Cu2+-regulated one-pot wet-chemical synthesis of uniform PdCu nanostars for electrocatalytic oxidation of ethylene glycol and glycerol

The fabrication of effective and stable electrocatalysts is crucial for practical applications of direct alcohol fuel cells (DAFCs). In this study, bimetallic PdCu nanostars (PdCu NSs) were fabricated by a Cu²⁺-modulated one-pot wet-chemical method, where cetyltrimethyl ammonium bromide (CTAB) worked as a structure-regulating reagent. The morphology, compositions, crystal structures and formation mechanism of the as-prepared PdCu NSs were investigated by a series of techniques. The unique architectures created abundant active sites, which resulted in a large electrochemical active surface area (9.5 m² g^-1). The PdCu NSs showed negative shifts in the onset potentials and large forward peak current densities by contrast with those of commercial Pd black for the catalytic ethylene glycol oxidation reaction (EGOR) and glycerol oxidation reaction (GOR). It revealed that the PdCu NSs outperformed Pd black in the similar surroundings. This work provides a constructive strategy for fabrication of high-efficiency electrocatalysts for alcohol fuel cells.

Cyanogel-Induced Synthesis of RuPd Alloy Networks for High-Efficiency Formic Acid Oxidation

For direct formic acid fuel cells (DFAFC), palladium (Pd)-based alloy catalysts with competitive morphology and elemental composition are essential to boost the performance of the formic acid oxidation reaction (FAOR) in the anode zone. Herein, we design and synthesize RuPdx alloy nano-network structures (ANs) via the facile wet-chemical reduction of Pd-Ru cyanogel (Pdx [Ru(CN)6]y·aH2O) as an effective electrocatalyst for the FAOR. The formation of Pd-Ru cyanogel depends on the facile coordination of K2PdCl4 and K3 [Ru(CN)6]. The unique structure of cyanogel ensures the presentation of a three-dimensional mesoporous morphology and the homogeneity of the elemental components. The as-prepared RuPd3 ANs exhibit good electrocatalytic activity and stability for the FAOR. Notably, the RuPd3 ANs achieve a mass-specific activity of 2068.4 mA mg−1 in FAOR, which shows an improvement of approximately 16.9 times compared to Pd black. Such a competitive FAOR performance of RuPd3 ANs can be attributed to the advantages of structure and composition, which facilitate the exposure of more active sites, accelerate mass/electron transfer rates, and promote gas escape from the catalyst layer, as well as enhance chemical stability.

Propitious Dendritic Cu2O-Pt Nanostructured Anodes for Direct Formic Acid Fuel Cells

This study introduces a novel competent dendritic copper oxide-platinum nanocatalyst (nano-Cu₂O-Pt) immobilized onto a glassy carbon (GC) substrate for formic acid (FA) electro-oxidation (FAO); the prime reaction in the anodic compartment of direct formic acid fuel cells (DFAFCs). Interestingly, the proposed catalyst exhibited an outstanding improvement for FAO compared to the traditional platinum nanoparticles (nano-Pt) modified GC (nano-Pt/GC) catalyst. This was evaluated from steering the reaction mechanism toward the desired direct route producing carbon dioxide (CO₂); consistently with mitigating the other undesired indirect pathway producing carbon monoxide (CO); the potential poison deteriorating the catalytic activity of typical Pt-based catalysts. Moreover, the developed catalyst showed a reasonable long-term catalytic stability along with a significant lowering in onset potential of direct FAO that ultimately reduces the polarization and amplifies the fuel cell's voltage. The observed catalytic enhancement was believed to originate bifunctionally; while nano-Pt represented the base for the FA adsorption, nanostructured copper oxide (nano-Cu₂O) behaved as a catalytic mediator facilitating the charge transfer during FAO and providing the oxygen atmosphere inspiring the poison's (CO) oxidation at relatively lower potential. Surprisingly, moreover, nano-Cu₂O induced a surface retrieval of nano-Pt active sites by capturing the poisoning CO via "a spillover mechanism" to renovate the Pt surface for the direct FAO. Finally, the catalytic tolerance of the developed catalyst toward halides' poisoning was discussed.