Enhanced visible-light-assisted photocatalytic hydrogen generation by MoS2/g-C3N4 nanocomposites

Abstract

A facile, one-pot, solvothermal synthesis of MoS2 microflowers (S1) and the heterostructures MoS2/g-C3N4 with varying ratios of 1:1 (S2), 1:2 (S3) and 1:3 (S4) exhibiting enhanced visible-light-assisted H2 generation by water splitting has been reported. The compounds were thoroughly characterized by PXRD, FESEM, HRTEM, EDS, UV–vis and XPS techniques. FESEM and HRTEM analyses showed the presence of microflowers composed of nano-sized petals in case of pure MoS2 (S1), while the MoS2 microflowers covered with g-C3N4 nanosheets in case of MoS2/g-C3N4 heterostructure, S4. XPS analysis of S2 showed the presence of 2H phase of MoS2 with g-C3N4. The Eosin-Y/dye-sensitized visible-light-assisted photocatalytic investigation of the samples in the absence of any noble metal co-catalyst revealed very good water splitting activity of MoS2/g-C3N4 heterostructure, S2 with hydrogen generation rate of 1787 μmol h−1g−1 which is about 6 and 40 times higher than pure MoS2 and g-C3N4 respectively. The relatively higher catalytic activity of the heterostructure, S2 has been ascribed to the efficient spatial separation of photo-induced charge carriers owing to the synergistic interaction between MoS2 and g-C3N4. A possible mechanism for the Eosin-Y-sensitized photocatalytic H2 generation activity of MoS2/g-C3N4 heterostructures has also been presented. The enhanced activity of S2 was further supported by fluorescence measurements. Thus, the present study highlights the importance of non-noble metal based MoS2/g-C3N4 heterojunction photocatalysts for efficient visible-light-driven H2 production from water splitting.