealing treatment, indicating the improvement of the hydrogen sensor regarding the anti-interference effect to other gases. Meanwhile, a new mechanism including mutli-factors of Pd-Ni alloy about the anti-interference of oxygen was proposed based on our study. Besides, the sensors with the optimized fabrication process were tested in mixed standard gas with various hydrogen concentrations. This work provides an outstanding guidance to fabricate of hydrogen sensors of high response rate and anti-interference performance.

Potentiostatic Dealloying Fabrication and Electrochemical Actuation Performance of Bulk Nanoporous Palladium

Metallic actuators increasingly exhibit superiority over conventional actuators (such as piezoelectric ceramics) via low energy consumption and large strain amplitude. Large strain amplitude and high strain energy density (or work density) are required for an actuator with excellent comprehensive performance. Herein, we fabricated bulk nanoporous Pd (np-Pd) with a dense nanoporous structure by two-step potentiostatic dealloying of as-annealed Ni–Pd alloy with chemical corrosion resistance, and investigated the dealloying behaviors as well as electrochemical actuation performance. A visible current density oscillation occurred during dealloying, which is related to formation/dissolution of the passivating film. Additionally, since the dense and continuous ligaments establish a good network connectivity for large strain response, the np-Pd achieves a strain amplitude of up to 3.74% and high strain energy density, which stands out among many actuator materials (e.g., np-AuPt, np-Ni, and np-AlNiCu). Our study provides a useful guidance for fabricating metallic actuators with excellent comprehensive performance.

PdNi Nanoframework and Nanochain Catalysts with Enhanced Oxygen Reduction Reaction Performance

AbstractThe development of Pt‐free nanocatalysts with enhanced electrocatalytic activity and durability is essential for the commercialization of fuel cells. Herein, we report a new class of active and durable PdNi nanocatalysts for the oxygen reduction reaction (ORR) in an alkaline medium. PdNi nanoframework (PdNi‐NF), consisting of interconnected ultrathin ridges was synthesized through a galvanic replacement reduction (GRR) strategy using Ni nanoparticles, obtained by radiolytic reduction, as seeds. PdNi nanochain (PdNi‐NC), composed of aggregated nanoparticles, was produced by one‐pot γ‐radiation induced reduction. It was found that the carbon‐supported PdNi‐NF catalysts exhibit higher ORR activity and enhanced durability compared to PdNi‐NC/C (PdNi‐NC on carbon), Pd‐NP/C (Pd nanoparticle on carbon), and commercial Pt/C catalysts. The superior activity of PdNi‐NF/C catalyst may originate from the nanoframework morphology that facilitates the O2 diffusion and the electronic effect induced by the sub‐surface PdNi alloy; the improved durability can be ascribed to the stable Pd‐enriched surface layer.

Enhanced activity of bimetallic Pd-Ni nanoparticles on KIT-6 for production of hydrogen from dodecahydro-N-ethylcarbazole

The development of catalysts with excellent dehydrogenation performance is the key to solving the problem of slow dehydrogenation and high temperature in the liquid organic hydrogen carrier hydrogen storage cycle. The bimetallic Pd-Ni/K6 catalyst was prepared by inorganometallic chemistry adsorption (ICA) and ultrasonic-assisted isopropanol reduction. Pd(NH3)42+and Ni2+will be anchored at the location of silanol groups (Si-OH) on the surface of KIT-6 (K6) by ICA, which prevents the aggregation of bimetallic Pd-Ni nanoparticles (NPs) during ultrasonic reduction. The HADDF-STEM results showed that Pd-Ni NPs with an average particle size of 2.1 nm were uniformly dispersed on the K6 surface. Pd-Ni alloy structure was found in Pd4Ni1/K6, and there was obvious electron transfer from Ni to Pd. The small Pd-Ni NPs, the electronic interaction of bimetallic Pd-Ni NPs, and the lattice defects caused by the Pd-Ni alloy enhance the activity of Pd4Ni1/K6 for H12-NEC dehydrogenation. At 180°C, the hydrogen productivity over Pd4Ni1/K6 is 1.7 times higher than that of Pd/K6. The complexation of Pd and Ni with O of Si-OH stabilized Pd-Ni NPs and prevented their agglomeration and leaching. Pd4Ni1/K6 showed excellent cycle stability, and the dehydrogenation efficiency remained above 90 % after 5 cycles.

