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

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 degrees 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. (C) 2011 Elsevier Inc. All rights reserved.