Exfoliated Single Layers of Layered Cobalt Hydroxide for Ultrafine Co3O4 Nanoparticles on Graphene Nanosheets as an Efficient Electrocatalyst for Oxygen Reduction
Graphical Abstract
Sheet decoration: Self-assembly of exfoliated single-layer nanosheets of Co(OH)2 with graphene oxide (GO) followed by reduction and high-temperature calcination produced ultrafine, crystalline nanoparticles of spinel Co3O4 decorated on reduced GO (RGO) for use as an efficient electrocatalyst for the oxygen reduction reaction (ORR). The hybrid electrocatalyst exhibits comparable ORR activity to and more durable performance than commercial Pt/C catalyst because of the covalent coupling between uniformly decorated Co3O4 nanocrystals and the porous RGO layer.
Abstract
A highly effective way to produce an oxygen reduction electrocatalyst was developed through the self-assembly of exfoliated single layers of cobalt hydroxide (Co(OH)2) and graphene oxide (GO). These 2D materials have complete contact with one another because of their physical flexibility and the electrostatic attraction between negatively charged GO and positively charged Co(OH)2 layers. The strong coupling induces transformation of the Co(OH)2 single layer into a discrete nanocrystal of spinel Co3O4 with an average size of 8 nm on reduced GO (RGO) during calcination, which could not be obtained with bulk-layered cobalt hydroxide because of its rapid layer collapse. The ultrafine Co3O4/RGO hybrid exhibited not only comparable performance in the oxygen reduction reaction but also higher durability compared with the commercial 20 wt % Pt/C catalyst.
Conflict of interest
The authors declare no conflict of interest.
