Two-dimensional template-directed synthesis of one-dimensional kink-rich Pd3Pb nanowires for efficient oxygen reduction

Developing facile synthetic strategies toward ultrafine one-dimensional (1D) nanowires (NWs) with rich catalytic hot spots is pivotal for exploring effective heterogeneous catalysts. Herein, we demonstrate a two-dimensional (2D) template-directed strategy for synthesizing 1D kink-rich Pd₃Pb NWs with abundant grain boundaries to serve as high-efficiency electrocatalysts toward oxygen reduction reaction (ORR). In this one-pot synthesis, ultrathin Pd nanosheets were initially generated, which then served as self-sacrificial 2D nano-templates. A dynamic equilibrium growth was subsequently established on the 2D Pd nanosheets through the center-selected etching of Pd atoms and edge-preferred co-deposition of Pd/Pb atoms. This was followed by the oriented attachment of the generated Pd/Pb alloy nanograins and fragments. Thus, kink-rich Pd₃Pb NWs with rich grain boundary defects were obtained in high yield, and these NWs were used as electrocatalytic active catalysts. The surface electronic interaction between Pd and Pb atoms effectively decreased the surface d-band center to weaken the binding of oxygen-containing intermediates toward improved ORR kinetics. Specifically, the kink-rich Pd₃Pb NWs/C catalyst delivered outstanding ORR mass activity and specific activity (2.26 A⋅mg_Pd^-1 and 2.59 mA⋅cm^-2, respectively) in an alkaline solution. These values were respectively 13.3 and 10.8 times those of state-of-the-art commercial Pt/C catalyst. This study provides an innovative strategy for fabricating defect-rich low-dimensional nanocatalysts for efficient energy conversion catalysis.

Engineering ultrathin PdAu nanoring via a facile process for electrocatalytic ethanol oxidation

Ultrathin nanoframes with more available electrocatalytic active sites on both internal and external surfaces have attracted great attention especially in the field of electrocatalysis. Herein, we report a facile process to prepare PdAu nanorings (NRs) in aqueous solution without adding any organic ligands. The growth mechanism of PdAu NRs was explored in detail. The Au precursors were reduced into Au clusters around the edges of Pd nanosheets (NSs) via galvanic replacement, then the center of Pd NSs was oxidatively etched by Cl^-/O₂, and finally the Pd and Au atoms on the edge sites were rearranged to form uniform PdAu alloy. PdAu NRs with different ratios and ternary PdAuPt NRs could be easily prepared using this strategy. Owing to the synergistically structural and compositional advantages, Pd₇₉Au₂₁ NRs exhibited higher electrocatalytic activity and stability, as well as low activation energy (E_a) for the ethanol electrooxidation reaction.

Two-dimensional multimetallic alloy nanocrystals: recent progress and challenges

In this highlight article, the recent progress on the preparation and application of multimetallic alloy nanocrystals with 2D nanostructures is systematically reviewed, as well as perspectives on future challenges and opportunities.