Chemical Design of Palladium-Based Nanoarchitectures for Catalytic Applications

Palladium (Pd) plays an important role in numerous catalytic reactions, such as methanol and ethanol oxidation, oxygen reduction, hydrogenation, coupling reactions, and carbon monoxide oxidation. Creating Pd-based nanoarchitectures with increased active surface sites, higher density of low-coordinated atoms, and maximized surface coverage for the reactants is important. To address the limitations of pure Pd, various Pd-based nanoarchitectures, including alloys, intermetallics, and supported Pd nanomaterials, have been fabricated by combining Pd with other elements with similar or higher catalytic activity for many catalytic reactions. Herein, recent advances in the preparation of Pd-based nanoarchitectures through solution-phase chemical reduction and electrochemical deposition methods are summarized. Finally, the trend and future outlook in the development of Pd nanocatalysts toward practical catalytic applications are discussed.

One-pot synthesis of bimetallic PdCu nanoframes as an efficient catalyst for the methanol oxidation reaction

A one-pot method is developed for the synthesis of PdCu nanoframes which are an active catalyst for the methanol oxidation reaction.

Real-time analysis of Pd2(dba)3 activation by phosphine ligands

Real-time UV-Vis/ESI-MS monitoring of Pd₂(dba)₃ activation provides insight into active species and the effect of activation protocol on their formation.

Preparation and enhanced electrocatalytic activity of graphene supported palladium nanoparticles with multi-edges and corners

Pd nanoparticles with multi-edges and corners are prepared and assembled on reduced graphene oxide to examine the electrocatalytic activity. Point discharge is regarded to be capable of facilitating the electron transfer.

Fullerene-ionic-liquid conjugates: a new class of hybrid materials with unprecedented properties

A modular approach has been followed for the synthesis of a series of fullerene-ionic-liquid (IL) hybrids in which the number of IL moieties (two or twelve), anion, and cation have been varied. The combination of C60 and IL give rise to new unique properties in the conjugates such as solubility in water, which was higher than 800 mg mL(-1) in several cases. In addition, one of the C60 -IL hybrids has been employed for the immobilization of palladium nanoparticles through ion exchange followed by reduction with sodium borohydride. Surprisingly, during the reduction several carbon nanostructures were formed that comprised nano-onions and nanocages with few-layer graphene sidewalls, which have been characterized by means of thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy/energy-dispersive X-ray analysis (SEM-EDAX), and high-resolution transmission electron microscopy (HRTEM). Finally, the material thus obtained was successfully applied as catalyst in Suzuki and Mizoroki-Heck reactions in a concentration of just 0.2 mol %. In the former process it was recyclable for five runs with no loss in activity.

Hierarchically structured catalyst layer for the oxygen reduction reaction fabricated by electrodeposition of platinum on carbon nanotube coated carbon fiber

Hierarchically structured fuel cell cathode catalysts consisting of Pt-nanoparticle clusters coated on a CNT-based, ORR active catalyst support were synthesized.

Facile green synthesis of palladium quantum dots@carbon on mixed valence cerium oxide/graphene hybrid nanostructured bifunctional catalyst for electrocatalysis of alcohol and water

Electrocatalytic oxidation of ethylene glycol at Pd quantum dots@C–CeOx/RGO electrode.

Synchronized synthesis of Pd@C-RGO carbocatalyst for improved anode and cathode performance for direct ethylene glycol fuel cell

The simultaneous formation of a carbocatalyst composed of 5 nm sized flower-shaped Pd nanoparticles assembled on carbon–reduced graphene oxide (Pd@C-RGO) is reported via the solid state process between 1 and 2 minutes followed by microwave irradiation and exhibits improved electrocatalytic performance for the oxidation of ethylene glycol.

Synthesis of palladium/helical carbon nanofiber hybrid nanostructures and their application for hydrogen peroxide and glucose detection

We report on a novel sensing platform for H2O2 and glucose based on immobilization of palladium-helical carbon nanofiber (Pd-HCNF) hybrid nanostructures and glucose oxidase (GOx) with Nafion on a glassy carbon electrode (GCE). HCNFs were synthesized by a chemical vapor deposition process on a C60-supported Pd catalyst. Pd-HCNF nanocomposites were prepared by a one-step reduction free method in dimethylformamide (DMF). The prepared materials were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy. The Nafion/Pd-HCNF/GCE sensor exhibits excellent electrocatalytic sensitivity toward H2O2 (315 mA M(-1) cm(-2)) as probed by cyclic voltammetry (CV) and chronoamperometry. We show that Pd-HCNF-modified electrodes significantly reduce the overpotential and enhance the electron transfer rate. A linear range from 5.0 μM to 2.1 mM with a detection limit of 3.0 μM (based on the S/N = 3) and good reproducibility were obtained. Furthermore, a sensing platform for glucose was prepared by immobilizing the Pd-HCNFs and glucose oxidase (GOx) with Nafion on a glassy carbon electrode. The resulting biosensor exhibits a good response to glucose with a wide linear range (0.06-6.0 mM) with a detection limit of 0.03 mM and a sensitivity of 13 mA M(-1) cm(-2). We show that small size and homogeneous distribution of the Pd nanoparticles in combination with good conductivity and large surface area of the HCNFs lead to a H2O2 and glucose sensing platform that performs in the top range of the herein reported sensor platforms.