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.