PtNi Nanoparticles Research Articles

Modulating Electronic Metal-Support Interactions to Boost Visible-Light-Driven Hydrolysis of Ammonia Borane: Nickel-Platinum Nanoparticles Supported on Phosphorus-Doped Titania.

Ammonia borane (AB) is a promising material for chemical H2 storage owing to its high H2 density (up to 19.6 wt %). However, the development of an efficient catalyst for driving H2 evolution through AB hydrolysis remains challenging. Therefore, a visible-light-driven strategy for generating H2 through AB hydrolysis was implemented in this study using Ni-Pt nanoparticles supported on phosphorus-doped TiO2 (Ni-Pt/P-TiO2 ) as photocatalysts. Through surface engineering, P-TiO2 was prepared by phytic-acid-assisted phosphorization and then employed as an ideal support for immobilizing Ni-Pt nanoparticles via a facile co-reduction strategy. Under visible-light irradiation at 283 K, Ni40 Pt60 /P-TiO2 exhibited improved recyclability and a high turnover frequency of 967.8 mol molPt -1 min-1 . Characterization experiments and density functional theory calculations indicated that the enhanced performance of Ni40 Pt60 /P-TiO2 originated from a combination of the Ni-Pt alloying effect, the Mott-Schottky junction at the metal-semiconductor interface, and strong metal-support interactions. These findings not only underscore the benefits of utilizing multipronged effects to construct highly active AB-hydrolyzing catalysts, but also pave a path toward designing high-performance catalysts by surface engineering to modulate the electronic metal-support interactions for other visible-light-induced reactions.

Electron Regulation in Pt-M (M = Cu, Co, and Ni) Decorated WO3 Thin Films for Photocatalytic Degradation Performance

In this study, Pt-M/WO3 (M = Cu, Co, and Ni) thin films are effectively synthesized by preparing homogeneous precursor sols, spin-coating, toluene-etching, and calcination. Furthermore, the microstructural, chemical, and electrochemical properties of the WO3, Pt-Cu/WO3, Pt-Co/WO3, and Pt-Ni/WO3 thin films are also systematically compared. The results demonstrate that when compared to the WO3 thin film, the photocatalytic capability for methylene blue (MB) solution degradation is greatly increased in the Pt-M/WO3 thin films. Transfer routes for photogenerated charges and an improved photocatalytic process are suggested based on the experimental results. Due to the large difference in the work function (Φ) between the bimetallic alloy Pt-M and WO3, a bending of the energy bands at the Pt-M/WO3 interface is presented. Furthermore, the introduction of transition metals such as Cu, Co, or Ni modifies the electronic structure of Pt-M/WO3 thin films, facilitating the separation and migration of electrons and holes. Specifically, the photogenerated electrons migrate from the CB of WO3 to Pt-Co or Pt-Ni nanoparticles in the samples of Pt-Co/WO3 or Pt-Ni/WO3 thin films, while the hot electrons from the localized surface plasmon resonance (LSPR) effect of Cu could transfer to the conduction band (CB) of WO3 and other electrons generated from the photoexcitation of the WO3 semiconductor itself in the sample of the Pt-Cu/WO3 thin film. In summary, this work proposes a unique strategy for creating electron regulation in Pt-M decorated WO3 thin films for photocatalytic application.

Printed, Flexible, Ionic Liquid-Based Hydrogen Sensor via Aerosol Jet Printing of Nanomaterials

Low-cost, high-performance hydrogen sensors are highly demanded in hydrogen leakage detection. To increase the sensitivity and reliability of the hydrogen sensor, an ionic liquid (IL)-based electrochemical gas sensor is fabricated with bimetallic Platinum–Nickel (Pt-Ni) nanoparticles (NPs) with aerosol jet printing technology for continuous monitoring of hydrogen concentration. The Pt-Ni NPs covering the top surface of the metal electrodes can accelerate the catalysis and expand the sensing surface area. When hydrogen gas is sensed at room temperature, the uniquely reversible and rapid redox reactions of hydrogen at the IL/Pt electrode interface, thereby creating continuous measurement capability in a real-time manner with little signal drift. The full coverage of the sensor electrodes will increase the robustness and accuracy of the device. The fabricated sensors demonstrate excellent analytical sensing performance, reaching a limit of detection up to 19.3 ppm. The device takes advantage of an easy fabrication process, simple structure, high sensing response, and low cost, providing a promise for hydrogen sensing at room temperatures.

