Highly efficient,large surface area and spherically shaped Pt particles deposited electrolytically synthesized graphene for methanol oxidation with impedance spectroscopy

Graphene was synthesized via electrochemical exfoliation technique of graphite rod in Poly (sodium 4-styrenesulfonate) solution. Laser Raman and X-ray Diffraction Spectroscopies were used to confirm the defects and crystal nature of graphene. The surface wettability studies based on water contact angle, further differentiates the affinity of as-prepared graphene and pristine graphite towards water. Modified Glassy carbon (GC) electrodes were prepared by electro-deposition of Platinum (Pt) on bare and graphene coated GC, denoted as GC/Pt and graphene/Pt modified GC respectively. The morphology and chemical composition of the thus synthesized graphene and graphene/Pt modified electrodes were investigated by High resolution transmission electron microscopy, Scanning electron microscopy and Energy dispersive spectroscopy. The electrochemically active surface area of the electro-deposited spherically shaped Pt particles was calculated to be 63.96 m² g^?1 and 25.10 m² g^?1 on graphene/Pt and GC/Pt, respectively. The electro-catalytic performance of modified electrodes for methanol oxidation was envisaged by cyclic voltammetry, linear sweep voltammetry and chronoamperometry. Graphene/Pt modified GC electrode showed higher oxidation peak current (42.90 mA cm^?2) than GC/Pt modified electrode (16.24 mA cm^?2) in forward scan of methanol oxidation because of the uniform distribution of spherically shaped Pt particles on graphene. The reaction path for methanol oxidation at different potentials was elucidated by means of Electrochemical Impedance Spectroscopy.     

Pt nanoparticles modified Au dendritic nanostructures: Facile synthesis and enhanced electrocatalytic performance for methanol oxidation

A facile and simple method is presented for the synthesis of bimetallic composites, Pt nanoparticles modified dendritic Au nanostructures (PtNPs/DGNs), in which dendritic Au was deposited on a glassy carbon electrode via a potentiostatic method and sphere-like Pt nanoparticles were decorated on Au substrates through a chemical reduction reaction. The compositions, morphologies, and structures of the PtNPs/DGNs were characterized by X-ray photoelectron spectroscopy, field emission scanning electron microscopy, and energy dispersive X-ray spectroscopy. Results indicated that bimetallic composites were successfully synthesized and spherical Pt nanoparticles were dispersed evenly on dendritic Au substrates. The number of Pt nanoparticles on Au surface was regulated by controlling the chemical reduction deposition time, allowing the electrocatalytic properties of the composite towards methanol oxidation to be tuned. Electrochemical measurements, including cyclic voltammetry and chronoamperometry, were performed to investigate the electrochemical properties and electrocatalytic behaviors of the PtNPs/DGNs towards methanol oxidation. Pt nanoparticles partially covered dendritic Au exhibited dramatically enhanced electrocatalytic activity (3.947 mA cm^?2), which was 2.65 times that of commercial carbon-supported Pt nanoparticles (1.487 mA cm^?2), along with much improved poisoning tolerance (current decline: 70.85% vs 99.36%). These enhanced performances were likely caused by the large active electrochemical area of the bimetallic nanocomposites and the change in the electronic structure of Pt when the Au surface was modified with fewer Pt nanoparticles.     

Nitrogen doped mesoporous carbon supported Pt electrocatalyst for oxygen reduction reaction in proton exchange membrane fuel cells

