Microwave plasma assisted preparation of Pd-nanoparticles with controlled dispersion on woven activated carbon fibres

Abstract

The low-pressure cold microwave (MW) plasma is shown as an efficient method to increase acidity of the ACF within less than 1 min treatment without affecting the fibre morphology and strength. The ion-exchange capacity was 1.6 times higher compared to the non-treated ACF sample. Selective removal of the carboxylic groups from the ACF surface by the air-MW-plasma allows to keep the phenolic groups intact. Palladium was deposited on ACF from [Pd(NH 3 ) 4 ]Cl 2 solution via ion-exchange with the protons of the phenolic surface groups. Surface phenolic groups were able to chemically anchor Pd in cationic form, leading after reduction in H 2 to small Pd8 nanoparticles (<3 nm). The Pd dispersion was measured by CO pulse adsorption and confirmed by the TEM analysis. Heating of the Pd/ACF catalysts in H 2 at 573-773 K is necessary to reduce Pd(II) to Pd8. This reduction can be also achieved by the H 2 -MW-plasma treatment in less than 1 min with the corresponding saving of energy. #

Enhanced electrocatalytic activity of CoTMPP-based catalysts for PEMFCs by plasma treatment

“…Low temperature plasma has been extensively utilized in catalysis, including plasma-assisted synthesis of catalytic active ultra-fine particles and their deposition on support, plasma regeneration or plasma treatment of catalysts [31][32][33][34][35][36][37]. Most of the conventional methods for preparation of catalysts include high-temperature calcinations/reduction or pyrolysis in an inert atmosphere.…”

A Combined Experimental and Theoretical Investigation of Atomic-Scale Defects Produced on Graphite Surfaces by Dielectric Barrier Discharge Plasma Treatment

“…These include first-wall materials for nuclear reactors, − re-entry shields of spacecraft, biomedical materials, − anodes for fuel cells , and Li-ion batteries, or catalyst supports. , Among the existing methods for the surface modification of carbon materials (e.g., bombardment with high and low , energy ions, high temperature oxidation, or wet chemical and electrochemical oxidation), surface modification by plasmas is particularly attractive owing to a number of advantageous features: it is a nonpolluting, potentially scalable process, the modification is strictly restricted to the surface of the material without affecting its bulk properties, the treatments are relatively easy to control, and different chemical species can be readily obtained just by changing a few processing parameters . In particular, plasma oxidation (i.e., plasma treatment under oxygen-containing gases) is widely employed to control such properties as adhesion, molecular adsorption, wettabilitty, or surface porosity. − …”

Multiscale Imaging and Tip-Scratch Studies Reveal Insight into the Plasma Oxidation of Graphite

“…28 As various recent examples demonstrate, plasma oxidation is a useful approach to enhance and/or fine-tune the surface properties not only of graphite 11,16 but also of other sp 2 -based carbon materials of interest, such as carbon nanotubes [29][30][31] and activated carbon fibers. [32][33][34] Nonetheless, our current understanding of the plasma oxidation process of carbon materials is still relatively limited compared to the other types of oxidation. Previous studies on graphite have mostly established the main morphological changes on the micrometer and nanometer scales induced by oxygen plasma exposure.…”