Core–Shell CuPd@NiPd Nanoparticles: Coupling Lateral Strain with Electronic Interaction toward High-Efficiency Electrocatalysis

Geometric structure and chemical composition are two critical factors that determine the electronic properties of an active metal favorable for a given catalytic reaction. In this scenario, we develop a wet-chemistry method to construct core–shell nanoentities consisting of a CuPd alloy core and a NiPd alloy shell, termed as CuPd@NiPd, which involves the synthesis of CuNi alloy seeds, and a subsequent galvanic replacement reaction with Pd2+ precursors in an organic medium at elevated temperature. In these unique core–shell nanostructures, the compressive lattice strain between core and shell regions and the electronic interaction between Pd and transitional elements could be coupled together to lead to a downshift of the d-band center of Pd sites, thus endowing them with good activity for catalyzing ethanol oxidation reaction (EOR) and oxygen reduction reaction (ORR). In particular, at an appropriate Pd/Cu precursor ratio of 1/1, the as-prepared core–shell CuPd@NiPd nanoparticles exhibit a mass activity of 5.1 A mg–1 for EOR and a half-wave potential of 0.91 V for ORR at room temperature in an alkaline medium, outperforming alloy CuPd, NiPd counterparts, commercial Pd/C, and the vast majority of recently reported Pd-based electrocatalysts.

Stability, Energetic, and Reactivity Properties of NiPd Alloy Clusters Deposited on Graphene with Defects: A Density Functional Theory Study.

Graphene with defects is a vital support material since it improves the catalytic activity and stability of nanoparticles. Here, a density functional theory study was conducted to investigate the stability, energy, and reactivity properties of NinPdn (n = 1–3) clusters supported on graphene with different defects (i.e., graphene with monovacancy and pyridinic N-doped graphene with one, two, and three N atoms). On the interaction between the clusters and graphene with defects, the charge was transferred from the clusters to the modified graphene, and it was observed that the binding energy between them was substantially higher than that previously reported for Pd-based clusters supported on pristine graphene. The vertical ionization potential calculated for the clusters supported on modified graphene decreased compared with that calculated for free clusters. In contrast, vertical electron affinity values for the clusters supported on graphene with defects increased compared with those calculated for free clusters. In addition, the chemical hardness calculated for the clusters supported on modified graphene was decreased compared with free clusters, suggesting that the former may exhibit higher reactivity than the latter. Therefore, it could be inferred that graphene with defects is a good support material because it enhances the stability and reactivity of the Pd-based alloy clusters supported on PNG.

Active site and adsorption behavior engineering of subsize PdNi nanoparticles for boosting electrocatalytic hydrodechlorination of 4-chlorophenol

Developing an efficient strategy to engineer the removal efficiency of catalysts for electrocatalytic hydrodechlorination (ECH) of acute toxic chlorophenols is of considerable importance but remains challenging. We report herein an efficient strategy to modulate the active site and adsorption behaviors of PdNi alloy nanoparticles (NPs) anchored on oxygen/nitrogen-doped porous carbon nanosheets (PdNi/NPCNs) through nanopore trapping. The competitive adsorption of PdCl42- and Ni2+ ions and subsequent reduction belowrmodynamic reduction temperature ensure the formation of highly dispersed subsize PdNi alloy NPs on the surface of NPCNs. More significantly, alloying of Pd with Ni not only provides abundant surface-active sites but also adjusts the adsorption behaviors of intermediates over PdNi/NPCNs because of the strong electronic interaction between the two metals, thereby considerably boosting the ECH performance for 4-chlorophenol (4-CP) removal. The complete removal of 4-CP (100 mg L−1) is achieved at 7.5 mA within 180 min, superior to that of monometallic Pd/NPCNs and many previous electrodes reported thus far. The catalyst also exhibits boosted stability toward the ECH of 4-CP with five successive recycling runs. This study provides an effective strategy to fabricate high-performance electrocatalysts for ECH reaction, which shows great promise in potential applications.

NiPd nano-alloy film as a promising low overpotential electrocatalyst for high activity water oxidation reaction

Electrolytic water splitting is promising strategy for the production of Green Hydrogen (H2) but the sluggish kinetics during the oxygen evolution reaction (OER) is still a challenge. Herein, nickel palladium (NiPd) electrocatalyst has been presented for energy-efficient water oxidation. The catalyst films have been deposited on nickel foam (NF) substrate using a single-step aerosol-assisted chemical vapor deposition technique. The thickness of the deposited film is controlled by varying the deposition time from 60 to 180 min. The morphology and structure of the NiPd catalysts were characterized and directly employed for OER investigation in 1.0 M KOH. The catalyst made for 120 min initiates OER at an extremely low onset potential of 1.4 V vs. RHE (η = 170 mV), requires an overpotential of just 180 mV to approach the benchmark current density of 10 mA cm-2 and peak current density of > 1300 mA cm-2 is achieved at an overpotential of mere 370 mV. Moreover, the catalyst demonstrates excellent durability during prolonged water electrolysis experiments and imposing kinetics for OER. The catalytic performance of NiPd electrode is many folds better than the star catalyst (IrO2) investigated under similar circumstances. The superior OER activity of NiPd alloy at such low overpotentials is accredited to the mutual relevance of high electroactive sites at intermetallic catalyst surface, the favorable synergy created between intrinsically active 3d-transition metal Ni and noble metal, Pd grown over porous and conductive NF surface that cumulatively favors electronic communications and adsorption/desorption process at nano surfaces of the catalytic film.

