Fabrication of a novel PtPbBi/C catalyst for ethanol electro-oxidation in alkaline medium

One-Pot Microwave-Assisted Synthesis of Graphene-Supported PtCoM (M = Mn, Ru, Mo) Catalysts for Low-Temperature Fuel Cells

In this study, one-pot microwave-assisted synthesis was used to fabricate the graphene (GR)-supported PtCoM catalysts where M = Mn, Ru, and Mo. The catalysts with the molar ratios of metals Pt:Co:Mn, Pt:Co:Ru, and Pt:Co:Mo equal to 1:3:1, 1:2:2, and 7:2:1, respectively, were prepared. Catalysts were characterized using Transmission Electron Microscopy (TEM). The electrocatalytic activity of the GR-supported PtCoMn, PtCoRu, and PtCoMo catalysts was evaluated toward methanol oxidation in an alkaline medium employing cyclic voltammetry and chrono-techniques. The most efficient electrochemical characteristics demonstrated the PtCoMn/GR catalyst with a current density value of 144.5 mA cm−2, which was up to 4.8 times higher than that at the PtCoRu(1:2:2)/GR, PtCoMo(7:2:1)/GR, and bare Pt/GR catalysts.

Electrocatalytic performance of NiNH2BDC MOF based composites with rGO for methanol oxidation reaction

Present work comprehensively investigated the electrochemical response of Nickel-2 Aminoterephthalic acid Metal-Organic Framework (NiNH2BDC) and its reduced graphitic carbon (rGO) based hybrids for methanol (CH3OH) oxidation reaction (MOR) in an alkaline environment. In a thorough analysis of a solvothermally synthesized Metal-Organic Frameworks (MOFs) and its reduced graphitic carbon-based hybrids, functional groups detection was performed by FTIR, the morphological study by SEM, crystal structure analysis via XRD, and elemental analysis through XPS while electrochemical testing was accomplished by Chronoamperometry (CA), Cyclic Voltametric method (CV), Electrochemically Active Surface Area (EASA), Tafel slope (b), Electron Impedance Spectroscopy (EIS), Mass Activity, and roughness factor. Among all the fabricated composites, NiNH2BDC MOF/5 wt% rGO hybrid by possessing an auspicious current density (j) of 267.7 mA/cm2 at 0.699 V (vs Hg/HgO), a Tafel slope value of 60.8 mV dec-1, EASA value of 15.7 cm2, and by exhibiting resistance of 13.26 Ω in a 3 M CH3OH/1 M NaOH solution displays grander electrocatalytic activity as compared to state-of-the-art platinum-based electrocatalysts.

C2 Alcohol Oxidation Boosted by Trimetallic PtPbBi Hexagonal Nanoplates

The exploration of ternary Pt-based catalysts represents a new trend for the application of electrocatalysts in fuel cells. In the present study, intermetallic PtPbBi hexagonal nanoplates (HNPs) with a hexagonal close-packed structure have been successfully synthesized via a facile solvothermal synthesis approach. The optimized PtPbBi HNPs exhibited excellent mass activity in the ethanol oxidation reaction (8870 mA mg^-1_Pt) in an alkaline ethanol solution, which is 12.7 times higher than that of JM Pt/C. Meanwhile, the mass activity of PtPbBi HNPs in an ethylene glycol solution (10,225 mA mg^-1_Pt) is 1.85 times higher than that of JM Pt/C. In particular, its catalytic activity is better than that of most reported Pt-based catalysts. In addition, the optimized PtPbBi HNPs also show a better operational durability than commercial Pt/C. For the ethylene glycol oxidation reaction, a mass activity of 42.7% was retained even after a chronoamperometric test for 3600 s, which is rare among the reported Pt-based catalysts. By combining X-ray photoelectron spectroscopy and electrochemical characterization, we reveal the electron transfer between Pt, Pb, and Bi; this would lead to weakened CO adsorption and enhanced OH adsorption, thereby promoting the removal of toxic intermediates and ensuring that PtPbBi HNP samples have high activity and excellent stability. This work can inspire the design and synthesis of Pt-based nanocatalysts.

Au Nanoparticles Modified with Pt, Ru and SnO2 as Electrocatalysts for Ethanol Oxidation Reaction in Acids

The anodic reaction in direct ethanol fuel cells (DEFCs), ethanol oxidation reaction (EOR) faces challenges, such as incomplete electrooxidation of ethanol and high cost of the most efficient electrocatalyst, Pt in acidic media at low temperature. In this study, core-shell electrocatalysts with an Au core and Pt-based shell (Au@Pt) are developed. The Au core size and Pt shell thickness play an important role in the EOR activity. The Au size of 2.8 nm and one layer of Pt provide the most optimized performance, having 6 times higher peak current density in contrast to commercial Pt/C. SnO₂ as a support also enhances the EOR activity of Au@Pt by 1.73 times. Further modifying the Pt shell with Ru atoms achieve the highest EOR current density that is 15 and 2.5 times of Pt/C and Au@Pt. Our results suggest the importance of surface modification in rational design of advanced electrocatalysts.