Nitrogen doped mesoporous carbons are employed as supports for efficient electrocatalysts for oxygen reduction reaction. Heteroatom doped carbons favour the adsorption and reduction of molecular oxygen on Pt sites. In the present work, nitrogen doped mesoporous carbons (NMCs) with variable nitrogen content were synthesized via colloidal silica assisted sol-gel process with Ludox-AS40 (40 wt% SiO₂) as hard template using melamine and phenol as nitrogen and carbon precursors, respectively. The NMC were used as supports to prepare Pt/NMC electrocatalysts. The physicochemical properties of these materials were studied by SEM, TEM, XRD, BET, TGA, Raman, XPS and FTIR. The surface areas of 11 wt% (NMC-1) and 6 wt% (NMC-2) nitrogen doped mesoporous carbons are 609 m² g^?1 and 736 m² g^?1, respectively. The estimated electrochemical surface areas for Pt/NMC-1 and Pt/NMC-2 are 73 m² g^?1 and 59 m² g^?1, respectively. It is found that Pt/NMC-1 has higher ORR activity with higher limiting current and 44 mV positive onset potential shift compared to Pt/NMC-2. Further, the fuel cell assembled with Pt/NMC-1 as cathode catalyst delivered 1.8 times higher power density than Pt/NMC-2. It is proposed that higher nitrogen content and large pyridinic nitrogen sites present in NMC-1 support are responsible for higher ORR activity of Pt/NMC-1 and high power density of the fuel cell using Pt/NMC-1 cathode electrocatalyst. The carbon support material with high pyridinic content promotes the Pt dispersion with particle size less than 2 nm.     

Facile synthesis of flower-like Au@AuPd nanocrystals with highly electrocatalytic activity for formic acid oxidation and hydrogen evolution reactions

Herein, a one-pot co-reduction method was developed to prepare flower-like Au@AuPd core-shell nanocrystals (Au@AuPd NCs) under the guidance of 2,4-diamino-6-hydroxypyrimidine (DAHP). The product was mainly characterized by microscopic measurements, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis, and its formation mechanism was discussed in details. The architectures showed much larger electrochemical active surface area (62.68 m² g^?1_Pd) than commercial Pd black (8.23 m² g^?1_Pd), together with the higher mass activity (1250 mA mg^?1) for formic acid oxidation reaction (FAOR). Besides, the catalyst displayed improved catalytic features for hydrogen evolution reaction (HER) relative to Pd black and Pt/C catalysts. These indicate the potential applications of the catalyst in energy storage and transformation.     

Effective factors improving catalyst layers of PEM fuel cell

Cathode catalyst layer has an important role on water management across the membrane electrode assembly (MEA). Effect of Pt percentage in commercial catalyst and Pt loading from the viewpoint of activity and water management on performance was investigated. Physical and electrochemical characteristics of conventional and hydrophobic catalyst layers were compared. Performance results revealed that power density of conventional catalyst layers (CLs) increased from 0.28 to 0.64 W/cm² at 0.45 V with the increase in Pt amount in commercial catalyst from 20% to 70% Pt/C for H₂/Air feed. In the case of H₂/O₂ feed, power density of CLs increased from 0.64 to 1.29 W/cm² at 0.45 V for conventional catalyst layers prepared with Tanaka. Increasing Pt load from 0.4 to 1.2 mg/cm², improved kinetic activity at low current density region in both feeding conditions. Scattering electron microscopy (SEM) images revealed that thickness of the catalyst layers (CLs) increases by increasing Pt load. Electrochemical impedance spectroscopy (EIS) results revealed that thinner CLs have lower charge transfer resistance than thicker CLs. Inclusion of 30 wt % Polytetrafluoroethylene (PTFE) nanoparticles in catalyst ink enhanced cell performance for the electrodes manufactured with 20% Pt/C at higher current densities. However, in the case of 70% Pt/C, performance enhancement was not observed. Cyclic voltammetry (CV) results revealed that 20% Pt/C had higher (77 m²/g) electrochemical surface area (ESA) than 70% Pt/C (65 m²/g). In terms of hydrophobic powders, ESA of 30PTFE prepared with 70% Pt/C was higher than 30PTFE prepared with 20 %Pt/C. X-Ray Diffractometer (XRD) results showed that diameter of Pt particles of 20% Pt/C was 2.5 nm, whereas, it was 3.5 nm for 70% Pt/C, which confirms CV results. Nitrogen physisorption results revealed that primary pores of hydrophobic catalyst powder prepared with 70% Pt/C was almost filled (99%) with Nafion and PTFE.     

