PtNi Bimetallic Nanoparticles Research Articles

Facile preparation of PtNi/Cs derived from the precipitation polymerization of a Poly(amic acid) for efficient hydrogen evolution reaction catalysis

Hydrogen evolution reaction (HER) of water is currently one of the most potential ‘green hydrogen’ production technology to alleviate the energy scarcity and environmental contamination. In this study, ultrafine platinum/nickel bimetallic nanoparticles loaded porous carbon nanocomposite, noted as PtNi/Cs, is facilely prepared by employing the precipitation polymerization of a poly (amic acid) (PAA), which shows superior catalytic performance toward HER. The synthesis of PAA is achieved via a stepwise polymerization of 4,6-diaminino-2-mercaptopyrimidine and pyromellitic dianhydride at room temperature, and the porous precursor is formed during the polymerization. Upon pyrolysis of the precursor in an inert atmosphere, carbon nanoaggregates with inherited porosity are fabricated. Ultrafine PtNi bimetallic nanoparticles with size of 3.3 ± 0.7 nm can be efficiently deposited, exhibiting an overpotential of 26.4 mV at 10 mA cm−2 and a mass activity of 2.92 A mgPt−1, superior than commercial Pt/C of 36.8 mV. The excellent HER performance can be attributed to the formation of ultrafine PtNi bimetallic nanoparticles and the electron transfer from PtNi to the nitrogen atoms on the carbon support.

A highly efficient and stable PtNi bimetallic nanoparticles modified on Mo2C decorated N-doped carbon flowers catalysts for the remediation of environmental pollutants

The unregulated discharge of nitroaromatics (NAs) and organic dye contaminants into aquatic ecosystems is a growing global concern, highlighting the urgent need for the development of effective wastewater treatment technology. In this study, we prepared Mo2C decorated on N- doped carbon flowers supported with PtNi bimetallic (PtxNiy@Mo2C/NCF) nanoparticles using the self-polymerization of dopamine and followed by the chemical reduction methods. These catalysts, with varying Pt:Ni ratios, were designed for the highly efficient catalytic reduction of NAs and rhodamine b (RhB) under the mild reaction conditions. The HR-TEM images confirmed the formation of spherical PtNi bimetallic NPs with an average diameter of 1.68 ± 0.6nm. The prepared PtxNiy@Mo2C/NCF catalysts exhibited significantly higher catalytic efficiency for 4-nitrophenol (4-NP) reduction compared to their respective monometallic counterparts using NaBH4. Particularly, the Pt0.75Ni0.25@Mo2C/NCF catalyst showed superior catalytic activity with the apparent rate constant (kapp: 0.6703min-1) and TOF (17.0 × 10-7molmg-1 min-1) and high recyclability over eight consecutive recycles. Furthermore, the Pt0.75Ni0.25@Mo2C/NCF catalyst also exhibited high catalytic activity for other NAs and RhB dye reduction with excellent yields. This enhanced catalytic activity of Pt0.75Ni0.25@Mo2C/NCF catalyst could be ascribed to the synergistic effect of the bimetallic systems, leading to more efficient reactions. Additional experiments were conducted on a fixed bed reactor to demonstrate that the Pt0.75Ni0.25@Mo2C/NCF catalyst effectively reduce both 4-NP and RhB dye over 15 successive runs. This work may pave the way for using PtxNiy@Mo2C/NCF catalysts in various wastewater treatment applications.

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.

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.

Bimetallic NiPt nanoparticles-enhanced catalyst supported on alginate-based biohydrogels for sustainable hydrogen production

Alginate hydrogel beads were loaded with bimetallic NiPt nanoparticles by in situ reduction of the respective polymer matrix containing precursor metallic ions using a NaBH4 aqueous solution. The alginate hydrogel beads loaded with NiPt nanoparticles were characterized by TEM, AAS, FT-IR, TGA, XPS, and oscillatory rheometry. The prepared hybrid hydrogels were proven to be effective as catalytic materials for the hydrolysis of ammonia borane (AB) for quantitative hydrogen generation using catalytic loadings of 0.1 mol%. In addition, the reaction mechanism of the hydrolytic reaction using NiPt loaded alginate hydrogel beads was determined by Langmuir-Hinshelwood model. The experimental results showed that the reaction mechanism consisted of an initial fast adsorption of reactants at the surface of the nanoparticles, followed by a rate-limiting surface reaction. The NiPt nanoalloys exhibited an enhanced behavior for hydrogen generation with a maximum TOF of 84.1 min−1, almost 71 % higher compared to monometallic platinum atoms, and likely related to a synergistic interaction between both metals. Finally, the hydrogel matrix enabled the material to be easily recovered from the reaction medium and reused in further catalytic cycles without desorption of active nanoparticles from the material.