Water purification from chlorobenzenes using heteroatom-functionalized carbon nanofibers produced on self-organizing Ni-Pd catalyst

The development of effective methods for the processing of hazardous wastes containing chlorinated hydrocarbons still remains a big challenge. Herein, the approach allowing the transformation of chlorohydrocarbons into functionalized carbon nanomaterials was demonstrated for 1,2-dichloroethane (DCE) used as a model compound. Carbon nanofibers (CNF) doped with nitrogen and oxygen heteroatoms were fabricated by a joint decomposition of DCE and co-reagent (CH3CN, NH4OH, C2H5OH, and H2O). The Ni-Pd (5%) alloy was used as a catalyst precursor for the CNF synthesis. Pristine Ni-Pd alloy was found to undergo disintegration under the reaction conditions and to induce an active growth of the functionalized carbon nanofibers. The obtained CNF were shown to have a similar segmental structure of carbon filaments and to possess high specific surface area (up to 470 m2/g) and porosity (up to 0.9 cm3/g). According to X-ray photoelectron spectroscopy data, the nitrogen content within CNF samples prepared using N-comprising precursors was about 1.0–1.7 at%. The total oxygen content reaches 3.6 at%. The obtained materials were demonstrated to be attractive for the dichlorobenzene adsorption from its aqueous solutions.

In-situ synthesis of nickel/palladium bimetal/ZnIn2S4 Schottky heterojunction for efficient photocatalytic hydrogen evolution

Coupling with bimetallic nanoparticles (NPs) has been considered as a promising strategy to enhance photocatalytic hydrogen evolution (PHE) efficiency of semiconductor photocatalysts and simultaneously minimize the use of expensive noble metals. Herein, we firstly synthesized spherical-like ZnIn2S4 (ZIS) by a solvothermal method, and then combined with nickel/palladium (denoted as NiPd) bimetallic NPs to form NiPd bimetal/ZIS Schottky heterojunction. The chemical states of NiPd NPs were confirmed in the form of NiPd bimetal rather than Ni–Pd alloy. The detailed characterization results demonstrated that the deposition of NiPd bimetal played a major role in increasing light harvesting capacity, accelerating charge carrier (electrons and holes) separation and facilitating photogenerated electrons transfer, leading to the boosted PHE performance in NiPd-ZIS photocatalysts. By adjusting Ni:Pd molar ratio in NixPdy-ZIS photocatalysts, the desired sample of Ni3Pd7-ZIS exhibited the highest PHE efficiency (106.6 µmol/h) and apparent quantum yield (AQY) value of 40.22% at 400 nm under visible light as compared to ZIS, Ni-ZIS and Pd-ZIS. The multiple techniques were performed to deeply investigate the photogenerated charge carrier separation, transfer and recombination. The possible mechanism over Ni3Pd7-ZIS sample for boosting PHE performance was presented based on characterization results. On the whole, this work would provide some insights into the development of cost-effective and high-efficiency bimetallic cocatalyst-based photocatalysts.

High performance self-supporting 3D nanoporous PdNi alloy foam for methanol oxidation electrocatalysis

High performance self-supporting 3D nanoporous PdNi alloy foam for methanol oxidation electrocatalysis

In situ synthesis by organometallic method of vulcan supported PdNi nanostructures for hydrogen evolution reaction in alkaline solution