Controllable synthesis of PtPd nanocubes on graphene as advanced catalysts for ethanol oxidation

PtPd nanocubes (NCs) were uniformly deposited on the reduced graphene oxides (RGOs) via a one-pot solvothermal reduction. These PtPd NCs were enclosed with (100) facet. Their size can be tuned from 11 to 27 nm by controlling their composition. Under the optimum atomic ratio of Pt/Pd (1:5), the as-prepared RGO-supported PtPd NCs show a superior catalytic efficiency of ethanol oxidation reaction (EOR) with a specific activity of 2.3 mA cm^?2 and a mass activity of 1.08 A mg^?1 Pt, far above those for the RGO-supported Pt nanoparticles (0.3 mA cm^?2 for specific activity and 0.018 A mg^?1 Pt for mass activity). Besides, these EOR catalysts exhibit a high CO-tolerance without significant current decay during steady-state polarization at 0.6 V over 4000 s. Their durability is also remarkable with only 8.9% loss of their electrochemical surface area (ECSA) after 10 000 cycles of voltammetric test.     

Preparation and electroactivity of polymer-functionalized graphene oxide-supported platinum nanoparticles catalysts

Polymer-functionalized graphene oxide or pristine graphene oxide supported platinum nanoparticles (Pt NPs) was prepared to study the surface modification effects. The catalysts were characterized by transmission electron microscopy, energy dispersive spectrometry, X-ray diffraction and thermogravimetric analysis. The electrochemical activities of Pt NPs were measured by cyclic voltammograms. The poly(diallyldimethylammonium chloride) (PDDA) was used as a modifier agent which formed a functionalized layer on graphene oxide (GO) sheets. As a result, the electrochemical active surface area (ESA) of PDDA functionalized GO supported Pt (Pt/PDDA–graphene) was shown to 66 m²/g that indicated higher hydrogen adsorption amount than 55 m²/g of the pristine Pt/graphene. In addition, an average particle size of Pt/PDDA–graphene NPs was measured to 1.8 nm slightly smaller than 2.0 nm of pristine Pt/graphene NPs.     

One-pot solvothermal synthesis of PdCu nanocrystals with enhanced electrocatalytic activity toward glycerol oxidation and hydrogen evolution

The catalytic capability of bimetallic nanocatalysts is closely correlated with their size, shape, and crystal structures. Herein, a facile one-pot solvothermal strategy is designed to fabricate uniform spherical PdCu nanocrystals (NCs) assembled by many smaller grains. Oeylamine (OAm) is acted as the reaction solvent and reductant. KBr and hexadecylpyridinium chloride monohydrate (HDPC) are used as the capping agent and surfactant to avoid the aggregation, respectively. The architectures possess larger electrochemically active surface area (ECSA) of 13.6 m² g^?1 than commercial Pd black (4.4 m² g^?1), showing the improved catalytic ability for glycerol oxidation reaction (GOR) in alkaline electrolyte in contrast with Pd black. Besides, the obtained catalyst exhibits more positive onset potential (?56 mV) and Tafel slope (51 mV decade^?1) toward hydrogen evolution reaction (HER) in acidic media relative to commercial Pd/C, albeit with their performance bellow commercial Pt/C catalyst.     

Nickel phosphate as advanced promising electrochemical catalyst for the electro-oxidation of methanol

Mesoporous nickel phosphate nanotube (Meso NiPO NT) and mesoporous nickel phosphate nanosheet (Meso NiPO NS) are developed as catalysts for electrochemical methanol oxidation. Conventional mesoporous nickel phosphate which is composed of stacked nanocrystals (Meso NiPO), microporous VSB-5 and commercial nickel oxide (NiO) are used as control materials. Notably, both Meso NiPO NT (40.83 mA cm^?2) and Meso NiPO NS (44.97 mA cm^?2) exhibit much higher oxidation current density than VSB-5 (13.41 mA cm^?2), Meso NiPO (19.85 mA cm^?2) and commercial NiO (0.87 mA cm^?2). As for the durability test on these materials modified fluorine-doped tin dioxide transparent conductive glass (FTO) electrodes, Meso NiPO NT displays the most stable performance and still retains 91.3% electrochemical activity, which perhaps benefit from its nanotube structure and large specific surface area (99.6 m²/g). Moreover, Meso NiPO NT has higher activity and more excellent stability than many of the previously reported nickel-based materials, suggesting a potential development for direct methanol fuel cells.     