Post-Synthesis Heat Treatment of Doped PtNi-Alloy Fuel-Cell Catalyst Nanoparticles Studied by In-Situ Electron Microscopy

Octahedral-shaped PtNi-alloy nanoparticles are highly active oxygen reduction reaction catalysts for the cathode in proton exchange membrane fuel cells. However, one major drawback in their application is their limited long-term morphological and compositional stability. Here, we present a detailed in situ electron microscopy characterization of thermal annealing on octahedral-shaped PtNi catalysts as well as on doped octahedral PtNi(Mo) and PtNi(MoRh) catalysts. The evolution of their morphology and composition was quantified during both ex situ and in situ experiments using energy dispersive X-ray spectroscopy in a scanning transmission electron microscope under a hydrogen atmosphere and in vacuum. Morphological changes upon heating, i.e., a gradual loss of the octahedral shape and a continuous rounding of the particles, were observed, as well as evidence for increased alloying. Furthermore, the evolution of the shape of the PtNi(Mo) nanoparticles was quantified using in situ experiments under hydrogen atmosphere in a transmission electron microscope. The shape change of the particles was quantified using segmentation maps created by a neural network. It has been demonstrated that morphological changes crucially depend on the composition and surface doping: doping with Mo or Mo/Rh significantly stabilizes the structure, allowing for persistence of a truncated octahedral shape during heat treatments.

Simple pyrolysis of graphene-wrapped PtNi nanoparticles supported on hierarchically N-doped porous carbon for sensitive detection of carbendazim.

A novel electrochemical sensor was established based on graphene-wrapped PtNi nanoparticles supported on three-dimensional (3D) N-doped porous carbon (G-PtNi/3D-NPC) for the highly sensitive and selective detection of carbendazim (CBZ). In this sensing system, the encapsulation of PtNi nanoparticles (NPs) by graphene can effectively prevent the aggregation tendency and enhance the structural stability. Thehierarchically porous nanostructures have a large specific surface areato expose a large number of active sites and the resultingenhancedelectrical conductivity ultimate improves the electrocatalytic activity towards CBZ. Under the optimal conditions, the prepared sensor showed excellent electrochemical responses for the determinationof CBZ with a linear range of0.5-30 μM and lower limit of detection (LOD) of 0.04 μM(S/N = 3). It also shows excellent anti-interference ability at a working potential of 0.74 V. Thefeasibility of the senor is demonstratedfor its practical assays in diluted peach and vegetable samples with acceptable recovery (95.8-97.3 %, peach; 97.2-97.6 %, vegetable) and a relative standard deviation (RSD) below 2.3%.

Synthesis of Pt–Ni Alloy Nanoparticles with Gamma Irradiation and Their Electrocatalytic Performances

Pt–Ni alloy with highly efficient and durable property might be of great significance for hydrogen evolution reaction (HER). Herein we present an efficient one-pot gamma irradiation method to prepare alloyed PtNi, PtNi3 and Pt3Ni nanoparticles with inter-crossed network structure on a large scale. The electrochemical characterization evidenced that the catalytic activity and durability of Pt3Ni were comparable with those of commercial Pt/C for HER at the current density of 10[Formula: see text][Formula: see text] in 0.5[Formula: see text]M H2SO4. We believed that the convenient and scalable gamma irradiation technique might open a way for large-scale preparation of advanced water splitting catalysts.

