Bimetallic Face-Centered Cubic Pd–Ag Nano-dendritic Alloys Catalysts Boost Ethanol Electrooxidation

Abstract

The development of green and sustainable energy is important for the current society to address global climate change. Direct ethanol fuel cells have attracted extensive attention at home and abroad due to their environmentally friendly features, high energy density, and ease of management. Herein, a class of alloyed PdAg catalysts with a controllable alloying degree as well as lattice expansion were prepared. The PdAg nano-dendritic alloys (NDAs) exhibit “volcano-type” behavior, where the Pd5Ag1 NDA with a tensile value of 1.0% possesses the highest peak current density (1950 mA mg–1) for ethanol oxidation reaction (EOR), controlled by a dynamic balance of active and blocking species adsorption energy. This electrocatalytic behavior mainly arises from the formation of a crystalline nano-dendritic structure and the synergistic effect between Pd and Ag. Moreover, the kinetics of EOR determined that higher electrocatalytic temperatures and higher concentrations of OH– or C2H5OH are favorable for EOR.

Assembly of Alloyed PdM (Ag, Cu, and Sn) Nanosheets and Their Electrocatalytic Oxidation of Ethanol and Methanol

“…As depicted in Figure a, characteristic diffraction peaks of three samples can be observed at 40.1, 46.6, 68.1, and 82.1° in the XRD patterns, which correspond to the crystallographic planes (111), (200), (220), and (311) of Pd [JCPDS No. 46-1043], respectively . Due to the different atomic radii of the second metal, when introduced into the fcc crystal of Pd, different lattice changes are induced. , As depicted in Figure b, the enlarged XRD patterns show the shift of the characteristic diffraction peaks occurring near the (111) crystal plane for the bimetallic alloy.…”

“…46-1043], respectively. 45 Due to the different atomic radii of the second metal, when introduced into the fcc crystal of Pd, different lattice changes are induced. 46,53 As depicted in Figure 2b, the enlarged XRD patterns show the shift of the characteristic diffraction peaks occurring near the (111) crystal plane for the bimetallic alloy.…”

“…Numerous products can be generated, such as incompletely oxidized acetaldehyde with acetic acid. Under alkaline conditions, the electro-oxidation reactions of ethanol may include: ,, CH 3 CH 2 OH + 2OH − → CH 3 CHO + 2H 2 normalO + 2e − CH 3 CH 2 OH + 5OH − → CH 3 COO − + 4H 2 normalO + 4e − CH 3 CH 2 OH + 16 OH − → 2CO 3 2 − + 11 normalH 2 normalO + 12 normale − …”

Thermally Stable AgPd@ZnO Bimetallic Alloy Nanoparticles for Ethanol Sensors with Long-Term Stability

“…Additionally, because of their excellent catalytic activity, high electronic effect, and superior stability, Ag–Pd bimetallic alloy NPs seem to be the most attractive and extensively studied in various catalytic fields. − It is believed that preparing bimetallic alloy Ag–Pd alloy NP catalysts would maximize selectivity due to the presence of Ag and would increase Pd’s atom economy . Alloy NPs based on AgPd have been shown to have outstanding catalytic performance and operational stability for the alcohol oxidation. , This is due to the modulation of their electronic structure and the effect of crystalline deformation. , …”

“…20,21 This is due to the modulation of their electronic structure and the effect of crystalline deformation. 22,23 Because of the high surface energy of noble metal NPs, they tend to aggregate quickly at higher operating temperatures, limiting their long-term stability. Wang et al investigated the long-term stability of the H 2 sensor of the bimetallic Pd−Ag alloy nanocatalyst on the ZnO surface by gas-cell in situ transmission electron microscopy (TEM) at higher operating temperature (300 and 500 °C).…”