TiC supported Pt-based nanoparticles: Facile sonochemical synthesis and electrocatalytic properties for methanol oxidation reaction

In this study, we synthesized Pt nanoparticles (NPs) with small amounts of Mn (≤11.4 at%) included, hence Pt(Mn) NPs, on titanium carbide (TiC) support (denoted as Pt(Mn)/TiC) in three different Pt loadings (16.0–33.2 wt%) and investigated their electrocatalytic performance for methanol oxidation reaction (MOR) in acidic media. The syntheses were achieved via one-pot sonochemical reactions of Pt(acac)₂ and Mn(acac)₂ (acac = acetylacetonate) in ethylene glycol in the presence of TiC particles and without any other additives. The Pt(Mn) NPs were uniform in size (4–6 nm) and were evenly deposited on the TiC surface. The electronic structure of Pt in Pt(Mn)/TiC samples, probed by X-ray photoelectron spectroscopy (XPS) and other techniques, is systematically changed with the Pt loading, by which enhanced electrocatalytic properties from pure Pt are expected. In addition, the TiC support contributes to enhancing the electrocatalytic properties of Pt(Mn) NPs through its high conductivity, chemical resistance to corrosion, and the TiO₂ formed on the surface which exerts the bifunctional mechanism to reduce the CO poisoning on Pt. The electrochemical performance of Pt(Mn)/TiC was investigated by the rotating disk electrode (RDE) technique. The specific and mass MOR currents are, respectively, 1.6–2.2 and 0.9–1.4 times higher in Pt(Mn)/TiC samples than in commercial Pt/C. All Pt(Mn)/TiC samples show 93–98% of the initial electrochemical surface areas after 3000 potential cycles, superior electrochemical stability to commercial Pt/C (86%).     

Electrochemical fabrication of long-term stable Pt-loaded PEDOT/graphene composites for ethanol electrooxidation

Layered electrochemically reduced graphene oxide (ER-GO) sheets incorporated with poly(3,4-ethylenedioxythiophene) (PEDOT) have been fabricated as an efficient support for Pt nanoparticles on a glassy carbon (GC) electrode. The as-prepared Pt-loaded PEDOT/ER-GO composite electrode exhibits not only the high mass peak current density (390 A g⁻¹) but also the good long-term catalytic stability toward the ethanol electrooxidation. The Pt/PEDOT/ER-GO also shows stronger tolerance to poisoning species compared with the commercial JM 20% Pt/C electrode. The high electrocatalytic activity of Pt/PEDOT/ER-GO is mainly described to the good electrochemical activity of PEDOT/ER-GO composites and the well-dispersed Pt nanoparticles resulting in the large electrochemical active surface area of Pt (47.1 m² g⁻¹).     

Efficient hydrogen evolution catalysis triggered by electrochemically anchored platinum nano-islands on functionalized-MWCNT

We report the electrochemical deposition (ECD) of platinum nano-islands (Pt NIs) on functionalized multi-walled carbon nanotubes (ECD Pt NIs@f-MWCNT) as an efficient electrocatalyst for the hydrogen evolution reaction (HER). Pristine MWCNT was acid treated to induce the number of oxygen functional groups on the surface and enhances the wettability. Thereafter, Pt nanoparticles (Pt Nps) were deposited by a simple electrodeposition technique on the oxygen enriched MWCNT surface. The Pt NIs@f-MWCNT has been physicochemically characterized using X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), Raman spectroscopy and X-ray photoelectron Spectroscopy (XPS). The TEM analysis showed the presence of Pt NIs on MWCNT wherein, the NIs were made up of small Pt nanoclusters of ～4 nm in dimension. The electrochemical HER studies were carried out using linear sweep voltammetry (LSV), Tafel polarization and electrochemical impedance spectroscopy (EIS). An overpotential (?) of ?84 mV was obtained at a current density (j) of ?10 mA/cm². The amount of Pt loading has been optimized through electrodeposition. Enhanced HER activity was observed with a Pt loading of 3.8 μg/cm². In order to ascertain the durability of the catalyst, accelerated degradation test (ADT) was carried out for 10,000 cycles at a scan rate (?) of 100 mV/s. The turnover frequency (TOF) was estimated to be 6.3 s^?1 at ? = ?70 mV.     