Bimetallic PtNi alloy modified 2D g-C3N4 nanosheets as an efficient cocatalyst for enhancing photocatalytic hydrogen evolution

Platinum-based alloy materials as effective cocatalysts in improving the performance of photocatalytic H2 production have raised great interest. Herein, a facile strategy of chemical reduction is established to synthesize bimetallic PtNi nanoparticles on 2D g-C3N4 nanosheets with excellent photocatalytic activity. The addition of PtNi nanoparticles can provide new H+ reduction sites and increase more active sites of the material. The synergistic effect between PtNi alloy nanoparticles and 2D g-C3N4 nanosheets can regulate electronic structure, narrow the band, accelerate charge transfer efficiency and inhabit the recombination of photo-induced electron (e−) and hole pairs (h+), contributing to the improvement of hydrogen evolution activity. The optimal hydrogen evolution rate of Pt0.6Ni0.4/CN shows higher hydrogen evolution rate (9528 μmol·g−1·h−1), which is 13.1 times than that of pure g-C3N4 nanosheets. Besides, a possible mechanism of photocatalytic hydrogen generation has been brought up according to a series of physical and chemical characterization. This work also provides a potential idea of developing cocatalysts integrating metal alloys with 2D g-C3N4 nanosheets for promoting photocatalytic hydrogen evolution.

Synthesis of highly efficient Nano- Ni-Pt catalyst in a rotating packed bed for cinnamaldehyde hydrogenation

Catalytic hydrogenation of α,β-unsaturated aldehydes is an efficient way to provide chemical feedstocks. Herein, Ni-Pt nanoparticles (NPs) (0.051–0.126 wt% Pt) were first synthesized by liquid reduction without surfactant in a rotating packed bed to catalyze the hydrogenation of cinnamaldehyde (CAL). Catalyst characterizations show that despite the thin amount of Pt, the regional Ni-Pt alloy and uniform distribution of Pt on Ni NPs as well as the unambiguous defect sites were found on the prepared Ni-Pt NPs. These explain the good catalytic performance of CAL hydrogenation where CAL conversion of 97.1% with hydrocinnamaldehyde (HCAL) selectivity of 88.4% was obtained. The reaction rate obtained by Ni-Pt NPs (0.0768 mol⋅g−1⋅h−1) is 2.94 times larger than that by Ni NPs (0.0261 mol⋅g−1⋅h−1) while the selectivity is not affected. Additionally, we investigated different parameters on the effect of CAL hydrogenation. Further, the kinetic study on the hydrogenation of CAL was exposed. The pre-exponential factor and activation energy are 3.22 × 1011 and 90.99 kJ/mol, respectively.

Structural Size Effect in Capped Metallic Nanoparticles

The surfactant used during a colloidal synthesis is known to control the size and shape of metallic nanoparticles. However, its influence on the nanoparticle (NP) structure is still not well understood. In this study, we show that the surfactant can significantly modify the lattice parameter of a crystalline particle. First, our electron diffraction measurements reveals that NiPt nanoparticles around 4 nm in diameter covered by a mixture of oleylamine and oleic acid (50:50) display a lattice parameter expansion around 2% when compared to the same particles without surfactant. Using high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray spectroscopy (EDX) techniques, we show that this expansion can not be explained by crystal defects, twinning, oxidation, or atoms insertion. Then, using covered NPs in the 4-22 nm size range, we show that the lattice parameter evolves linearly with the inverse of the NP size, as it is expected when a surface stress is present. Finally, the study is extended to pure nickel and pure platinum NPs, with different sizes, coated by different surfactants (oleylamine, trioctylphosphine, polyvinylpyrrolidone). The surfactants induce lattice parameter variations, whose magnitude could be related to the charge transfer between the surfactant and the particle surface.

Bifunctional nanomaterial with antibody-like and electrocatalytic activity to facilitate electrochemical biosensor of Escherichia coli

Noble metal nanoenzyme-based electrochemical biosensors has recently been used in the field of pathogenic bacteria detection. Nonetheless, the modification of bioligands on the surface of the nanoenzyme can shield its catalytic site and reduce its catalytic activity. Herein, we developed a bifunctional nanomaterial (Pt-Ni@erGO) composed of epoxy-rich graphene oxide (erGO) and platinum (Pt)-nickel (Ni) nanoparticles. erGO exhibits large specific surface area and sharp edges, which are beneficial to load high-density Pt-Ni nanoparticles and retain its catalytic activity, and insert/cut through the cell membranes. Pt-Ni@erGO displays high antibody-like activity and enhanced catalytic activity, which are conducive to the enhancement of the sensitivity. With the biosensor, we achieved the specific detection of Escherichia coli (E. coli) with a sensitivity of 38 CFU/mL and a linear range of 1.5 × 102–1.5 × 107 CFU/mL. In addition, the recovery for detecting E. coli in urine samples ranged 96.73 % to 98.85 %. Therefore, this work suggests that the designed bifunctional nanomaterial can serve as a promising electrochemical signal reporter and lead an innovative direction for the development of bifunctional probe with high antibody-like and catalytic activity.