Surfactant-Free One-Pot Synthesis of Homogeneous Trimetallic PtNiCu Nanoparticles with Size Control by Using Glycine

Homogeneous platinum alloy nanoparticles (NPs) are of great interest to the electrocatalytic community for potential use in various fuel cell electrodes. Increasing the surface area available per unit mass by decreasing the size of NPs while maintaining or improving activity is one of the key tasks of fuel cell catalysis. Achieving both in a synthesis of multielement NPs is still a challenging workup. In this investigation, we report the use of glycine as a size control agent to make ultrasmall homogeneous trimetallic PtNiCu NPs within 2-5 nm range. The mechanistic roles of dimethyl formamide (DMF), formaldehyde, water, and glycine are explored to understand the formation of these small NPs. Interestingly, it was observed that these PtNiCu NPs exhibited substantially enhanced mass activities toward the electro-oxidation of ethanol in comparison to commercial Pt black.

Green dual-template synthesis of AgPd core-shell nanoparticles with enhanced electrocatalytic activity

A key challenge in developing an ethanol oxidation reaction is nontoxic fabrication of highly active stable and low-cost catalysts. Here we design a green synthetic strategy of AgPd bimetallic nanosphere by a dual-template cascade method. The Pd nanoshell is firstly prepared using Vapreotide acetate as a primary template, and then the Ag nanoshell acts as a secondary template for the distribution of AgPd alloy nanoparticles. The AgPd nanoparticles have core-shell structures and various sizes, and their shell thicknesses are tuned by controlling the amount of PdCl₂. The six different samples are prepared, named AgPd-1, AgPd-2, AgPd-3, AgPd-4, AgPd-5, and AgPd-6, respectively. The mass current density of AgPd-5, is higher 3.87 times that of commercial Pd/C, and exhibits the best ethanol oxidation reaction activity and long-term stability. The main reasons are that the AgPd-5 possessed excellent specific surface area due to their rough structure, and Ag can remove more CO-like species. This is the first time a Vapreotide acetate/Ag-template method has been used to synthesize a AgPd core-shell structure, which would have broad application prospects for direct ethanol fuel cells.

Development of Nickel-BTC-MOF-Derived Nanocomposites with rGO Towards Electrocatalytic Oxidation of Methanol and Its Product Analysis

In this study, electrochemical oxidation of methanol to formic acid using the economical and highly active catalytic Nickel Benzene tricarboxylic acid metal organic framework (Ni-BTC-MOF) and reduced graphene oxide (rGO) nanocomposites modified glassy carbon electrode GCE in alkaline media, which was examined via cyclic voltammetry technique. Nickel based MOF and rGO nanocomposites were prepared by solvothermal approach, followed by morphological and structural characterization of prepared samples through X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and energy dispersive X-ray (EDX) analysis. The electrochemical testing of synthesized materials represents the effect of the sequential increase in rGO concentration on electrocatalytic activity. The Ni-BTC/4 wt % rGO composite with a pronounced current density of 200.22 mA/cm2 at 0.69 V versus Hg/HgO electrode at 50 mV/s was found to be a potential candidate for methanol oxidation in Direct Methanol Fuel Cell (DMFC) applications. Product analysis was carried out through Gas Chromatography (GC) and Nuclear Magnetic Resonance (NMR) spectroscopy, which confirmed the formation of formic acid during the oxidation process, with approximately 62% yield.

Efficient catalytic hydrogen generation by intermetallic platinum-lead nanostructures with highly tunable porous feature

The water-gas shift (WGS) reaction is an essential industrial reaction for upgrading hydrogen (H₂) by removing carbon monoxide (CO), while highly efficient platinum (Pt)-based catalysts for WGS with simultaneously high activity and stability are still yet to be developed due to the poisoning issue during the reaction. Herein, we report on the porous PtPb peanut nanocrystals (porous PtPb PNCs) and porous PtPb octahedron nanocrystals (porous PtPb ONCs) with controllable ratios of Pt/Pb as extremely active and stable catalysts towards WGS reaction. It exhibits the composition-dependent activity with porous PtPb PNCs-40/ZnO being the most active for WGS to H₂, 16.9 times higher than that of the commercial Pt/C. The porous PtPb PNCs-40/ZnO also display outstanding durability with barely activity decay and negligible structure and composition changes after ten successive reaction cycles. X-ray photoelectron spectroscopy (XPS) results reveal that the suitable binding energy of Pt 4f_7/2 and the high ratio of Pt(0) to Pt(II) in porous PtPb PNCs/ZnO and porous PtPb ONCs/ZnO are crucial for the enhanced WGS activity. The CO stripping results indicate the optimized CO adsorption strength on the Pt surface ensure the excellent WGS activity and the outstanding durability. The present work demonstrates an important advance in tuning the porous metal nanomaterials as highly efficient and durable catalysts for catalysis, energy conversion and beyond.

