Selective electrocatalytic hydrogenation using palladium nanoparticles electrochemically formed in layer-by-layer...

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Layer-by-layer (LbL) self-assembly is a versatile technique for creating functional thin films.
• Palladium nanoparticles (Pd-NPs) are effective electrocatalysts for hydrogenation reactions.

Purpose of the Study:

• To synthesize Pd-NPs within polyelectrolyte multilayers via sequential adsorption and electrochemical reduction.
• To investigate the electrocatalytic hydrogenation (ECH) of acetophenone and benzophenone using Pd-NPs of varying sizes.
• To understand the influence of Pd-NP size and polyelectrolyte multilayers on reaction product distribution and faradaic yield.

Main Methods:

• Sequential adsorption of PdCl4(2-) onto weak polyelectrolyte multilayer films.
• Electrochemical reduction to form Pd(0) nanoparticles (Pd-NPs).
• Electrocatalytic hydrogenation of model molecules (acetophenone, benzophenone) in hydroalcoholic acid solution.
• Analysis of reaction products (secondary alcohols, alkanes) and faradaic yield.

Main Results:

• Polyelectrolyte multilayers confined PdCl4(2-) ions, preventing large crystal formation and acting as nanoreactors.
• ECH of acetophenone and benzophenone was performed on Pd-NPs ranging from 6 to 35 nm.
• The size of Pd-NPs influenced the selectivity towards secondary alcohols and alkanes, as well as the faradaic yield.
• Heat-treated surfaces, free from polyelectrolyte influence, isolated the effect of nanocrystal size on reaction outcomes.

Conclusions:

• LbL assembly provides a method for controlled synthesis of Pd-NPs for electrocatalysis.
• Nanoreactor effects of polyelectrolyte multilayers influence catalytic performance.
• Pd-NP size is a critical factor determining selectivity and efficiency in ECH reactions.