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Structure-controlled synthesis of Pd nanocrystals has received much attention recently due to their remarkable catalytic performance. To get deep insight into the mechanism of kinetically controlled overgrowth and the relationship between structure and electrocatalytic performance, palladium concave nanocubes (PdCNs) with high-index facets were synthesized through a facile none-seeded routine induced by hexadecylpyridinium bromide (CTAB). The structural changes of PdCNs along with the concentration of CTAB, reaction time and temperature were investigated by transmission electron microscopy and X-ray diffraction. It was indicated that Pd nanocubes first grew into larger size with numerous interstices inside the PdCNs, and then the inner interstices were filled along with oxidative etching on the surface. The electrocatalytic activities of PdCNs with different structures were evaluated toward the electro-oxidation of methanol. The result showed that the electrocatalytic activity weakened with the decrease in interstices, which demonstrated that interstices played a more crucial role than the concave structures. [ABSTRACT FROM AUTHOR]

Palladium nanoparticles with a uniform shape and specific surface structure have gained tremendous attention owing to their fascinating catalytic performance. Herein, Pd porous nanocubes (PdPNs) were successfully synthesized through a facile one-pot non-seeded routine using 1-hexadecyl-3-methyl imidazolium bromide (HMIB) as the capping agent. The as-prepared PdPNs had a cubic shape and highly porous feature with an average size of 45.4 nm. The morphology evolution along with time was investigated by transmission electron microscopy and a possible formation mechanism of PdPNs was proposed. The effects of the concentration of HMIB and temperature on the structure and electrocatalytic activity were also investigated. The PdPNs showed superior catalytic activity (jf = 13.11 mA cm−2) in methanol electro-oxidation in an alkaline medium to solid Pd nanocubes (jf = 7.25 mA cm−2) and a commercial Pd/C catalyst (jf = 0.11 mA cm−2). Meanwhile, PdPNs exhibited excellent stability, which was inferred from the current density remaining at 86.3% of the initial value after 1500 cycles. [ABSTRACT FROM AUTHOR]

Structure‐controlled synthesis of palladium nanoparticles has long been a hot subject because of their remarkable catalytic performance. Herein, hexadecylpyridinium bromide (HDPB) was introduced as capping agent in the preparation of Pd nanoparticles (PdNPs) through a facile none‐seeded routine using Na2PdCl4 as precursor. The as‐prepared PdNPs was in the shape of flocculus and it had a highly porous feature with an average size of 53.1 nm. The morphology evolution along with time was investigated by transmission electron microscopy and a possible formation mechanism of PdNPs was proposed. Meanwhile, the structural changes of PdNPs along with the concentration of HDPB and temperature were also studied. The relationship between structure and electrocatalytic activity were discussed. The electrocatalytic performance of PdNPs was much superior than commercial Pd/C toward methanol electro‐oxidation in the alkaline medium. The optimum electrocatalytic activity (jf=19.4 mA cm−2) was obtained catalyzing by PdNPs synthesized when n(HDPB)/n(Pd2+)=0.6 : 1 at 50°C for 3 h. [ABSTRACT FROM AUTHOR]

The bio‐synthesis of palladium nanocubes (PdNCs) was realised using pine needle extract as the reducing agent and cetyl trimethyl ammonium bromide as the capping agent. As an eco‐friendly and readily available biomass, pine needle extract avoided the use of highly polluting chemical reducing agents. The growth process of PdNCs was analysed using ultraviolet–vis and Fourier transform infrared spectroscopy. Flavonoids, esters, terpenoids and polyhydric alcohols, which contain reductive groups, were mainly responsible for the transition of Pd2+ ions to PdNCs. The morphology and structure of PdNCs were characterised using transmission electron microscopy (TEM), high‐resolution TEM, selected area electron diffraction and X‐ray diffraction. It was indicated that the as‐prepared PdNCs displayed a relatively high purity and good crystallinity with a face‐centred cubic structure and exhibited sizes ranging from 6.11 to 29.51 nm with an average particle size of 11.18 nm. In the methanol electro‐oxidation reaction, the PdNCs enclosed by {100} facets exhibited superior electro‐catalytic activity to commercial Pd/C, which was rarely reported in other bio‐synthesis processes for Pd catalysts. Meanwhile, the PdNCs showed excellent anti‐poisoning ability and long‐term stability. This study reveals the possibility of preparing shape‐controlled PdNCs with a specific structure and excellent electro‐catalytic activity. [ABSTRACT FROM AUTHOR]