Facile Solid-State Synthesis of Supported PtNi and PtCo Bimetallic Nanoparticles for the Oxygen Reduction Reaction

Proton-exchange membrane fuel cells (PEMFCs) represent an essential technology for the future decarbonization of the transportation sector. A major component of PEMFCs is the catalyst, often Pt-based alloys supported on carbon black, which are sufficiently active and stable upon long-term operation under the harsh reaction conditions implied by PEMFCs. However, the catalyst synthesis is typically laborious and challenging to upscale, employing organic solvents, surfactants, or uneconomical metal deposition routes. To solve this, we offer a mechanochemically assisted two-step solvent-less methodology to produce supported metal catalysts, particularly supported PtNi and PtCo catalysts. Accordingly, metal salts are first dispersed on the designated support by planetary ball milling. Subsequently, the mixture is reduced with hydrogen and annealed under an inert atmosphere to yield supported alloyed nanoparticles. Notably, by applying our procedure to the synthesis of carbon-supported PtNi and PtCo nanoparticles, we demonstrate that size, composition, and total metal loading can be finely adjusted, leading to highly performant catalysts in the oxygen reduction reaction (ORR).

Nitrogen-Doped Carbon Nanoflowers Decorated with PtNi Nanoparticles for Colorimetric Detection of Total Antioxidant Capacity

A total antioxidant capacity (TAC) assay plays an essential role in evaluating antioxidant behaviors. It mainly involves examining the dosages of antioxidants such as ascorbic acid (AA), while TAC can be measured by nanozyme with peroxidase-like activity. Herein, nitrogen-doped carbon nanoflowers decorated with uniform PtNi nanoparticles (PtNi/NCFs) were fabricated by a simple pyrolysis strategy. The obtained PtNi/NCFs showed high peroxidase-mimicking activity to catalyze 3,3′,5,5′-tetramethylbenzidine (TMB) oxidation by generating rich hydroxyl radicals (·OH) in the H2O2 system. By virtue of the PtNi/NCFs nanozyme, a visual colorimetric sensor was developed for assays of H2O2 and AA. The limits of detection were as low as 45.3 and 0.94 μM for determination of H2O2 and AA with linear ranges of 100–1000 and 1.0–20.0 μM, respectively. Moreover, such sensor was also successfully employed to detect AA and H2O2 in real tablets and juices. The PtNi/NCFs nanozyme holds great potential for practical applications.

Citral Hydrogenation over Dilute Alloy Catalysts

AbstractDilute alloy CuPt and NiPt catalysts are studied in the hydrogenation of citral, a model α,β‐unsaturated aldehyde. In situ and ex situ characterization is used to demonstrate that the Pt species within these nanoparticles are well dispersed and approach a single atom alloy structure. The distribution of Pt varies between the two host metal systems; under a hydrogen environment, the nanoparticle surface and near‐surface region of the NiPt nanoparticles is Pt rich, while the Pt is more uniformly distributed throughout the CuPt nanoparticles. When used for citral hydrogenation reactions, a rate enhancement is observed upon the addition of Pt to the Cu or Ni host catalysts, however this enhancement is determined to be due to the presence of additional metal and not a synergistic effect of the two metals. The Pt structure does, nonetheless, influence the observed selectivity trends. NiPt/SiO2 catalysts have high selectivity to the unsaturated aldehyde citronellal while the CuPt/SiO2 catalysts have increased selectivity to unsaturated alcohol products. This increased selectivity is attributed to a combination of hydrogen dissociation over Pt sites and a decrease in size of Cu ensembles due to the presence of Pt, which favors binding and hydrogenation of C=O rather than C=C bonds.

