PtCo Bimetallic Nanoparticles Research Articles

Optimized Pt-Co Alloy Nanoparticles for Reverse Water-Gas Shift Activation of CO2.

Different Co contents were used to tune bimetallic Pt-Co nanoparticles with a diameter of 8 nm, resulting in Pt:Co ratios of 3.54, 1.51, and 0.96. These nanoparticles were then applied to the MCF-17 mesoporous silica support. The synthesized materials were characterized with HR-TEM, HAADF-TEM, EDX, XRD, BET, ICP-MS, in situ DRIFTS, and quasi in situ XPS techniques. The catalysts were tested in a thermally induced reverse water-gas shift reaction (CO2:H2 = 1:4) at atmospheric pressure in the 200-700 °C temperature range. All bimetallic Pt-Co particles outperformed the pure Pt benchmark catalyst. The nanoparticles with a Pt:Co ratio of 1.51 exhibited 2.6 times higher activity and increased CO selectivity by 4% at 500 °C. Experiments proved that the electron accumulation and alloying effect on the Pt-Co particles are stronger with higher Co ratios. The production of CO followed the formate reaction pathway on all catalysts due to the face-centered-cubic structure, which is similar to the Pt benchmark. It is concluded that the enhanced properties of Co culminate at a Pt:Co ratio of 1.51 because decreasing the ratio to 0.96 results in lower activity despite having more Co atoms available for the electronic interaction, resulting in the lack of electron-rich Pt sites.

Dealuminated Beta stabilized bimetallic PtCo nanoparticles for oxidative dehydrogenation of propane with CO2

Oxidative dehydrogenation of propane in the presence of carbon dioxide (CO2) effectively promotes the utilization of alkanes and CO2 to produce high value-added olefins and carbon monoxide products. In this work, bimetallic PtCo nanoparticles with diameter of 1–2.5 nm loaded on dealuminated nano-Beta zeolite were successfully prepared for propane oxidative dehydrogenation with CO2. The silanol groups formed after dealuminization of nano-Beta zeolite acted as the anchoring sites to enhance the dispersion of PtCo nanoparticles, and the introduction of Co further promoted the uniform distribution of Pt, resulting in smaller bimetallic PtCo nanoparticles. By optimizing the Pt/Co ratio, the conversion of propane and CO2 at 550 °C was as high as 51.8 % and 30.6 %, respectively. The dealuminized Beta supported PtCo nanoparticles exhibited high stability during the reaction, and there was no obvious aggregation of PtCo nanoparticles after 6 h on stream. In this study, the highly efficient catalyst prepared by impregnation method using modified commercial zeolite as the carrier is suitable for large-scale production and shows great practical prospect in the application of propane oxidative dehydrogenation with CO2.

Nanozyme colorimetric sensing of L-cysteine and copper ions based on PtCo nanoparticles@multi-walled carbon nanotubes.

In this work, PtCo bimetallic nanoparticles supported on multi-walled carbon nanotubes (PtCo@MWCNTs) nanohybrid was prepared simply and used for the first time as a novel nanozyme in the colorimetric sensing of L-cysteine (L-Cys) and Cu2+. Due to its strong enzyme-like catalytic activity, the prepared PtCo@MWCNTs nanohybrid can catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to form ox-TMB without H2O2. Interestingly, the oxidase-like active of PtCo@MWCNTs was effectively suppressed by L-Cys, which could reduce ox-TMB to colorless TMB and lead to a pronounced blue fading, and the absorbance at 652nm gradually decreased with increasing L-Cys concentration. On the other hand, the nanozyme activity of PtCo@MWCNTs can be recovered due to the complexation between L-Cys and Cu2+. Therefore, a colorimetric method based on PtCo@MWCNTs nanozyme was established to detect L-Cys and Cu2+. The results show that the assay platform has simple, rapid, sensitive performance and good selectivity. The detection limits for L-Cys and Cu2+ are 0.041μM and 0.056μM, respectively, coupled with the linearities of 0.01 ~ 60.0μM and 0.05 ~ 80.0μM. The successful first application of PtCo bimetal-based nanozyme in colorimetric sensing herein opens a new direction for nanozyme and colorimetric analysis, showing great potential applications.

