Solvent effects on the structural and catalytic properties of Pt nano- and microstructures synthesised in solvothermal system

摘要

Platinum (Pt) nanoand microstructures were synthesised in different types of solvent (e.g. water (H2O), dimethylformamide (DMF), monoethanolamine (MEA) and a mixture of H2O and DMF) by using solvothermal technique. Spherical particles of diameter ranging from 80 nm to 230 nm were formed when prepared in H2O, whereas particles with irregular shapes were produced from the H2O/DMF media. Particles with flower-like structures of diameter ranging from 140 nm to 200 nm were produced by using DMF solvent, while cubic microstructures with sizes of about 0.7 mm-1.0 mm were formed in the MEA media. The crystallinity of Pt particles prepared in different media increased, following the trend of H2O H2O/DMF MEA DMF. The flower-like Pt structures exhibited a high catalytic performance towards the oxidation of formic acid, as demonstrated by the high electroactive surface area of 0.4058 m(2), which was better than Pt black in terms of resistance towards CO poisoning, and showed high stability with current density of 0.41 mA/cm(2) for 1000 s. The Pt particles synthesised in MEA exhibited small electroactive area, but more resistance towards CO poisoning as compared to sample prepared in H2O. Therefore, this showed that the catalytic properties of Pt are highly dependent on the faceted structures, whereby large number of edges and corners increased the surface-to-volume ratio, and thus the absorption sites for electrooxidation of formic acid. (c) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.