Pt/Fe-NF electrode with high double-layer capacitance for efficient hydrogen evolution reaction in alkaline media

The electrode with high catalytic activity, low hydrogen overpotential and low cost is desired for hydrogen evolution reaction (HER) via electrocatalytic water splitting. In this study, Pt/Fe-Ni foam (Pt/Fe-NF) electrode was synthesized via cathodic electrodeposition followed by impregnation deposition. Physical and electrochemical properties of Pt/Fe-NF, NF and Pt/NF electrodes were characterized by various techniques. The Pt/Fe-NF electrode exhibited better electrochemical activity for HER under alkaline condition than those of Pt/NF and NF electrodes, owing to the introduction of zero valences Pt and Fe onto the NF, and synergetic effect resulted from the formation of Fe-Ni alloy. Furthermore, Pt/Fe-NF electrode showed extremely high double-layer capacitance (69.1 mFcm^?2), suggesting high active sites for the Pt/Fe-NF. Tafel slope of Pt/Fe-NF was 59.9 mV dec^?1, indicating that the Volmer-Heyrovsky HER mechanism was the rate-limiting step. The Pt/Fe-NF electrode with great electrocatalytic activity is a promising electro-catalyst for industrial hydrogen production from alkaline electrolyte.     

Research on a novel Ni-doped TiN modified N-doped CNTs supported Pt catalysts and their synergistic effect for methanol electrooxidation

A novel Ni-doped TiN modified N-doped CNTs hybrid nanotubes (N-CNTs@TiNiN) is constructed and serves as hybrid support for the platinum (Pt) catalyst. We prepare the N-CNTs@TiNiN support by a solvothermal process followed by a nitriding process. It is used as anodic catalyst support to test methanol electrooxidation. By contrast, the current density of Pt/N-CNTs (0.34 A mgpt^?1) is nearly 1.31 times more than Pt/CNTs (0.26 A mgpt^?1) while Pt/TiNiN (0.56 A mgpt^?1) is almost 1.33 times as much as Pt/TiN (0.42 A mgpt^?1). What's more, among all the catalysts investigated in this work, the novel Pt/N-CNTs@TiNiN (0.86 A mgpt^?1) shows the highest reactivity for methanol oxidation, which is also much more active and durable than the commercial JM Pt/C catalyst, showing only slight activity variation even after 12 000 potential cycles. The synthetic Pt/N-CNTs@TiNiN catalyst is researched on its electrocatalytic performance toward methanol electrooxidation and the high activity and durability might be mainly attributed to the electron transfer due to the synergistic effect of the robust TiNiN NPs and N-CNTs by inducing both co-catalytic and electronic effects.     

Synthesis of polypyrrole (PPy) based porous N-doped carbon nanotubes (N-CNTs) as catalyst support for PEM fuel cells

In this study, it was aimed to synthesize catalytically active, high surface area carbon nanotubes (CNTs) by means of nitrogen doping (N-doping). The synthesized nitrogen doped carbon nanotubes (N-CNTs) were used as Pt catalyst support in order to improve oxygen reduction reaction (ORR) kinetics at the cathode electrode in PEM fuel cell. Polypyrrole (PPy) was served as both carbon and nitrogen source and FeCl₃ solution was used as oxidizing agent in the synthesis procedure of N-CNTs. Chemical activation of the materials was made with potassium hydroxide (KOH) solution during 12 and 18 h time periods. It was considered that activation period is of great importance on the properties of the synthesized PPy based N-CNTs. 12 h activated N-CNTs gave higher surface area (1607.2 m²/g) and smaller micropore volume (0.355 cm³/g) in comparison to 18 h activated N-CNTs having smaller surface area (1170.7 m²/g) and higher micropore volume (0.383 cm³/g). PEM fuel cell performance results showed that 12 h activated N-CNTs are better catalyst supports than 18 h activated N-CNTs for Pt nanoparticle decoration.     

