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

• Published in: International Journal of Hydrogen Energy Vol. 44; no. 26; pp. 13273 - 13283
• Main Authors: Nguyen, Chuc T., Duong, Tuan M., Nguyen, Mai, Nguyen, Quyen T., Nguyen, Anh D., Dieu Thuy, Ung Thi, Truong, Quang Duc, Nguyen, Tung T., Nguyen, Quang Liem, Tran, Phong D.
• Format: Journal Article
• Language: English; Japanese
• Published: Elsevier Ltd 21.05.2019; Elsevier BV
• Subjects: Catalysis; Chalcogenide; Hydrogen; Molybdenum selenide; Water electrolysis; Chalcogenide; Water electrolysis; Molybdenum selenide; Catalysis; Hydrogen
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2019.03.186

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 MoSe2 layers. The MoSe was found to consist of [Mo3Se13]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 H2-evolving activity at a moderate onset overpotential of ca. 200 mV, being one of the most attractives homogeneous catalysts in water. [Display omitted] •Amorphous MoSe is constituted of [Mo3Se13]2- building block and Mo-vacant defects.•Composition and catalytic activity of MoSe depends on the Mo:Se precursor ratio.•Chemical treatment with HCl or electrochemical treatment enhances MoSe activity.•MoSe treatment with NaOH generates the [Mo1.1Se] as excellent homogeneous catalyst.•Origin of pre-peak reduction is studied by chemical and electrochemical analyses.