Reaction of Co₃O₄ Nanocrystals on Graphene Sheets to Fabricate Excellent Catalysts for Hydrogen Generation

The development of functionalized graphene is of significant importance for the application of graphene in solving current energy and environmental problems. In this work, a series of graphene-based hybrid materials including porous graphene (PG) and carbon nanofibers anchored graphene oxide (GCNFs) were synthesized adopting a controllable solid-phase reaction strategy. Co₃O₄ nanocrystals (NCs) were used as oxidants to modify and adjust graphene sheets. The PG and GCNFs were formed crucially through the red-ox reaction between graphene and Co₃O₄ NCs during calcinations. As catalyst for NaBH₄ hydrolysis at room temperature, CoO_<i>x</i> NCs anchored onto PG and CoO_<i>x</i> NCs anchored onto GCNFs provided hydrogen generation specific rates of 1472 mL·min^–1·g_Co^–1 and 2696 mL·min^–1·g_Co^–1, respectively. These outstanding catalytic activities are attributed to the synergistic effect of CoO_<i>x</i> NCs and PG/GCNFs. A general strategy was proposed for the oxidative cutting and reconstruction of graphene sheets, and the preparation of high active catalysts for hydrogen generation from NaBH₄ hydrolysis