New insights into the formation of amorphous molybdenum sulfide from a tetrathiomolybdate precursor

Anh D. Nguyen^{1, 2*}, Phuong T. Pham², An T. Dam², Phong D. Tran^2*

¹Graduate University of Science and Technology, Vietnam Academy of Science and Technology

²University of Science and Technology of Hanoi, Vietnam Academy of Science and Technology

Received 30 August 2019; accepted 7 November 2019

 

Abstract:

Amorphous molybdenum sulfide (MoS_x) is an attractive Pt-free catalyst for the hydrogen evolution reaction (HER) in both neutral and acidic pH electrolytes. Among the available approaches for the preparation of MoS_x, the electrochemical oxidation and reduction of a tetrathiomolybdate salt ([MoS₄]^2-) represents the most convenient. Herein we describe new insights onto the electrochemical oxidation of [MoS₄]^2- to grow MoS_x thin films by employing an advanced technique called electrochemical quartz crystal microbalance (EQCM). These new findings enrich the current understanding of the structure, growth mechanism, redox property and catalytic operation of the MoS_x material.

One sentence summary: a new mechanism for growth of amorphous molybdenum sulfide thin films via the electrochemical polymerization of [MoS₄]^2- is discussed.  

Keywords: EQCM, MoS_x formation, [MoS₄]^2-, [Mo₃S₁₁] building block.

Classification number: 2.1