Mn‐Modified Graphitic Carbon Nitride‐Supported Bimetallic PtNi Nanoparticles for Hydrogen Generation from Hydrous Hydrazine

AbstractMn‐modification, as a method of material element modification, has a vital efficacy on the structure of materials, providing abundant active sites for the loading of metal nanoparticles. Herein, highly dispersed PtNi nanoparticles deposited on Mn‐modified graphitic carbon nitride (g‐C3N4) was synergistically constructed by a facile and valid impregnation reduction method. Interestingly, among all the tested samples, the obtained Pt0.6Ni0.4/(MnOx)2‐C3N4 display perfect catalytic activity towards decomposition of hydrous hydrazine to produce hydrogen in alkaline solution, with the value of turnover frequency (TOF) is 2749 h−1 at 323 K. Simultaneously, the as‐synthetic catalyst remains outstanding hydrogen selectivity and stability after five recycles. This work proposes a novel strategy for structural modification catalysts to enhance the catalytic performance for dehydrogenation of hydrous hydrazine.

Dehydrogenation of hydrous hydrazine over carbon nanosphere- supported PtNi nanoparticles for on-demand H2 release

In despite of significant progresses have been accomplished in the programming and development of updated and efficient nana-catalysts for H2 production from a wide variety of chemical hydrogen storage materials. However, it is a practical matter of the utmost importance to develop the “on-off” control for on demand H2 release in the cause of effectively and safely producing, carrying and depositing H2 gas. Herein, we have first designed and synthesized a sequence of carbon nanosphere (CNS)-stabilized bimetallic PtNi nanoparticles (PtNi/CNS), by stabilization of nearly monodispersed PtNi bimetallic nanoparticles onto the surface of carbon nanosphere, for the highly selective and efficient on-demand H2 release upon the dehydrogenation of hydrous hydrazine. Then, the optional nanocatalyst Pt1Ni1/CNS exhibits the highest catalytic performance in hydrogen production from dehydrogenation of hydrous hydrazine, with 100 % H2 selectivity and the turnover frequency (TOF) of 3928 mol (H2)·molcat−1·h−1 at 50 °C. The detailed physical characterizations have confirmed that the superior catalytic performance of Pt1Ni1/CNS in the H2 release upon hydrous hydrazine dehydrogenation is attributed to the electronic interaction and synergistic effect between Ni and Pt. More importantly, the highly selective “on-off” control for demand-based H2 release upon the dehydrogenation of hydrous hydrazine is successfully realized by pH regulation.

Bimetallic Pt-Ni Nanoparticles Confined in Porous Titanium Oxide Cage for Hydrogen Generation from NaBH4 Hydrolysis.

Sodium borohydride (NaBH4), with a high theoretical hydrogen content (10.8 wt%) and safe characteristics, has been widely employed to produce hydrogen based on hydrolysis reactions. In this work, a porous titanium oxide cage (PTOC) has been synthesized by a one-step hydrothermal method using NH2-MIL-125 as the template and L-alanine as the coordination agent. Due to the evenly distributed PtNi alloy particles with more catalytically active sites, and the synergistic effect between the PTOC and PtNi alloy particles, the PtNi/PTOC catalyst presents a high hydrogen generation rate (10,164.3 mL∙min−1∙g−1) and low activation energy (28.7 kJ∙mol−1). Furthermore, the robust porous structure of PTOC effectively suppresses the agglomeration issue; thus, the PtNi/PTOC catalyst retains 87.8% of the initial catalytic activity after eight cycles. These results indicate that the PtNi/PTOC catalyst has broad applications for the hydrolysis of borohydride.

