Atomic H-Induced Mo2C Hybrid as an Active and Stable Bifunctional Electrocatalyst.

Mo2C nanocrystals (NCs) anchored on vertically aligned graphene nanoribbons (VA-GNR) as hybrid nanoelectrocatalysts (Mo2C-GNR) are synthesized through the direct carbonization of metallic Mo with atomic H treatment. The growth mechanism of Mo2C NCs with atomic H treatment is discussed. The Mo2C-GNR hybrid exhibits highly active and durable electrocatalytic performance for the hydrogen-evolution reaction (HER) and oxygen-reduction reaction (ORR). For HER, in an acidic solution the Mo2C-GNR has an onset potential of 39 mV and a Tafel slope of 65 mV dec-1, and in a basic solution Mo2C-GNR has an onset potential of 53 mV, and Tafel slope of 54 mV dec-1. It is stable in both acidic and basic media. Mo2C-GNR is a high-activity ORR catalyst with a high peak current density of 2.01 mA cm-2, an onset potential of 0.93 V that is more positive vs reversible hydrogen electrode (RHE), a high electron transfer number n (∼3.90), and long-term stability.