Electrochemically synthesized polypyrrole/MWCNTs-Al2O3 ternary nanocomposites supported Pt nanoparticles toward methanol oxidation

As known, a good support enhances the activity and durability of any catalyst. In the current study, polypyrrole (PPY)/nanocomposite (MWCNTs and Al₂O₃) films were fabricated by electrochemical polymerization of pyrrole solution with a certain amount of nanoparticles on titanium substrates and were used as new support materials for Pt catalyst. The modified electrodes were characterized by Fourier transform infrared (FT-IR) spectroscopy, field-emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray analysis (EDX) techniques. High catalytic activity and long-time stability toward methanol oxidation of Pt/PPY–MWNTs-αAl₂O₃ catalyst have also been verified by cyclic voltammetry results and chronoamperometric response measurements. This catalyst exhibits a vehemently high current density (345.03 mA cm^?2) and low peak potential (0.74 v) for methanol oxidation. Other electrochemical measurements (electrochemical impedance spectroscopy (EIS), CO stripping voltammetry and Tafel test) clearly confirmed that Pt/PPY–MWNTs-αAl₂O₃/Ti electrode has a better performance toward methanol oxidation compared to the other electrodes and that can be used as a promising electrode material for application in direct methanol fuel cells (DMFCs).     

Synthesis of bimetallic iron ferrite Co0.5Zn0.5Fe2O4 as a superior catalyst for oxygen reduction reaction to replace noble metal catalysts in microbial fuel cell

A low-cost electrochemically active oxygen reduction reaction (ORR) catalyst is obligatory for making microbial fuel cells (MFCs) sustainable and economically viable. In this endeavour, a highly active surface modified ferrite, with Co and Zn bimetal in the ratio of 1:1 (w/w), Co_0.5Zn_0.5Fe₂O₄ was synthesised using simple sol-gel auto combustion method. Physical characterisation methods revealed a successful synthesis of nano-scaled Co_0.5Zn_0.5Fe₂O₄. For determination of ORR kinetics of cathode, using Co_0.5Zn_0.5Fe₂O₄ catalyst, electrochemical studies viz. cyclic voltammetry and electrochemical impedance spectroscopy were conducted, which demonstrated excellent reduction current response with less charge transfer resistance. These electrochemical properties were observed to be comparable with the results obtained for cathode using 10% Pt/C as a catalyst on the cathode. The MFC using Co_0.5Zn_0.5Fe₂O₄ catalysed cathode could produce a maximum power density of 21.3 ± 0.5 W/m³ (176.9 ± 4.2 mW/m²) with a coulombic efficiency of 43.3%, which was found to be substantially higher than MFC using no catalyst on the cathode 1.8 ± 0.2 W/m³ (15.2 ± 1.3 mW/m²). Also, the specific power recovery per unit cost for MFC with Co_0.5Zn_0.5Fe₂O₄ catalysed cathode was found to be 4 times higher as compared to Pt/C based MFC. This exceptionally low-cost cathode catalyst has enough merit to replace costly cathode catalyst, like platinum, for scaling up of the MFCs.     