Nanostructure Engineering and Electronic Modulation of a PtNi Alloy Catalyst for Enhanced Oxygen Reduction Electrocatalysis in Zinc-Air Batteries.

PtNi nanoalloys have demonstrated electrocatalysis superior to that of benchmark Pt/C catalysts for the oxygen reduction reaction (ORR), yet the underlying mechanisms remain underexplored. Herein, a PtNi/NC catalyst comprising PtNi nanoparticles (∼5.2 nm in size) dispersed on N-doped carbon frameworks was prepared using a simple pyrolysis strategy. Benefiting from the individual components and a hierarchical structure, the PtNi/NC catalyst exhibited outstanding ORR activity and stability (E1/2 = 0.82 V vs RHE and 8 mV negative shift after 20000 cycles), outperforming a commercial 20 wt % Pt/C catalyst (E1/2 = 0.81 V and 32 mV negative shift). A prototype zinc-air battery constructed using PtNi/NC as the air electrode catalyst achieved highly enhanced electrochemical performance, outperforming a battery constructed using Pt/C as the ORR catalyst. Density functional theory calculations revealed that the improved ORR activity of the PtNi nanoalloys originated from charge redistribution with a suitable metal d-band center to promote the formation of the ORR intermediates.

Fine-tuning catalytic performance of ultrafine bimetallic nickel-platinum on metal-organic framework derived nanoporous carbon/metal oxide toward hydrous hydrazine decomposition

Heterogeneous catalysts with a high performance as well as low cost is pivotal but still challenging for hydrous hydrazine (N2H4·H2O) as a hydrogen storage material. Herein, bimetallic PtNi nanoparticles are well dispersed on nitrogen doped porous carbon/zirconia support (PtNi/NC-ZrO2). PtNi/NC-ZrO2 nanocatalysts could be responsive and completely for catalyzing hydrous hydrazine decomposition with a H2 selectivity of 100% as well as a turnover frequency of 1716 h−1 measured at 323 K, outperforming most heterogeneous metal catalysts. This is mainly attributed that bi-support NC-ZrO2 can efficiently expedite the electron transfer to metallic NPs and re-construct the electronic structure bimetallic active sites for selectively catalyzing hydrous hydrazine decomposition.

Efficient Pt-based nanostructured electrocatalysts for fuel cells: One-pot preparation, gradient structure, effect of alloying, electrochemical performance

This paper proposes an environmentally friendly one-pot synthesis approach for the PtCu and PtNi nanoparticles with the gradient structure on the carbon support. This method offers exceptional advantages over other approaches. Among them there is a surfactant-free synthesis, being low-temperature, simple, fast, and one-pot. The bimetallic electrocatalysts with a reduced platinum content for proton-exchange membrane fuel cells have been obtained. The proposed method is promising in terms of scaling and transition to commercial production. In this study, we first attempted to apply the gradient synthesis strategy to the PtNi/C catalysts in order to make this method versatile. We obtained the high-performance PtNi/C and PtCu/C catalysts, exhibiting the specific ORR activity higher than that of the commercial Pt/C catalyst by 3 and 4.6 times, respectively.

PtNi alloy nanoparticles grown in situ on nitrogen doped carbon for the efficient oxygen reduction reaction.

Currently, Pt based materials are still the most efficient oxygen reduction reaction (ORR) catalysts. However, their poor stability obstructs the commercial viability of fuel cells. To lower the reaction potential barrier and enhance the stability, we constructed alloy PtNi nanoparticles (NPs) with a Pt-rich surface supported on nitrogen-doped carbon (NC) via a simple one-step solvothermal method using easily accessible reagents. The synthesized PtNi/NC exhibits enhanced mass activity (MA), specific activity (SA), and positive onset potential compared with commercial Pt/C catalysts. Meanwhile, the half-wave potential shifted negatively to only 18 mV after 5000 cycles for PtNi/NC, indicating excellent stability. The enhanced ORR performance can be ascribed to the introduction of Ni into Pt optimizing the adsorption energy of Pt towards oxygen by adjusting the d band center of the Pt atom and stronger interaction between the metal NPs and support. Our work provides a potential synthesis strategy for developing a Pt-based catalyst with a low Pt loading and high ORR performance.