Effect of Different Carbon Supports on the Activity of PtNi Bimetallic Catalysts toward the Oxygen Reduction

To evaluate supports’ effects on catalytic activity toward the oxygen reduction reaction (ORR), a simple and controlled chemical synthesis, involving the hot injection of metal precursors, was developed to produce bimetallic PtNi nanoparticles (75 wt.% Pt and 25 wt.% Ni), supported on carbon nanotubes (CNTs) and carbon nanofibers (CNFs). The synthesized electrocatalyst was characterized using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), and scanning transmission electron microscopy (STEM). To determine the catalytic activity, an electrochemical evaluation of the synthesized catalysts in an acidic medium was performed using cyclic voltammetry (CV), CO stripping, and rotating disk electrode (RDE) tests. The presence of Pt and Ni in the nanoparticles was confirmed by EDS and XRD. Based on the STEM micrographs, the average particle size was 30 nm. Compared to the commercial Pt/C catalyst, the PtNi/CNT catalyst exhibited higher specific activity and slightly lower mass activity toward ORR in a 0.1 M HClO4 electrolyte solution.

Alkali-assisted synthesis of ultrafine NiPt nanoparticles immobilized on La2O2CO3 for highly efficient dehydrogenation of hydrous hydrazine and hydrazine borane

Designing highly active and selective metal nanocatalysts for use in liquid chemical hydrides is highly attractive but remains a critical challenge. Herein, bimetallic NiPt nanoparticles (NPs) immobilized on lanthanum oxycarbonate (NiPt/La2O2CO3) have been facilely synthesized via an alkali-assisted reduction method. The introduction of NaOH is the key factor to the formation of the well-dispersed and ultrafine NiPt NPs (2.8 nm). The obtained Ni0.6Pt0.4/La2O2CO3 exhibits an extraordinarily high catalytic activity and 100% H2 selectivity for hydrous hydrazine dehydrogenation, providing a turnover frequency value (TOF) high up to 490 h−1 at 298 K. Additionally, the NiPt/La2O2CO3 prepared with NaOH demonstrates higher catalytic performance and lower activation energy than that of NiPt/La2O2CO3_N prepared without NaOH. Moreover, the NiPt/La2O2CO3 also shows an outstanding catalytic efficiency (TOF = 1200 h−1) for dehydrogenation of hydrazine borane at 298 K. The efficient catalytic performance may be attributed to the small size effect, the strong metal-support interaction, and the NaOH promotion effect. This alkali-assisted reduction method provides a new perspective for preparing of highly efficient catalysts in clean energy application.

Supported Pt-Ni bimetallic nanoparticles catalyzed hydrodeoxygenation of dibenzofuran with high selectivity to bicyclohexane

Catalytic hydrodeoxygenation (HDO) is one of the most effective methods to upgrade the oxygen-containing compounds derived from coal tar to valuable hydrocarbons. Herein, an efficient bimetallic catalyst Pt1Ni4/MgO was prepared and applied in the HDO of dibenzofuran (DBF). High yield (95%) of the desired product bicyclohexane (BCH) was achieved at 240 °C and 1.2 MPa of H2. Superior catalytic performance could be ascribed to the “relay catalysis” of Pt sites and Ni sites, and the reaction pathway is proposed as well. Scale-up experiment and recyclability test were also performed, which demonstrated the recyclability and promising potential application of Pt1Ni4/MgO.

PtNi Bimetallic Nanoparticles on MgAlO Microflower Supports as Adsorbents for Desulfurization of Benzene

Palladium adsorbent is used in the ultradeep desulfurization process of benzene to prepare refined benzene, which is an important commercial chemical raw material in the petrochemical industry. However, with the increasing cost of palladium adsorbent, the wide application of palladium adsorbent in the benzene refining process is greatly limited. Here, we rationally designed PtNi/MgAlO adsorbent using the 3D nanomicroflower structure of MgAlO as the support and PtNi bimetallic nanoparticles as the active component. Various characterization techniques including BET, XRD, SEM, TEM, TPR, XPS, and N2-TPD were used to investigate the correlation between the adsorption performance and the microstructure of the adsorbent. The results show that the PtNi/MgAlO adsorbent exhibited an excellent adsorption sulfur capacity of 1.74 mg/g. Also, nearly 100% thiophene elimination was observed for 382 h, better than the commercial Pd/Al2O3 adsorbent. It shows great potential application in the ultradeep desulfurization of benzene.

Nitrogen-functionalized carbon nanotube-supported bimetallic PtNi nanoparticles for hydrogen generation from hydrous hydrazine.

Herein, ultrafine PtNi nanoparticles (NPs) supported on N-functionalized multi-walled carbon nanotubes (N-MWCNTs) were facilely obtained. The N species on N-MWCNTs not only benefit the formation of PtNi NPs but also accelerate the dehydrogenation of hydrous hydrazine, affording a high turnover frequency of 1595 h-1 with 100% H2 selectivity. In addition, the N species can be used as an "anchor" to stabilize the bimetallic NPs and efficiently restrain the aggregation, giving robust stability of the catalysts for decomposition of hydrous hydrazine over PtNi/N-MWCNTs.

