Pd-Shaped Nanoparticles Modified by Gold ad-Atoms: Effects on Surface Structure and Activity Toward Glucose Electrooxidation

Abstract

Palladium nanoparticles (Pd-NPs) with controlled distributions of sizes and shapes (nanospheres–Pd-NS-, nanocubes -Pd-NC-, and nanooctahedrons -Pd-NO-) are synthesized by wet chemistry methods and characterized by TEM/HRTEM. The surfaces of Pd-NPs are modified by spontaneous adsorption of gold and characterized by cyclic voltammetry in acidic medium. It is shown that the modification of Pd-NPs by dipping in HAuCl 4 solutions of different concentrations allows controlling the surface coverage by gold. It is also shown that the modification of Pd-NPs surfaces involves first the formation of PdAu surface alloys. For higher coverages, both PdAu surface alloys and pure Au structures are formed. The activity toward the glucose electrooxidation reaction is determined by linear scan voltammetry (LSV). Higher activity is observed on pure Pd-NC presenting extended (100) surfaces than on Pd-NO with mainly (111) surface orientation and on Pd-NS without preferential surface orientation, both these latter Pd-NPs displaying almost the same activity. The modification of the surface by spontaneous adsorption of gold greatly improves the activity of all Pd-NPs. However, Au-modified Pd-NC materials remain the most active catalysts. PdAu surface alloys seem to be involved in the improvement of the catalytic activity at low potentials, although the role of pure gold structures on Pd-NPs toward the enhancement of the catalytic activity cannot be excluded for high gold coverage. The study allows a better understanding of the material structure/electrocatalytic behavior relationship.

Recent Advances on Electrolysis for Simultaneous Generation of Valuable Chemicals at both Anode and Cathode

“…They can be also gained from glucose electro-oxidation, identifying and quantifying by HPLC. [70,71] As far as we know, it can be clearly found that the real catalytic active phase for glucose oxidation reaction (GOR) was metal oxidized species.…”

Electroreforming of Glucose and Xylose in Alkaline Medium at Carbon Supported Alloyed Pd3Au7 Nanocatalysts: Effect of Aldose Concentration and Electrolysis Cell Voltage

“…The coulombic charges in the reduction peaks allow determining the surface percentage of each structure and then determining the whole surface composition [25,27,41]. The surface of the Pd 3 Au 7 /C catalyst exhibits non-alloyed Au islands (56% of the surface) and two PdAu alloys with Pd/Au atomic compositions of 6/4 (36% of the surface) and 8/2 (8% of the surface) leading to a global surface composition of 28 at% Pd and 72 at% Au close to the bulk nominal one (30 at% Pd and 70 at% Au).…”

In Situ Investigation of d-Glucose Oxidation into Value-Added Products on Au, Pt, and Pd under Alkaline Conditions: A Comparative Study

“…Achieving a continuous process with good selectivity and specificity requires one to investigate the stability of the products obtained from glucose toward oxidation. At the positive electrode, electrooxidation of d -glucose to produce gluconic acid on various catalysts has been widely discussed. − Some authors investigated the effect of surface orientation on the catalyst activity for glucose oxidation. − It appeared that (100) surface domains were the most active ones for Au and Pd, whereas Pt(111) surface domains led to higher activity toward glucose oxidation. In comparison, few studies were carried out on gluconic acid oxidation. , Furthermore, as crossover of sorbitol (produced at the negative electrode) through the membrane cannot be excluded, its oxidation in the anode conditions has to be investigated equally. , …”