Characterisation and hydrogen storage of Pt-doped carbons templated by Pt-exchanged zeolite Y

Abstract

The successful insertion, via a simple ion exchange route, of Pt nanoparticles into the porosity of zeolite-templated carbon (ZTC) materials is demonstrated. Pt doping has been achieved via Pt ion exchange into zeolite Y prior to its use as a template. TEM images reveal that Pt nanoparticles are homogeneously dispersed in the ZTC matrix and that smaller (3–5 nm), more uniform particles with better distribution are obtained via the ion exchange route compared to when doping is performed using conventional methods such as post-synthesis incipient wetness impregnation of Pt onto already formed ZTCs. The Pt-exchanged ZTCs have high surface area (1400–2200 m 2/g), high micropore surface area (1200–1900 m 2/g), large pore volume (0.8–1.20 cm 3/g) and exhibit pore ordering replicated from the zeolite Y template. The Pt-exchanged ZTCs store between 3 and 5 wt.% hydrogen at −196 °C and 20 bar, and the amount of hydrogen adsorbed correlates well with the textural characteristics of the carbons. However, the Pt-exchanged ZTCs exhibit higher hydrogen storage capacity per unit surface area and higher isosteric heat of adsorption (9 kJ mol −1) than Pt impregnated ZTC prepared via incipient wetness (7.8 kJ mol −1). Our findings show that the ion exchange method is attractive as an alternative metal-doping route to the commonly used incipient wetness impregnation process.