Metal-Free and Pt-Decorated Graphene-Based Catalysts for Hydrogen Production in a Sulfur–Iodine Thermochemical Cycle

Abstract

Graphene oxide (GO), GO reduced by hydrazine hydrate (rGO-HH), GO reduced by ethylene glycol (rGO-EG), Pt-decorated rGO-HH composite (Pt/rGO-HH), and Pt-decorated rGO-EG composite (Pt/rGO-EG), are fabricated for the heterogeneous catalytic decomposition of HI in a sulfur–iodine thermochemical cycle. Corresponding material characterization on various catalysts are performed to gain insight into the catalytic mechanism. rGO-HH presents better catalytic activity than the GO and rGO-EG counterparts, due to the increase of active sites (unsaturated carbon atoms) with the reduction of oxygen-containing groups and the formation of edge planes. Homogeneously dispersed fine Pt nanoparticles are obtained with employing rGO-EG as the support. The corrugation morphology and graphene edges benefit the nucleation, dispersion, and immobilization of Pt nanoparticles. As a consequence, Pt/rGO-EG presents better catalytic activity and stability than the convenient Pt/activated-carbon (Pt/AC) counterpart. Results indicate t...