Selective dealloying of chemically disordered Pt-Ni bimetallic nanoparticles for the oxygen reduction reaction.

Changes in electronic and compositional structures of Pt-Ni electrocatalysts with 44% of Ni fraction with repeated chemical dealloying have been studied. By comparing the Pt-enriched surfaces formed using hydroquinone and sulfuric acid as a leaching agent, we found that hydroquinone generated Pt-enriched surfaces exhibit the highest oxygen reduction reaction (ORR) activity after repeating the treatment twice. In particular, it was found that while sulfuric acid causes an uncontrollable dissolution of Ni clusters, the unique selectivity of hydroquinone allows the preferential dissolution of Ni atoms alloyed with Pt. Despite its wide usage in the field, the results show that traditional acid leaching is unsuitable for Pt-Ni alloys with a high Ni content and an incomplete alloying level. We finally proved that the unique and lasting selectivity of hydroquinone enables an incompletely alloyed Pt-Ni catalyst to obtain a highly ORR active Pt shell region without an extensive loss of Ni.

Solid-phase preparation of defective carbon supported PtNi alloy electrocatalyst and analysis of its oxygen reduction mechanism

In the present work, PtNi-loaded defective carbon (Pt/ZnPPC) was prepared by solid-phase method. Carbon support with specific defect types, such as Zn metal nitrogen carbon (ZnPPC850), N-doped carbon (ZnPPC950) and defective carbon (ZnPPC1050), were selectively obtained by optimizing the pyrolysis temperature to explore the effect of defect types on oxygen reduction reactions (ORR). Electrochemical measurements showed that the half-wave potential of the PtNi metal nanoparticle-loaded ZnPPC1050 catalyst (PtNi-ZnPPC1050) outperformed the commercial JM-Pt/C by 35 mV, and by 45 mV compared to the PtNi-loaded ZnPPC950 catalyst (PtNi-ZnPPC950), suggesting that the defects in the ZnPPC1050 support resulting from the evaporation of N by pyrolysis can interact well with Pt metal electrically, allowing the PtNi nanoparticles to be uniformly distributed. Meanwhile, the defects lead to the carrier containing a large number of active sites making its catalytic performance even much better than the pyridine nitrogen sites in ZnPPC950. The carbon defect structure is loosened and porous with high specific surface area, which can effectively load PtNi nanoparticles and enhance the mass transfer. We obtained a new bimetallic oxygen reduction catalyst loaded with PtNi on defective carbon and elucidated the effect of five-membered ring carbon defect structure and N-doped structure on metal-carrier interaction.

Dehydrogenation of N2H4·H2O over NiMoO4 nanorods-stabilized NiPt bimetal nanoparticles for on-demand H2 evolution

In order to effectively and safely produce, deposit and carry H2 gas, the exploration of the“on–off”switch for demand-based H2 generation from completely N2H4·H2O dehydrogenation is a practically important matter. Herein, we first design and synthesize a battery of nickel molybdate nanorods (NMN)-stabilized NixPty bimetallic nanoparticles (NixPty/NMN), by immobilization of ultrafine NiPt nanoparticles at the surface of nickel molybdate nanorods (NMN), for the high-efficiency and selective demand-based H2 generation from completely N2H4·H2O dehydrogenation. Among them, NMN is synthesized from nickel chloride and sodium molybdate under green hydrothermal condition. Then, the optimized nano-catalyst Ni1Pt1/NMN exhibits the highest turnover frequency (TOF) of 3750 h−1 in H2 generation from N2H4·H2O dehydrogenation at 50 °C with 100 % H2 selectivity, due to its excellent synergistic effect. The comparison of other common supports, including Co3O4, Fe3O4, ZnO, ZrO2 and MoS2, has highlighted the vital role of NiMoO4 nanorods in N2H4·H2O dehydrogenation. More interestingly, the significantly selective“on–off”switch for on-demand H2 generation from N2H4·H2O dehydrogenation has been successfully developed by pH adjusting.