Carbon dots modified molybdenum disulfide as a high-efficiency hydrogen evolution electrocatalyst

Molybdenum disulfide (MoS2) is considered a low-cost material that may replace platinum-based electrocatalysts towards hydrogen evolution reaction (HER). However, the catalytic activity of MoS2 is limited by the low conductivity and lack of active sites. Here, a biomass carbon dots-molybdenum disulfide (BCDs-MoS2) composite was synthesized as a HER catalyst by a simple hydrothermal method. The BCDs-MoS2 catalyst displayed excellent electrocatalytic performance for HER with lower onset overpotential (115 mV), smaller Tafel slope (56.57 mV dec−1) as well as high cycling stability, which superior to those of homemade MoS2, commercial MoS2, and most of the reported MoS2-based catalysts. According to the characterization results of morphology, surface properties, and valence states of elements, the outstanding catalytic activity of BCDs-MoS2 is ascribed to its loose structure with a large specific surface area along with abundant edges and defects, and the increase in the amount of S22− and S2− which possess higher activity due to the addition of the BCDs. This study can afford a new strategy to design high performance HER catalysts.