CN x -modified montmorillonite as support to immobilize Pd and its enhanced electrocatalytic activity for formic acid oxidation

Abstract

Nature clay, i.e., montmorillonite (MMT), can be used as support materials of anode electrocatalyst in the direct formic acid fuel cell. The nitrogen-containing composite support (MMT-CN x ) was prepared via carbonizing MMT which was covered by polyaniline. Pd/MMT-CN x and Pd/C catalysts were prepared as formic acid oxidation catalysts using an improved liquid reduction method. The composite, structure, surface properties, and electrical conductivity of the supports and catalysts were studied by energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electrochemical impedance spectroscopy (EIS). The results showed that welldispersed Pd nanoparticles with a narrow size distribution of 3.5-5.5 nm could be easily prepared on the MMT-CN x . Larger electrochemical specific area (ECSA) was obtained for Pd/ MMT-CN x than Pd/C according to CO-stripping voltammetry. Cyclic voltammetry (CV) and chronoamperometry (CA) measurements showed better catalytic activity and stability of the Pd/MMT-CN x catalyst than the conventional Pd/C catalyst for formic acid electrooxidation. Larger ECSA and doped nitrogen in the support of the Pd/MMT-CN x catalyst may be the main reason of higher activity and better stability for formic acid oxidation compared with the Pd/C catalyst. The results offered potential application of composite support (MMT-CN x ) for the catalyst of the direct formic acid fuel cell.

Optimized Synthesis of Nitrogen and Phosphorus Dual-Doped Coal-Based Carbon Fiber Supported Pd Catalyst with Enhanced Activities for Formic Acid Electrooxidation

“…They all exhibit two obvious peaks that appeared at around 1348 cm –1 (D band) and 1575 cm –1 (G band) of carbon materials, which is basically consistent with previous reports . The D band and G band are assigned to the structure of sp 3 and sp 2 of the carbon atom, corresponding to the disordered graphite and the graphitization on the surface of carbon materials . The intensity ratio of the D band and G band ( I D / I G ) can be used to evaluate the defects in carbon materials .…”

Application of biowaste and nature-inspired (nano)materials in fuel cells

“…287,288 For instance, a synthesized nitrogen-based composite, with MMT support and NC was employed in a DFAFC. 289 MMT-N x C was fabricated via the carbonization of MMT, covered with PANi, and then heating of MMT-PANi. The Pd/MMT-N x C catalysts displayed a uniform dispersion of Pd NPs and showed high catalytic activity for formic acid oxidation compared to traditional Pd/C catalysts.…”