Structure and electrochemical property of amorphous molybdenum selenide H2-evolving catalysts prepared by a solvothermal synthesis

Abstract Amorphous molybdenum selenide nanoparticles were synthesized by the solvothermal treatment of Mo(CO) 6 and Se in dimethylformamide. By varying the Mo(CO) 6 over Se molar ratio, we obtained a family of MoSe nanoparticles having comparable morphology but different chemical composition. Using a combination of experimental analyses ( e.g. XRD, ICP-MS, Raman, XPS) and DFT theoretical calculation, we found that the structure of MoSe was close to that of the amorphous molybdenum sulfide analogous but not that of MoSe 2 layers. The MoSe was found to consist of [Mo 3 Se 13 ] 2- cluster within its structure together with some structural defects. Thanks to its less ordered structure, the MoSe can be activated by several chemical and electrochemical treatment resulting in a catalytic enhancement. A treatment with fuming HCl resulted in generation of a novel catalyst displaying 1.4 time higher catalytic current. Remarkably, a treatment with reflux NaOH solution resulted in generation of a component being soluble in water and displaying catalytic H 2 -evolving activity at a moderate onset overpotential of ca. 200 mV, being one of the most attractives homogeneous catalysts in water.