Electron synergy effect in the PtCo/CNTs bimetallic catalysts for promoting highly selective and stable hydrogenation of crotonaldehyde

Herein, we synthesized PtCo/CNTs, Pt/CNTs, and Co/CNTs nanocatalysts at room temperature by chemical reduction method. The synergistic effect in PtCo/CNTs for crotonaldehyde (CAL) hydrogenation is investigated. The nanostructures, morphologies, electronic property, Pt–Co interaction, surface characteristic and composition of the catalysts are examined by XRD, BET, SEM, XPS, HRTEM, STEM, STEM-EDX elemental maps and line profiles and H2-TPD. It is found that Pt and Co forms PtCo bimetallic nanoparticles in the PtCo/CNTs catalyst and the PtCo bimetallic nanoparticles are coated on multi-walled carbon nanotubes. And PtCo/CNTs achieves 83.5% CAL conversion, 91.3% crotyl alcohol (COL) selectivity, and 647.4 h−1 turnover frequency (TOF) at 60 °C within 2 h under 3 MPa hydrogen, and its catalytic performance remains basically unchanged after five recycles. According to the analysis, the presence of PtCo bimetallic particles lead to electron transferring from Co to Pt (synergy effect), which improves their activation ability of hydrogen and desorption of CC in COL and thus enhances its selectivity to COL.

Ethylene glycol-assisted synthesis of reduced graphene oxide-supported bimetallic Pt-Co nanoparticles for the ultra-sensitive detection of tert-butyl hydroquinone

Ethylene glycol-assisted synthesis of reduced graphene oxide-supported bimetallic Pt-Co nanoparticles for the ultra-sensitive detection of tert-butyl hydroquinone

Highly selective PtCo bimetallic nanoparticles on silica for continuous production of hydrogen from aqueous phase reforming of xylose

Hydrogen (H2) is a promising energy vector for mitigating greenhouse gas emissions. Lignocellulosic biomass waste has been introduced as one of the abundant and carbon-neutral H2 sources. Among those, xylose with its short carbon chain has emerged attractive, where H2 can be catalytically released in an aqueous reactor. In this study, a composite catalyst system consisting of silica (SiO2)-supported platinum (Pt)-cobalt (Co) bimetallic nanoparticles was developed for aqueous phase reforming of xylose conducted at 225 °C and 29.3 bar. The PtCo/SiO2 catalyst showed a significantly higher H2 production rate and selectivity than that of Pt/SiO2, whereas Co/SiO2 shows no activity in H2 production. The highest selectivity for useful liquid byproducts was obtained with PtCo/SiO2. Moreover, CO2 emissions throughout the reaction were reduced compared to those of monometallic Pt/SiO2. The PtCo bimetallic nanocatalyst offers an inexpensive, sustainable, and durable solution with high chemical selectivity for scalable reforming of hard-to-ferment pentose sugars.

Hierarchical Co3O4/SAPO-34 supported PtCo bimetallic nanoparticles as highly efficient catalyst for hydrogen generation from ammonia borane hydrolysis

Hierarchical Co3O4/SAPO-34 supported PtCo bimetallic nanoparticles (NPs) with uniform dispersion and narrow size-distribution were prepared for the hydrolysis of AB to produce hydrogen. Strategies including the sequential impregnation of cobalt and platinum precursors followed by partial reduction were employed to anchor Pt NPs. Befitting from the interfacial interaction between Co and Co3O4 NPs, the intermetallic synergistic effect of PtCo NPs and the synergistic interaction between Co NPs and SAPO-34 zeolite, the prepared Pt@Co/Co3O4/SP-10(400,2) catalyst exhibited outstanding catalytic activity with a high turnover frequency (TOF) value of 314 molH2(molPt·min)-1 at 303 K. In addition, the flake-assemble hierarchical structure of SAPO-34 played an important role in improving the dispersion of metal NPs and the mass transfer rate between reactants and active sites.

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).

Synthesis and applications of highly stable silane modified reduced graphene oxide supported cobalt based platinum nanoparticle for anodic part of direct methanol fuel cells

In this study, the effects of silane on bimetallic nanoparticles modified with reduced graphene oxide were investigated for direct methanol fuel cells. In this direction, PtCo bimetallic nanoparticles were produced using the chemical reduction method. PtCo@NH2-rGO catalyst was obtained by combining these nanoparticles on 3-Aminopropyltriethoxysilane (APTES) modified reduced Graphene Oxide (rGO). Characterization of the PtCo@NH2-rGO catalyst was performed by X-Ray Diffractometry (XRD), Fourier Transform Infrared (FTIR), and UV–Visible Spectrophotometer (UV-VIS). The methanol oxidation performances of the obtained catalysts were investigated in order to observe the electrochemical effect of NH2-rGO supporting agent on unsupported PtCo and supported PtCo (PtCo@NH2-rGO) catalysts. The PtCo@NH2-rGO electrocatalyst showed a high oxidation peak current density (86.02 mA/cm2) for the anodic portion of the direct methanol fuel cell. This result shows the high performance of the NH2-rGO supported catalyst for direct methanol fuel cells. The resulting catalyst gives promise for potential direct fuel cell applications.