Graphene based catalyst supports for high temperature PEM fuel cell application

In this study, the effect of graphene nanoplatelet (GNP) and graphene oxide (GO) based carbon supports on polybenzimidazole (PBI) based high temperature proton exchange membrane fuel cells (HT-PEMFCs) performances were investigated. Pt/GNP and Pt/GO catalysts were synthesized by microwave assisted chemical reduction support. X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Brauner, Emmet and Teller (BET) analysis and high resolution transmission electron microscopy (HRTEM) were used to investigate the microstructure and morphology of the as-prepared catalysts. The electrochemical surface area (ESA) was studied by cyclic voltammetry (CV). The results showed deposition of smaller Pt nanoparticles with uniform distribution and higher ECSA for Pt/GNP compared to Pt/GO. The Pt/GNP and Pt/GO catalysts were tested in 25 cm² active area single HT-PEMFC with H₂/air at 160 °C without humidification. Performance evaluation in HT-PEMFC shows current densities of 0.28, 0.17 and 0.22 A/cm² for the Pt/GNP, Pt/C and Pt/GO catalysts based MEAs at 160 °C, respectively. The maximum power density was obtained for MEA prepared by Pt/GNP catalyst with H₂/Air dry reactant gases as 0.34, 0.40 and 0.46 W/cm² at 160 °C, 175 °C and 190 °C, respectively. Graphene based catalyst supports exhibits an enhanced HT-PEMFC performance in both low and high current density regions. The results indicate the graphene catalyst support could be utilized as the catalyst support for HT-PEMFC application.     

Facile one-step synthesis of supportless porous AuPtPd nanocrystals as high performance electrocatalyst for glucose oxidation reaction

Direct glucose fuel cells (DGFCs) received great interest due to non-toxicity, low cost, and renewability. Herein, we demonstrated the synthesis of novel porous AuPtPd nanocrystals (NCs) via plausible one-pot synthesis route. This was implemented by reduction of the metal precursors with l-ascorbic acid in the presence of polyvinylpyrrolidone (PVP) as a structure-directing agent. TEM (transmission electron microscopy) images of the as-synthesized nanocrystals depicted porous nanodendritic morphology with particle size ranging from 20 to 30 nm. The catalytic performance of AuPtPd NCs was investigated towards glucose oxidation reaction (GOR) in alkaline medium compared to AuPt, PtPd, and Pt/C. The delivered maximum oxidation current density over AuPtPd was 10.1 mA cm⁻², which is nearly 1.4, 1.8, and 3.5 times greater than AuPt, PtPd, and Pt/C, respectively. Additionally, the ternary electrocatalyst exhibited higher electrochemical stability compared to binary alloys and Pt/C counterparts. Furthermore, AuPtPd revealed lower Tafel slope for GOR compared to binary alloys and Pt/C which affirm enhanced GOR kinetics. The outstanding catalytic performance of AuPtPd NCs was attributed to the synergistic effect of the alloying elements and the high anti-poisoning effect of Au and Pd metals which facilitates the adsorption of surface hydroxyls (OH)_ads on the catalyst active sites and enhances the oxidation kinetics.     

Development of a simple and efficient method to prepare a platinum-loaded carbon electrode for methanol electrooxidation

In this study, a simple and efficient electrochemical method was developed to prepare platinum (Pt) nanoparticles modified pencil graphite electrode (PGE) to use in direct methanol fuel cells. This method is based on two successive steps including the electrochemical pre-treatment of PGE via potential sweeping in the range of −1.0 V and +2.0 V and subsequent electrochemical plating of Pt nanoparticles in a wide potential range (+2.0 V: 1.0 V). Both the electrochemical pre-treatment of PGE and to use a wide potential range in the electrochemical Pt plating tremendously increased the effective surface area, the intensity of surface functional groups (hydroxyl, carbonyl, carboxyl, etc.), the electron transfer rate and the amount of Pt loading on the electrode surface, which greatly improved methanol electrooxidation activity of the electrode. The increase in the activity of the electrode reached to 16.3 times according to the classical Pt electroplating process. The electrodes were characterized by cyclic voltammetry, electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy measurements. The stability of the electrodes was tested via cyclic voltammetry and chronoamperometry measurements. The electrochemical surface area of the electrode prepared here was calculated as 39.46 m^2 g-1, which was 39% higher than that of commercial Pt/C catalyst (28.4 m^2 g-1). The results showed that the proposed modification process can be seen as a simple and efficient alternative for the preparation of Pt-loaded carbon electrodes which can be used in direct methanol fuel cells.