One-pot synthesis of pure phase molybdenum carbide (Mo2C and MoC) nanoparticles for hydrogen evolution reaction

Abstract

Herein, we report the one-step synthesis of pure phase molybdenum carbide (Mo2C and MoC) nanoparticles via the in-situ carburization reduction route without using any reducing agent. The X-ray diffraction (XRD) results confirm the formation of pure phase Mo2C and MoC at 800 °C for 8 h and 15 h respectively. The as-synthesized powders have been investigated for hydrogen production and energy storage applications. The pure phase Mo2C shows high performance towards the hydrogen evolution reaction (HER) with a Tafel slope of 129.7 mV dec−1 however, MoC exhibits a low activity towards HER with a Tafel slope of 266 mV dec−1. Both the phases show high stability up to 5000 cyclic voltammetry (CV) cycles in the potential range of 0–0.4 V. In the case of MoC, the specific capacitance increases during the initial 2000 CV cycles which may be attributed to the electrode activation during the CV test. The Mo2C powder shows a double layer capacitance (Cdl) value of 2.47 mF cm−2 and a specific capacitance of 2.24 mF g−1. The MoC phase shows a higher Cdl value of 8.99 mF cm−2 and a specific capacitance of 8.17 mF g−1.