Visible light responsive Fe3O4–WSe2/NG (nitrogen doped graphene oxide) heterojunction nanocomposites were synthesized by a hydrothermal synthesis route, in which Fe3O4 and WSe2 particles were coated on the surface of NG.
The optical absorption edge (E perpendicular to c) was measured on basal-plane samples of single-crystal W1-xMoxSe2(O<or=x<or=1) at temperatures of 15, 78 and 295K. The data were fitted to several expressions for the shape of the edge, with the best fit being to that expected for indirect allowed transitions. The phonon involved is in an optical branch, and its energy varies smoothly with x. The band-gap energy at any temperature varies smoothly with x, indicating that the band edges are the same for MoSe2, WSe2 and the compounds of intermediate compositions.