Bimetallic Pd96Fe4 nanodendrites embedded in graphitic carbon nanosheets as highly efficient anode electrocatalysts

Rapid synthesis of Palladium-Platinum-Nickel ultrathin porous nanosheets with high catalytic performance for alcohol electrooxidation

Bimetallic two-dimensional (2D) nanomaterials are widely used in electrocatalysis owing to their unique physicochemical properties, while trimetallic 2D materials of porous structures with large surface area are rarely reported. In this paper, a one-pot hydrothermal synthesis of ternary ultra-thin PdPtNi nanosheets is developed. By adjusting the volume ratio of the mixed solvents, PdPtNi with porous nanosheets (PNSs) and ultrathin nanosheets (UNSs) was prepared. The growth mechanism of PNSs was investigated through a series of control experiments. Notably, thanks to the high atom utilization efficiency and fast electron transfer, the PdPtNi PNSs have remarkable activity of methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR). The mass activities of the well-tuned PdPtNi PNSs for MOR and EOR were 6.21 A mg-1 and 5.12 A mg-1, respectively, much higher than those of commercial Pt/C and Pd/C. In addition, after durability test, the PdPtNi PNSs exhibited desirable stability with the highest retained current density. Therefore, this work provides a significant guidance for designing and synthesizing a new 2D material with excellent catalytic performance toward direct fuel cells applications.

Fe-Pd nanoflakes decorated on leached graphite disks for both methanol and formic acid electrooxidation with excellent electrocatalytic performance

This paper introduces a unique and simple method for fabricating of inexpensive electrocatalysts for use in direct methanol fuel cells. The leached Fe1-Pd1 NFs/graphite (leached Fe1-Pd1/graphite) disk electrode was successfully obtained via uniform dispersion of Zn powder into the matrix of commercial graphite powder (98%), pressing under optimized pressure followed by the treatment in H2SO4 solution containing Fe+2 and Pd+2 cations, leading to the partial leaching out of Zn from graphite matrix, as well as partial electroless substitution of Fe-Pd nanoflakes with Zn metal. Based on the morphology studies, binary Fe-Pd nanoflakes with a large surface area uniformly dispersed on the leached graphite disk. The leached Fe-Pd/G disk showed the exceptional electrocatalytic activity toward methanol and formic acid oxidation without electrocatalyst poisoning being observed, in contrast to the leached Pd/graphite and leached Fe/graphite disks. This is due to the high surface area, and synergistic effect of Pd and Fe. The findings of this work may be used for the mass manufacture of graphite-based disks for commercial fuel cell applications using available graphite powders. The linear range of washed Fe1-Pd1/G electrocatalyst for measuring methanol was about 0.1-1.3 M, and its detection limit was calculated at about 0.03 M. Furthermore, the linear range of the nanocatalyst for measuring formic acid was about 0.02-0.1 M, and its detection limit was calculated at about 0.006 M.

Radiolysis-Assisted Direct Growth of Gold-Based Electrocatalysts for Glycerol Oxidation

The electrocatalytic oxidation of glycerol by metal electrocatalysts is an effective method of low-energy-input hydrogen production in membrane reactors in alkaline conditions. The aim of the present study is to examine the proof of concept for the gamma-radiolysis-assisted direct growth of monometallic gold and bimetallic gold-silver nanostructured particles. We revised the gamma radiolysis procedure to generate free-standing Au and Au-Ag nano- and micro-structured particles onto a gas diffusion electrode by the immersion of the substrate in the reaction mixture. The metal particles were synthesized by radiolysis on a flat carbon paper in the presence of capping agents. We have integrated different methods (SEM, EDX, XPS, XRD, ICP-OES, CV, and EIS) to examine in detail the as-synthesized materials and interrogate their electrocatalytic efficiency for glycerol oxidation under baseline conditions to establish a structure-performance relationship. The developed strategy can be easily extended to the synthesis by radiolysis of other types of ready-to-use metal electrocatalysts as advanced electrode materials for heterogeneous catalysis.

Controllable Synthesis of Web-Footed PdCu Nanosheets and Their Electrocatalytic Applications

Morphological control of noble-metal-based nanocrystals has attracted enormous attention because their catalytic behaviors can be optimized well by adjusting the size and shape. Herein, the controllable synthesis of web-footed PdCu nanosheets via a facile surfactant-free method is reported. It is discovered that the Cu(II) precursor in this synthetic system displays a critical role in growing branches along the lateral of nanosheets. This work demonstrates a Pd-based alloy nanoarchitecture for efficient and stable electrocatalysis of both ethanal and formic acid oxidation reactions.

Conducting Polymer-Based Nanohybrids for Fuel Cell Application

Carbon materials such as carbon graphitic structures, carbon nanotubes, and graphene nanosheets are extensively used as supports for electrocatalysts in fuel cells. Alternatively, conducting polymers displayed ultrahigh electrical conductivity and high chemical stability havegenerated an intense research interest as catalysts support for polymer electrolyte membrane fuel cells (PEMFCs) as well as microbial fuel cells (MFCs). Moreover, metal or metal oxides catalysts can be immobilized on the pure polymer or the functionalized polymer surface to generate conducting polymer-based nanohybrids (CPNHs) with improved catalytic performance and stability. Metal oxides generally have large surface area and/or porous structures and showed unique synergistic effects with CPs. Therefore, a stable, environmentally friendly bio/electro-catalyst can be obtained with CPNHs along with better catalytic activity and enhanced electron-transfer rate. The mass activity of Pd/polypyrrole (PPy) CPNHs as an anode material for ethanol oxidation is 7.5 and 78 times higher than that of commercial Pd/C and bulk Pd/PPy. The Pd rich multimetallic alloys incorporated on PPy nanofibers exhibited an excellent electrocatalytic activity which is approximately 5.5 times higher than monometallic counter parts. Similarly, binary and ternary Pt-rich electrocatalysts demonstrated superior catalytic activity for the methanol oxidation, and the catalytic activity of Pt24Pd26Au50/PPy significantly improved up to 12.5 A per mg Pt, which is approximately15 times higher than commercial Pt/C (0.85 A per mg Pt). The recent progress on CPNH materials as anode/cathode and membranes for fuel cell has been systematically reviewed, with detailed understandings into the characteristics, modifications, and performances of the electrode materials.