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 (Ea) for the ethanol electrooxidation reaction.

Rapid Aqueous Synthesis of Large-Size and Edge/Defect-Rich Porous Pd and Pd-Alloyed Nanomesh for Electrocatalytic Ethanol Oxidation.

In this work, a facile aqueous synthesis strategy was used (complete in 5 min at room temperature) to produce large-size Pd, PdCu, and PdPtCu nanomeshes without additional organic ligands or solvent and the volume restriction of reaction solution. The obtained metallic nanomeshes possess graphene-like morphology and a large size of dozens of microns. Abundant edges (coordinatively unsaturated sites, steps, and corners), defects (twins), and mesopores are seen in the metallic ultrathin structures. The formation mechanism for porous Pd nanomeshes disclosed that they undergo oriented attachment growth along the ⟨111⟩ direction. Owing to structural and compositional advantages, PdCu porous nanomeshes with certain elemental ratios (e. g., Pd87 Cu13 ) presented enhanced electrocatalytic performance (larger mass activity, better CO tolerance and stability) toward ethanol oxidation.

Highly branched and defect-rich PdP nanosheets for ethanol oxidation electrocatalysis.

Highly branched PdP nanosheets (NSs) rich in defects and with a thickness of ∼3.2 nm were synthesized, for the first time, via a nanoconfined attachment growth mechanism inside assembled lamellar micelles. Owing to the synergistic structural (being a highly branched, ultrathin, and defect-rich material) and compositional (P-alloyed) advantages, the PdP NSs exhibited remarkable electrocatalytic activity (3.2 A mgPd-1), a low reaction activation energy (16.0 kJ mol-1), good CO anti-poisoning ability, and electrocatalytic stability during the ethanol oxidation reaction (EOR) in alkaline conditions.