Synergistic Effect of Tungsten Carbide and Palladium on Graphene for Promoted Ethanol Electrooxidation

Abstract

The synergistic effect of WC and Pd has large benefit for ethanol electrooxidation. The small-sized Pd nanoparticles (NPs) decorated tungsten carbide on graphene (Pd-WC/GN) will be a promising anode catalyst for the direct ethanol fuel cells. The density functional theory (DFT) calculations reveal that the strong interaction exists at the interface between Pd and WC, which induces the electron transfer from WC to Pd. Fortunately, the nanoscale architecture of Pd-WC/GN has been successfully fabricated in our experiments. X-ray photoelectron spectrum further confirms the existence of electron transfer from WC to Pd in a Pd-WC/GN nanohybrid. Notably, electrochemical tests show that the Pd-WC/GN catalyst exhibits low onset potential, a large electrochemical surface area, high activity, and stability for ethanol electrooxidation in alkaline solution compared with Pd/graphene and Pd/commercial Vulcan 72R carbon catalysts. The enhancement can be attributed to the synergistic effect of Pd and WC on graphene. At the interface between Pd and WC, the electron transfer from WC to Pd leads to the increased electron densities of surface Pd, which is available for weakening adsorption of intermediate oxygen-containing species such as CO and activating catalyst. Meanwhile, the increased tungsten oxide induced by electron transfer can facilitate the effective removal of intermediate species adsorbed on the Pd surface through a bifunctional mechanism or hydrogen spillover effect.

Hydrothermal Method Using DMF as a Reducing Agent for the Fabrication of PdAg Nanochain Catalysts towards Ethanol Electrooxidation

“…The reduction peak of the PdAg catalyst was higher and shifted to negative potential compared with the pure Pd and commercial Pd/C catalysts, which may be ascribed to the simultaneous reduction of PdO and Ag oxides. The electrochemical surface area (ECSA) is usually applied to assess the electrochemical active sites of the catalysts, which can be deduced to be 402.1 cm 2¨m g´1, 328.2 cm 2¨m g´1 and 241.8 cm 2¨m g´1 according to the following Equation (1) [27,28]:…”

Hollow Sodium Nickel Fluoride Nanocubes Deposited MWCNT as An Efficient Electrocatalyst for Urea Oxidation

“…This might be due to the sharp decrease in oxygen content and an increase of F content on the SNF material surface. Due to the difference in electronegativity of the elements (Ni (1.9) and F (4.0)), a shift of electron density from Ni to F occurred, leading to a decrease in the shielding effect of outer electrons constraining the force of nuclear charge, thus enhancing the attraction of 2p electrons to the nucleus [41,42]. Thus, the XPS peaks in Ni 2p3/2 spectra showed a positive shift in binding energy.…”

An Effective Pt-Cu/SiO2 Catalyst for the Selective Hydrogenation of Cinnamaldehyde

“…This shift should be attributed to the electrons transfer from Cu to Pt by their intimate contact. In other studies [10,11,22,23,28], this electron transfer phenomenon between precious and promoter was also found, and the direction of this transfer changed with the nature of precious metal and promoter.…”