Metal Bromide Controlled Interfacial Aromatization Reaction for Shape‐Selective Synthesis of Palladium Nanostructures with Efficient Catalytic Performances

Abstract

Herein, the effect of diverse metal bromides for the shape evolution of palladium nanostructures (Pd NS) has been demonstrated. Aromaticity-driven reduction of bromopalladate(II) is optimized to reproducibly obtain different Pd NS at the water/organic layer interface. In this soft interfacial strategy, a redox potential driven reaction has been performed, forming the thermodynamically more stable (>10(4) -fold) PdBr4 (2-) precursor from PdCl4 (2-) by adding extra metal bromides. In the process, the reductant, Hantzsch dihydropyridine ester (DHPE), is aromatized. Interestingly, alkali metal bromides devoid of coordination propensity exclusively evolve Pd nanowires (Pd NWs), whereas in the case of transition metal bromides the metal ions engage the 'N' donor of DHPE at the interface, making the redox reaction sluggish. Hence, controlled Pd nanoparticles growth is observed, which evolves Pd broccolis (Pd NBRs) and Pd nanorods (Pd NRs) at the interface in the presence of NiBr2 and CuBr2 , respectively, in the aqueous solution. Thus, the effect of diverse metal bromides in the reaction mixture for tailor-made growth of the various Pd NS is reported. Among the as-synthesized materials, the Pd NWs stand to be superior catalysts and their efficiency is almost 6 and 2.5 times higher than commercial 20 % Pd/C in the electrooxidation of ethanol and Cr(VI) reduction reaction by formic acid, respectively.

Biomass Derived Sheet-like Carbon/Palladium Nanocomposite: An Excellent Opportunity for Reduction of Toxic Hexavalent Chromium

“…This is done by monitoring the UV–vis absorption spectra of K 2 Cr 2 O 7 (0.8 mM) and FA (0.45 M) in aqueous solution over varied experimental parameters such as amount of catalyst, reaction temperature, and reaction time. Owing to the ligand to metal charge-transfer transition, potassium dichromate (K 2 Cr 2 O 7 ) exhibits only a strong absorption peak at λ max = 350 nm. , However, as shown in Figure S5 (SI), a null reduction of Cr­(VI) was observed without a catalyst, even in the presence of FA. Thus, the catalytic property of the catalyst is crucial for efficient reduction of Cr­(VI).…”

“…Owing to the ligand to metal charge-transfer transition, potassium dichromate (K 2 Cr 2 O 7 ) exhibits only a strong absorption peak at λ max = 350 nm. 46,47 However, as shown in Figure S5 (SI), a null reduction of Cr(VI) was observed without a catalyst, even in the presence of FA. Thus, the catalytic property of the catalyst is crucial for efficient reduction of Cr(VI).…”

Subchronic exposure to palladium nanoparticles affects serum levels of cytokines in female Wistar rats

“…1 Moreover, several palladium (Pd)-based nanostructures with different morphologies have been increasingly synthesized and used in catalytic and electrocatalytic chemical reactions, wastewater treatment, jewelry, electronics, and in biomedical fields. [2][3][4] Furthermore, modern three-way automobile catalytic converters (containing Pd) 5,6 can cause the release and the accumulation of Pd ultrafine particles (PdUFPs) in several environmental matrices. [7][8][9] Therefore, considering that both Pd nanoparticles (PdNPs) and PdUFPs are characterized by particular physicochemical features that may make their properties more harmful than those of larger particles of the same material, 10 it seems vital to understand the risks that the probable increase in exposure to nano-sized Pd particles may pose to human safety and health.…”