Hierarchical spheres constructed by defect-rich MoS2/carbon nanosheets for efficient electrocatalytic hydrogen evolution

Highly active and stable MoS2/carbon hierarchical spheres with abundant active edge sites were fabricated by a simple micro-emulsion procedure where PVP was used as the carbon source, and carbon disulfide as the sulfur source and oil phase in micro-emulsion to control the morphology of MoS2. Hierarchical spheres of MoS2/carbon with a diameter of ca. 500 nm were obtained and characterized by scanning and transmission electron microscopic measurements. With a high electrochemically accessible surface area and defect-rich MoS2 nanosheets, the MoS2/carbon hierarchical spheres exhibited an excellent electrocatalytic activity for hydrogen evolution reaction with a low onset potential of -103 mV (vs. RHE), small Tafel of 56.1 mV dec(-1), as well as extraordinary catalytic stability. The results were accounted for by the "inverted molybdenum reaction" that served as a novel way of regulating Mo catalytic sites of MoS2 electrocatalysts. (C) 2016 Elsevier Ltd. All rights reserved.