Enhanced electrochemical hydrogen storage performance upon the Pt-Co nanoparticles decorated N-doped mesoporous carbon

Carbonaceous materials are proved to be the promising materials for storing hydrogen electrochemically. To enhance the performance, decorated Pt-Co bi-metallic nanoparticles onto the N-doped mesoporous carbon material were developed while Co enriched the capacity, and Pt was used to enhance the kinetic performance. Results showed that the hydrogen storage capacity of 2% Pt-Co@NMC material was over 360 mAh g−1 under a current density of 100 mA g−1, and the capacity retention was 53.6% under the 2000 mA g−1 rate over that at 100 mA g−1. Furthermore, it also carries low self-discharge and good cycling performance. First-principles calculations revealed that the adsorption of the H atom on the Pt (110) crystal plane is the most stable, which is mainly due to the hydrogen spillover effect to improve the kinetic performance of hydrogen intercalation.

Tuning the catalytic performance of Pt/SiO2 catalysts by CoOx modification for selective hydrogenations of unsaturated carbonyl compounds

Tailoring the interface between active metals and promoters to improve catalytic performance is a challenging issue for bicomponent catalysts. Herein, we developed a series of silica supported Pt-CoOx hybrid nanocatalysts though in situ oxidation of supported bimetallic PtCo nanoparticles (NPs) with different Pt/Co ratios. Focusing on the hydrogenation of acetophenone to 1-phenylethanol as the model reaction, the obtained Pt-CoOx/SiO2 catalysts showed superior activity and selectivity compared to Pt/SiO2, and the sample with a Co/Pt molar ratio of 1/3 performed the best. Our research showed that the CoOx on Pt not only changed its electronic and geometric properties, but also promoted the adsorption of reactants and the dissociation of H2. A further increase of the Co/Pt ratio to 1/1, however, reduced the activity due to blockage of the Pt surface.

Tuning surface composition of multiwalled carbon nanotubes supported Pt-Co bimetallic nanoparticles for boosting methanol oxidation catalysis

Developing catalysts with high performance and low cost for methanol oxidation reaction (MOR) is the key to promoting the industrialization of direct methanol fuel cells (DMFCs). In this work, multiwalled carbon nanotubes (MWCNTs) supported PtCo alloys catalysts with improved MOR properties and anti-CO poisoning ability are successfully prepared by integrating low temperature adsorption and high temperature reduction method. The Pt1Co3@NC/MWCNTs sample with moderate Co2+ feeding content (0.81 mA/ugPt) achieves a factor of 1.93 enhancement in MOR mass activity compared to the commercial Pt/C catalyst (0.42 mA/ugPt). In addition, the Pt1Co3@NC/MWCNTs sample displays a lower CO oxidation onset potential respect to pristine Pt/C catalyst (0.74 V vs. 0.82 V). Scuh improvement of MOR activity, durability and anti-CO poisoning ability of the Pt1Co3@NC/MWCNTs catalyst is ascribed to the moderate surface compositions, optimal electronic interaction between PtCo alloys and MWCNTs, and the protection of N-doped carbon (NC) shells. This study provides a new direction to decrease the utilization of platinum and improve the MOR activity, stability and anti-CO poisoning ability of electrocatalysts which will be potential in design and fabrication of the highly efficient electrocatalysts for DMFCs applications.

Pt-Co nanoparticles supported on hollow multi-shelled CeO2 as a catalyst for highly efficient toluene oxidation: Morphology control and the role of bimetal synergism

A series of hollow multi-shelled CeO2 (HoMS-CeO2) support materials with tunable shell numbers were fabricated and applied to the catalytic oxidation of toluene. HoMS-CeO2 possess much higher catalytic activity (T90 = 236 ℃) than hollow CeO2 with only a single shell (h-CeO2) (T90 = 275℃). The porous multiple-shelled structure has a higher SBET, which strongly promotes gas distribution and provides more active sites. The superiority of this kind of structure was also verified by comparing h-Co3O4 and HoMS-Co3O4. Furthermore, Pt-Co bimetallic nanoparticles were loaded onto HoMS-CeO2. The synergistic effect between Pt and Co was verified by XPS and O2-TPD, which was observed to allow electron transfer between Pt and Co and thus regulate the electronic state of the Pt. Compared with Pt alone, Pt-Co bimetallic nanoparticles could stronglypromotethe activation of O2and oxygen mobility, as revealed by a much higher Oads content and a lower oxygen desorption temperature. Of the catalysts prepared in this study, the 1 wt% PtCo3/CeO2 catalyst was found to be the most suitable for toluene oxidation owing to its excellent activity (T90 = 158 ℃), long-term stability, and water resistance. Finally, in situ DRIFTS was employed to investigate mechanism during toluene oxidation and the possible reaction pathway was proposed.