Phase separated bi-metallic PtNi nanoparticles formed by pulsed laser dewetting

We present morphological and compositional analysis of phase-separated Pt–Ni alloy nanoparticles (NPs) formed by ns pulsed laser dewetting. The PtNi NPs obtained by the pulsed laser dewetting consist of phase-separated multiple domains including Pt3Ni, PtNi and PtNi3 phases with various crystal orientations as revealed by transmission electron microscopy, which is in contrast to thermal dewetting resulting NPs of a uniform composition. A three-dimensional (3D) electron density map of a dewetted PtNi NP obtained using the coherent x-ray diffraction microscopy elucidates the 3D morphology of Pt- and Ni-rich regions together with a nano-cavity formed during the pulsed laser irradiation.

PtNi Nanoparticles Loading on Sandwich-Like Hybrid Nanocarbon Support for Methanol Oxidation

A novel electrocatalyst, PtNi-graphene/carbon dots/graphene (PtNi/GCG), for methanol oxidation was prepared onto the glassy carbon electrode (GCE). The GCG hybrid nanocarbon support with sandwich-structure was dried onto GCE surface. Then, PtNi bimetallic nanoparticles were modified loaded on the GCG hybrid nanocarbon support via electrodeposition to obtain PtNi/GCG electrocatalyst. The as-prepared PtNi/GCG electrocatalyst was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and electrochemical analysis. The structure of PtNi/GCG shows that the PtNi nanoparticles were dispersed between the layered graphene. From electrochemical analysis, compared with Pt and PtNi/graphene catalysts, the as-prepared PtNi/GCG in this work has much better electrocatalytic properities towards methanol oxidation and shows better stability. The sandwich-structured electrocatalyst showed improved performance towards the methanol oxidation. The reason can be attributed to the synergistic effect between metals and the introduction of carbon dots between graphene layers. What’s more, carbon dots loading onto graphene layers effectively, which not only can increase the electrical conductivity, make available more active sites and reactive surface area, but also can enhance the dispersion of PtNi nanoparticles in the composite catalyst.

PtNi bimetallic structure supported on UiO-67 metal-organic framework (MOF) during CO oxidation

Supported bimetallic nanoparticles (BNPs) are promising catalysts, but study on their compositional and structural changes under reaction conditions remains a challenge. In this work, the structure of PtNi BNPs supported on UiO-67 metal–organic framework (MOF) catalyst (i.e., PtNi@UiO-67) was investigated by in situ by near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS). The results showed differences in the reduction behaviour of Ni species in PtNi BNPs and monometallic Ni supported on UiO-67 catalysts (i.e., PtNi@UiO-67 and Ni@UiO-67), suggesting charge transfer between metallic Pt and Ni oxides in PtNi@UiO-67. Under CO oxidation conditions, Ni oxides segregated to the outer surface of the BNPs forming a thin layer of NiOx on top of the metallic Pt (i.e., a NiOx-on-Pt structure). This resulted in a core-shell structure which was confirmed by high-resolution scanning transmission electron microscopy (HR-STEM). Accordingly, the layer of NiOx on PtNi BNPs, which is stabilised by charge transfer from metallic Pt, was proposed as the possible active phase for CO oxidation, being responsible for the enhanced catalytic activity observed in the bimetallic PtNi@UiO-67 catalyst.

Effects of carbon supporter on oxygen reduction reaction catalytic activity in proton exchange membrane fuel cell of bimetallic Pt-Ni nanoparticles electrocatalysts

Platinum nanoparticles supported on carbon black (Pt/C) are widely used as the electrocatalysts for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). Nevertheless, the kinetics of the ORR or rate of reaction is relatively slow. Recently, researchers theoretically report that, the bimetallic platinum-nickel supported on carbon black (Pt-Ni/C) have extremely high ORR activities. Therefore, this work aims to synthesize Pt-Ni/C nanoparticles electrocatalysts for ORR via solid-state chemistry method (gas phase synthesis), which involved impregnation of metal precursors on supported carbon and reducing them in an environment of carbon monoxide (CO) and hydrogen (H2) gases mixture. The Pt-Ni nanoparticles were prepared with different carbon (i.e. Graphene, Vulcan XC-72R and Ketjen black). The ORR activities and durability of these electrocatalysts were examined by voltammetry technique, which consisted of cyclic voltammetry (CV) and linear sweep voltammetry (LSV) under acidic condition. The results demonstrated that different types of carbon supporters could affect the ORR catalytic activities. Pt-Ni nanoparticles supported on ketjen black (Pt-Ni/K) had the highest ORR activities for both specific activity (SA) and mass activity (MA). Furthermore, after 4,000 voltage cycles of the accelerated durability test (ADT), the Pt-Ni/Ketjen black still showed better ORR stability than Pt-Ni/Vulcan XC-72R and Pt-Ni/Graphene, respectively.

