Synthesizing alloyed bimetallic electrocatalysts with a three-dimensional (3D) structure assembly have arouse great interests in electrocatalysis. We synthesized a class of alloyed Pd3Pb/Pd nanosheet assemblies (NSAs) composed of a two-dimensional (2D) sheet structure with adjustable compositions via an oil bath approach at a low temperature. Both the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images reveal the successful formation of the nanosheet structure, where the morphology of Pd3Pb/Pd NSAs can be regulated by adjusting the atomic mole ratio of Pb and Pb metal precursors. The power X-ray diffraction (XRD) pattern shows that Pd3Pb/Pd NSA catalysts are homogeneously alloyed. Electrochemical analysis and the density functional theory (DFT) method demonstrate that the electrocatalytic activity of the alloyed Pd3Pb/Pd NSAs can be improved by the doping of the Pb element. As a result of the addition of element Pb and change of the electron structure, the electrocatalytic activity toward ethanol oxidation of alloyed Pd3Pb/Pd-15 NSA can reach up to 2886 mA mg–1, which is approximately 2.8 times that of the pure Pd NSA counterpart (1020 mA mg–1). The Pd3Pb/Pd NSAs are favorable in a high catalytic temperature, high KOH concentration, and high ethanol concentration.

The synthesis of metal nanometer electrocatalysts with a two-dimensional (2D) structure or rich active sites has become a research hotspot in electrocatalysis. In this work, surfactant hexadecyltrimethylammonium bromide (CTAB) was used to assist the synthesis and assembly of Pd ultrathin nanosheet with the help of Mo­(CO)6 in the start system. Pd nanochain composed of nanoparticles is obtained under the same condition, replacing CTAB with carrageenan only. Electrochemical measurements showed that the catalytic peak current density for the electrooxidation of ethanol can reach 2145 mA mg–1 for the Pd nanosheet assembly (NSA) and 1696 mA mg–1 for Pd nanochains. Pd nanosheet assembly also has a lower electron-transfer barrier, better catalytic stability, and antipoisoning performance than that of Pd nanochains. The mechanism of Pd nanosheets and nanochains catalysts the enhanced electrocatalytic activity toward ethanol oxidation has been discussed based on the experimental data.

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.

Atomically ordered intermetallic compounds (OICs) have aroused remarkable interests for wide applications and are considered as very promising materials for electrocatalysis owing to the strict stoichiometry, well-defined atom binding environment, and the specific crystalline phase. However, the tunable synthesis of the intermetallics remains a giant challenge. Herein, this study reports the preparation of the Pd-Sn OICs composed of an interconnected nanowire network structure with adjustable molar ratios of elements Pd and Sn. The co-reduction of Pd(acac) 2 and SnCl 2 •2H 2 O in ethylene glycol (EG) in the presence of sodium hypophosphite (NaH 2 PO 2 ) as the reducing agent affords OICs of three phases: hexagonal Pd 3 Sn 2 -P6 3 /mmc, orthorhombic PdSn-Pnmb, and orthorhombic PdSn 2 -Aba2. Also, the pure phase can convert to two mixed phases (Pd 3 Sn 2 /PdSn and PdSn/PdSn 2 ) by just altering the feed ratio. It is found that orthorhombic PdSn-Pnmb OIC has a large electrochemically active surface area (ECSA), excellent electrocatalytic performance (4857 mA mg Pd −1), and outstanding stability toward ethanol oxidation reaction (EOR), which could be attributed to its optimal electronic structure. These results demonstrate that the phase engineering of OICs with desired components is an excellent way for catalysts design.

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