An Enhanced‐Activity and High‐Stability PtCo/N‐Doped Carbon Skeleton Electrocatalyst Derived from UA‐ZIF‐67 Template for Methanol Oxidation

AbstractTo improve electrocatalytic performances of Pt‐based catalysts toward methanol oxidation reaction (MOR) and reduce the consumption of Pt, we report a novel strategy for preparing a PtCo/NCS catalyst with bimetallic PtCo nanoparticles supported on the nitrogen‐doped carbon skeleton (NCS) derived from ulmic‐acid ‐based ZIF‐67 (UA‐ZIF‐67) template. The synthesized optimal NCS has rich mesoporous structure with a BET specific surface area of 451 m2 g−1and average pore diameterof 4.5 nm, possesses graphitic structure containing some CNTs and many graphene layers, and is doped by 8.16 at% nitrogen in the form of pyridine N and pyrrole N. In the optimum PtCo/NCS, metallic Pt and Co nanoparticles with an average size of 3.0±0.5 nm are uniformly supported on the NCS. This PtCo/NCS catalyst shows a high electrocatalytic activity and stability for MOR due to its high electrochemically active specific surface area (ECSA) value, current density, steady‐state current and current retention. The results are attributed to small highly‐dispersed PtCo nanoparticles with good synergistic effects of bimetallic active components supported on the NCS possessing CNTs and graphene layers, suitable nitrogen doping and well‐matched hierarchical pore structure.These findings will provide a new insight in designing and synthesizing high‐performance electrocatalysts.

Carbon nanospheres supported bimetallic Pt-Co as an efficient catalyst for NaBH4 hydrolysis

Sodium borohydride (NaBH4) is widely identified as a promising hydrogen storage material, therefore, developing a catalyst with high efficiency for hydrogen production is an important subject for development and utilization of hydrogen energy. Meanwhile the hydrolytic mechanism of NaBH4 needs further study which is helpful for hydrolysis researches. In this study, an efficient catalyst comprising of carbon nanospheres (CNSs) supporting ultrafine bimetallic Pt-Co nanoparticles (CNSs@Pt0.1Co0.9) has been successfully synthesized for hydrogen evolution from NaBH4 hydrolysis. The growth of the Pt-Co nanoparticles on the surface of CNSs is regulated by adjustment of solvent during the preparation. The as-prepared CNSs@Pt0.1Co0.9 catalyst exhibits an outstanding performance in the kinetic and thermodynamic tests with the highest hydrogen generation rate (HGR) of 8943 mLH2·min−1·gM–1, initial turnover frequency (TOF) value of 280.1 moLH2·min−1·molPt–1, and a low activation energy (Ea) of 38.0 kJ·mol−1. The hydrolytic mechanism has been surveyed simultaneously by the isotopic tracer method through the mass spectrometric analysis. The catalyst retains extremely high catalytic activity value and the hydrogen generation conversion is still 100% even after five cycles in the catalytic performance tests.

GPU-based DPSO algorithm for structural optimization of Pt-Co bimetallic nanoparticles

Alloy nanoparticles (NPs) are potential candidates for catalysts in fuel cells applications, and their physical properties are associated with the corresponding stable structures. In this work, a GPU-based discrete particle swarm optimization (DPSO) method is designed to investigate the stable structure of Pt-Co alloy NPs. Register and an optimal block design are used to further increase the acceleration ratio. Comparative experiments on CPU and GPU show that the GPU-based DPSO algorithm possesses superior computational performance, and Register has a great influence on the acceleration ratio. Analyses on the stable structures of Pt-Co NPs demonstrate that Co atoms preferentially locate at vertex and edges of surface, yet Pt atoms exhibit a strong surface and sub-surface segregation only for their composition over 65%.

