Facile one-pot surfactant-free synthesis of 3D vertical graphene anchored ultrafine PtCo nanoparticles for ethanol oxidation

Abstract

Exploring highly active catalysts with high Pt utilization rates is still challenging for direct ethanol fuel cells (DFECs). Herein, we report a facile synthesis of three-dimensional (3D) vertical graphene (VG) supported PtCo alloy nanoparticles (PtCo/VG) as catalysts for ethanol oxidation reactions (EOR). The 3D interconnected open network and exposed edges of VG nanosheets provide an ideal support for hindering the aggregation of PtCo nanoparticles and thus the PtCo nanoparticles achieve an ultrasmall size of 3.7 nm and a high dispersion on VG supports. PtCo/VG displays a superb mass activity (4.33 A mg⁻¹) and specific activity (5.14 mA cm⁻²) toward EOR, which are 5.6 and 3.5 times to those of commercial Pt/C, respectively. The catalytic activity of PtCo/VG also surpasses its counterparts of carbon fibers supported PtCo (PtCo/CNFs) and XC-72 supported PtCo (PtCo/XC-72), and behaves amazingly among many reported Pt-based catalysts. Density functional theory (DFT) calculations demonstrate that the introduction of VG supports lowered the Pt d-band center, weakened the CO adsorption and strengthened the OH adsorption on catalytic sites of PtCo/VG. This work may pave the way for fabricating highly carbon-based efficient bifunctional electrocatalysts with high platinum utilization for fuel cells.