The Modification of Pt/Graphene Composites with Oxophilic Metal Bi (Bi2O3) and Its Dual-Functional Electro-Photo Catalytic Performance

The Pt-Bi (Bi2O3)/GNs (PVP) composite was synthesized using aqueous solution synthesis and characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and Raman spectroscopy. It was found that the water-soluble polyvinyl pyrrolidone (PVP) helped to tune the particles’ morphology, resulting in a uniform distribution of Pt-Bi nanoclusters on the surface of graphene. Cyclic voltammetry, chronoamperometry and linear scanning voltammetry (LSV) were used to study the electrocatalytic properties towards a methanol oxidation reaction (MOR) and an oxygen reduction reaction (ORR). The results show that Pt-Bi (Bi2O3)/GNs (PVP) exhibits superior bifunctional electrocatalytic properties for both MOR and ORR, mainly due to the introduction of oxophilic Bi species and the better dispersion of the Pt-Bi nanoclusters. In particular, the electro-photo catalysis for both MOR and ORR occurred under simulated sunlight irradiation due to the existence of photo-responsive Bi species, which is helpful for converting solar energy into electric energy during a traditional electrocatalytic process.

Facile Aqueous-Phase Synthesis of the PtAu/Bi2O3 Hybrid Catalyst for Efficient Electro-Oxidation of Ethanol

In this work, we present a facile aqueous-phase synthesis of a hybrid catalyst consisting of PtAu alloy supported on Bi₂O₃ microspheres. Multistep reduction of HAuCl₄ and K₂PtCl₄ salts on Bi₂O₃ and subsequent annealing lead to the formation of this hybrid catalyst. To the best of our knowledge, this is the first report of using Bi₂O₃ as a catalyst support in fuel cell applications. The material was characterized by powder X-ray diffraction and various microscopic techniques. This composite showed remarkable activity as well as stability toward the electro-oxidation of ethanol in comparison to commercially available Pt/C. The order of the reactivity was found to be commercial Pt/C (50.4 mA/m²mg_Pt^-1) < Pt/Bi₂O₃(10) (108 mA/m²mg_Pt^-1) < PtAu/Bi₂O₃(10) (459 mA/m²mg_Pt^-1). The enhancement in the activity can be explained through cooperative effects, namely, ligand effects of gold and Bi₂O₃ support, which helps in removing carbon monoxide molecules to avoid the poisoning of the Pt active sites.

3D Platinum-Lead Nanowire Networks as Highly Efficient Ethylene Glycol Oxidation Electrocatalysts

A large-scalable wet-chemical approach to create networked Pt-Pb nanowires (NWs) with tunable compositions is reported. Due to their 3D networked structure, alloy effect, rich defects/steps, and antipoisoning property of Pb, the networked Pt-Pb NWs exhibit the best activity and durability towards ethylene glycol oxidation reaction (EGOR), compared with the networked Pt NWs and Pt/C.

Multisource Synergistic Electrocatalytic Oxidation Effect of Strongly Coupled PdM (M = Sn, Pb)/N-doped Graphene Nanocomposite on Small Organic Molecules

A series of palladium-based catalysts of metal alloying (Sn, Pb) and/or (N-doped) graphene support with regular enhanced electrocatalytic activity were investigated. The peak current density (118.05 mA cm(-2)) of PdSn/NG is higher than the sum current density (45.63 + 47.59 mA cm(-2)) of Pd/NG and PdSn/G. It reveals a synergistic electrocatalytic oxidation effect in PdSn/N-doped graphene Nanocomposite. Extend experiments show this multisource synergetic catalytic effect of metal alloying and N-doped graphene support in one catalyst on small organic molecule (methanol, ethanol and Ethylene glycol) oxidation is universal in PdM(M = Sn, Pb)/NG catalysts. Further, The high dispersion of small nanoparticles, the altered electron structure and Pd(0)/Pd(II) ratio of Pd in catalysts induced by strong coupled the metal alloying and N-doped graphene are responsible for the multisource synergistic catalytic effect in PdM(M = Sn, Pb) /NG catalysts. Finally, the catalytic durability and stability are also greatly improved.