Pd and Pd-based catalysts for hydrogen production remain the best alternative to Pt substitution because of similarities in their electronic structure and more abundant reserves. In this work, it was carried out the in-situ synthesis of Pd x Ni 1-x /C electrode materials (x = 0, 30, 50, 70 and 100 wt%) by the displacement of ligands from organometallic compounds followed by an annealing process at 300 °C in Ar atmosphere. The electrocatalytic performance of these materials was evaluated on the hydrogen evolution reaction in alkaline medium (1 M KOH). The results showed that annealing process, after the synthesis of stabilized nanostructures by organometallic method, did not affect the particle size (4.27 ± 1.14 to 4.62 ± 1.59 nm) and dispersion (25.75–27.07%) of the alloyed nanostructures. The modification of Pd electronic features with low Ni amount facilitates the adsorption of the hydrogen on the bimetallic active surface of the catalysts. The PdNi alloys, especially Pd 70 Ni 30 /C, tend to display the overpotential of HER to more positive values in comparison with Pd/C catalysts. This behavior is clearly correlated with an improvement by the synergistic effect between the components, which in turn enhance the electrochemical surface area (ECSA) and the real area. Either the hydrogen adsorption resistance and charge transfer resistance are dependent of the Ni amount, due to Ni influences ion/atom recombination or hydrogen desorption. • Stabilized particles of binary Pd x Ni 1-x alloys by organometallic compounds method. • Annealing process does not affect particle size, stabilization and dispersion. • Ni incorporation provokes a displacement in fcc peaks confirming alloy formation. • Pd 70 Ni 30 /C display more positive HER overpotentials in comparison with Pd/C.

One-pot functionalization of catalytically derived carbon nanostructures with heteroatoms for toxic-free environment

Nowadays, catalytic methods of utilization of industrial organic wastes are widely developing. Chlorinated hydrocarbons represent the most important class of substances, which should be efficiently converted into value-added product, e.g., carbon nanostructures. Present work demonstrates results of comprehensive investigation and characterization of the electronic state of all elements composing the structure of functionalized carbon nanomaterials obtained via catalytic decomposition of 1,2-C2H4Cl2 and co-substrates (acetonitrile, ethanol, NH4OH) over Ni-Pd alloy using high-resolution synchrotron-based X-ray photoelectron spectroscopy along with NEXAFS spectroscopy. This study is focused on a deeper understanding of reactions proceeding on surface of catalytic particles. Obtained data make it possible for the transition from the description of the nature of chemical reactions to target and controllable tailoring of the molecular structure of carbon nanostructures emergent as a result of complex chemical process realization. The maximum content of chlorine atoms bound to carbon was observed for the sample obtained via decomposition of pure 1,2-C2H4Cl2. Presence of C2H5OH slightly decreases the proportion of Cl-atoms chemically bound to carbon. A more considerable effect was observed when CH3CN vapors were added. The strongest impact on process and defectiveness of the carbon material was ascertained for NH4OH, when the number of C-Cl atoms reached 75.1%.

Strain Relaxation in Metal Alloy Catalysts Steers the Product Selectivity of Electrocatalytic CO2 Reduction.

Strain engineering in bimetallic alloy structures is of great interest in electrochemical CO2 reduction reactions (CO2RR), in which it simultaneously improves electrocatalytic activity and product selectivity by optimizing the binding properties of intermediates. However, a reliable synthetic strategy and systematic understanding of the strain effects in the CO2RR are still lacking. Herein, we report a strain relaxation strategy used to determine lattice strains in bimetal MNi alloys (M = Pd, Ag, and Au) and realize an outstanding CO2-to-CO Faradaic efficiency of 96.6% and show the outstanding activity and durability toward a Zn-CO2 battery. Molecular dynamics (MD) simulations predict that the relaxation of strained PdNi alloys (s-PdNi) is correlated with increases in synthesis temperature, and the high temperature activation energy drives complete atomic mixing of multiple metal atoms to allow for regulation of lattice strains. Density functional theory (DFT) calculations reveal that strain relaxation effectively improves CO2RR activity and selectivity by optimizing the formation energies of *COOH and *CO intermediates on s-PdNi alloy surfaces, as also verified by in situ spectroscopic investigations. This approach provides a promising approach for catalyst design, enabling independent optimization of formation energies of reaction intermediates to improve catalytic activity and selectivity simultaneously.

Ultrathin Twisty PdNi Alloy Nanowires as Highly Active ORR Electrocatalysts Exhibiting Morphology-Induced Durability over 200 K Cycles.

Even though the anion exchange membrane fuel cells have many advantages, the stability of their electrocatalysts for oxygen reduction reaction (ORR) has remained remarkably poor. We report here on the ultrathin twisty PdNi-alloy nanowires (NWs) exhibiting a very low reaction overpotential with an E1/2 ∼ 0.95 V versus RHE in alkaline media maintained over 200 K cycles, the highest ever recorded for an electrocatalyst. The mass activity of the used NWs is >10 times higher than fresh commercial Pt/C. Therein, Ni improves the Pd d-band center for a more efficient ORR, and its leaching continuously regenerates the surface active sites. The twisty nanowire morphology imparts multiple anchor points on the electrode surface to arrest their detachment or coalescence and extra stability from self-entanglement. The significance of the NW morphology was further confirmed from the high-temperature durability studies. The study demonstrates that tailoring the number of contact points to the electrode-surface may help realize commercial-grade stability in the highly active electrocatalysts.