Ultrafine Bimetallic Pt–Ni Nanoparticles Achieved by Metal–Organic Framework Templated Zirconia/Porous Carbon/Reduced Graphene Oxide: Remarkable Catalytic Activity in Dehydrogenation of Hydrous Hydrazine

AbstractEmerging as a promising hydrogen carrier, hydrous hydrazine has attracted great attention in hydrogen storage and transportation. Herein, by using a wet‐chemical reduction method, ultrafine bimetallic PtNi nanoparticles (NPs) with an average size of 1.8 nm are immobilized on a metal–organic framework templated zirconia/porous carbon/reduced graphene oxide (ZrO2/C/rGO) support. Monometallic Pt and Ni NPs show no activities for the catalytic dehydrogenation of hydrous hydrazine. Surprisingly, the obtained bimetallic Pt–Ni NPs exhibits a significantly enhanced catalytic activity toward the hydrogen generation from hydrous hydrazine, with which an extremely high turnover frequency value can be afforded to 1920 h−1 at 323 K. The highly enhanced catalytic activity can be attributed to the small size effect, the strong synergistic effect between Pt and Ni atoms as well as the strong metal‐support interactions. The present work provides a new insight to developing high‐performance bimetallic catalysts for advanced catalytic and energy technologies.

PtNi nanoparticles supported on electrochemically reduced porous graphene oxide for methanol oxidation reaction

Various types of fuel cells as clean and portable power sources show a great attraction, especially direct methanol fuel cells (DMFCs) having high energy density and convenient fuel storage. In this paper, PtNi bimetallic nanoparticles (NPs) supported on the electrochemically reduced porous graphene oxide (ERPGO) was fabricated by one-step electrochemical reduction of the mixture of H2PtCl6, NiSO4 and porous graphene oxide (PGO). The obtained hybrid of PtNi/ERPGO was investigated by using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS). Furthermore, the electrocatalytic activity for methanol oxidation reaction (MOR) was evaluated by electrochemical method. The experimental results have demonstrated that PtNi/ERPGO enhanced electrocatalytic activity, which might be attributed to the bifunctional mechanism and the existence of unique pore structure on the surface of graphene sheets.

Facile and Large‐Scale Fabrication of Sub‐3 nm PtNi Nanoparticles Supported on Porous Carbon Sheet: A Bifunctional Material for the Hydrogen Evolution Reaction and Hydrogenation

Facile and large-scale preparation of materials with uniform distributions of ultrafine particles for catalysis is a challenging task, and it is even more difficult to obtain catalysts that excel in both the hydrogen evolution reaction (HER) and hydrogenation, which are the corresponding merging and splitting procedures of hydrogen, respectively. Herein, the fabrication of ultrafine bimetallic PtNi nanoparticles embedded in carbon nanosheets (CNS) by means of in situ self-polymerization and annealing is reported. This bifunctional catalyst shows excellent performance in the hydrogen evolution reaction (HER) and the hydrogenation of p-nitrophenol. Remarkably PtNi bimetallic catalyst with low metal loading (PtNi2 @CNS-600, 0.074 wt % Pt) exhibited outstanding HER activity with an overpotential as low as 68 mV at a current density of 10 mA cm-2 with a platinum loading of only 0.612 μgPt cm-2 and Tafel slope of 35.27 mV dec-1 in a 0.5 m aqueous solution of H2 SO4 , which is comparable to that of the 20 % Pt/C catalyst (31 mV dec-1 ). Moreover, it also shows superior long-term electrochemical durability for at least 30 h with negligible degradation compared with 20 % Pt/C. In addition, the material with increased loading (mPtNi2 @CNS-600, 2.88 % Pt) showed robust catalytic activity for hydrogenation of p-nitrophenol at ambient pressure and temperature. The catalytic activity towards hydrogen splitting is a circumstantial evidence that agrees with the Volmer-Tafel reaction path in the HER.