Atomic H-Induced Mo<sub>2</sub>C Hybrid as an Active and Stable Bifunctional Electrocatalyst.

Fan, Xiujun; Liu, Yuanyue; Peng, Zhiwei; Zhang, Zhenhua; Zhou, Haiqing; Zhang, Xianming; Yakobson, Boris I; Goddard, William A et al. · ACS Nano · 2017

basic_science · Level V

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Abstract

Mo<sub>2</sub>C nanocrystals (NCs) anchored on vertically aligned graphene nanoribbons (VA-GNR) as hybrid nanoelectrocatalysts (Mo<sub>2</sub>C-GNR) are synthesized through the direct carbonization of metallic Mo with atomic H treatment. The growth mechanism of Mo<sub>2</sub>C NCs with atomic H treatment is discussed. The Mo<sub>2</sub>C-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 Mo<sub>2</sub>C-GNR has an onset potential of 39 mV and a Tafel slope of 65 mV dec<sup>-1</sup>, and in a basic solution Mo<sub>2</sub>C-GNR has an onset potential of 53 mV, and Tafel slope of 54 mV dec<sup>-1</sup>. It is stable in both acidic and basic media. Mo<sub>2</sub>C-GNR is a high-activity ORR catalyst with a high peak current density of 2.01 mA cm<sup>-2</sup>, 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.