Competitive adsorption on PtCo/CoBOx catalysts enables the selective hydrogen-reductive-imination of nitroarenes with aldehydes into imines

Catalytic synthesis of imines from one-pot cascade hydrogen reductive imination of nitroarenes with aldehydes represents a facile, green and valuable process; however, such an economical process suffers from the poor chemoselectivity due to competitive hydrogenation of aldehydes and over-hydrogenation of imines into N-alkylated amines. Herein, bimetallic PtCo nanoparticles anchored on cobalt borate nanosheets (PtCo/CoBOx) can facilitate the unparalleled activity and selectivity towards imines through the same imination. The high chemoselectivity of imines is resulted from the competitive adsorption of reactants and products on PtCo/CoBOx, including (1) weakened adsorption of imines and its uncompetitive adsorption with aromatic amines (from nitroarenes) on bimetallic PtCo to minimize its over-hydrogenation; (2) competitive adsorption of nitroarenes on PtCo and preferential adsorption of aldehydes/nitroarenes on hydroxyl-enriched CoBOx through hydrogen bond formation to suppress hydrogenation of both aldehydes and imines; and (3) kinetically and competitively preferred reduction of nitroarenes over aldehydes to avoid hydrogenation of aldehydes.

PtCo bimetallic nanoparticles encapsulated in N-doped carbon nanorod arrays for efficient electrocatalysis

Highly-active and durable electrocatalysts are highly important for electrochemical energy conversion devices. Herein, we report the design and fabrication of PtCo bimetallic nanoparticles encapsulated in N-doped carbon nanorod arrays (PtCo@NC) on carbon cloth as an integrated binder-free catalyst for both methanol oxidation reaction (MOR) and hydrogen evolution reaction (HER). The unique structural advantage and bimetallic synergetic effect of such composite catalyst provide a high specific surface area and abundant electrochemical active sites for the electrocatalysis process. As a result, the as-obtained PtCo@NC with optimized Pt loading exhibit significantly improved methanol electro-oxidation performance in terms of high areal activity of 2.17 mA cm−2, superior CO tolerance and reliable stability in contrast to that of commercial Pt/C catalysts. In addition, the PtCo@NC catalyst also shows promising electrocatalytic activity with small onset potential of 12 mV vs RHE, low Tafel slope of 48 mV dec−1 as well as excellent long-term stability for HER.

PtCo/rGO nano-anode catalyst: enhanced power density with reduced methanol crossover in direct methanol fuel cell

The higher methanol utilization efficiency in direct methanol fuel cell (DMFC) is one of the key factors that determine the performance of DMFC. Herein, we have synthesized bimetallic PtCo nano-particles (with optimized Pt:Co ratio) decorated reduced graphene oxide (rGO) nano-composite as anode catalyst. The electrochemical response of optimized PtCo (1:9)/rGO catalyst revealed efficient oxidation of 5 M methanol in half-cell configuration with ~ 60% Faradaic efficiency. A current density of 463.5 mA/cm2 and a power density of 136.8 mW/cm2 were achieved using PtCo (1:9)/rGO anode catalyst in a complete DMFC set-up at 100 °C with 5 M methanol supply which is ~ three times greater as compared to commercial Pt/C (48.03 mW/cm2). The low activation energy of 9.88 kJ/mol indicates the faster methanol oxidation reduction (MOR) kinetics of PtCo (1:9)/rGO anode catalyst. Furthermore, the higher methanol utilization and open-circuit voltage in complete DMFC using PtCo (1:9)/rGO as compared to commercial Pt/C indicate the reduced methanol crossover. The excellent catalytic behavior of PtCo (1:9)/rGO towards MOR and high methanol utilization warrant its potential application as anode catalyst in DMFC.

Boosting hot electron flux and catalytic activity at metal\u2013oxide interfaces of PtCo bimetallic nanoparticles

Despite numerous studies, the origin of the enhanced catalytic performance of bimetallic nanoparticles (NPs) remains elusive because of the ever-changing surface structures, compositions, and oxidation states of NPs under reaction conditions. An effective strategy for obtaining critical clues for the phenomenon is real-time quantitative detection of hot electrons induced by a chemical reaction on the catalysts. Here, we investigate hot electrons excited on PtCo bimetallic NPs during H2 oxidation by measuring the chemicurrent on a catalytic nanodiode while changing the Pt composition of the NPs. We reveal that the presence of a CoO/Pt interface enables efficient transport of electrons and higher catalytic activity for PtCo NPs. These results are consistent with theoretical calculations suggesting that lower activation energy and higher exothermicity are required for the reaction at the CoO/Pt interface.