Understanding the Synergistic Oxidation in Dichalcogenides through Electrochemiluminescence Blinking at Millisecond Resolution.

ABSTRACT

The oxidation of transition metal dichalcogenides (TMDCs) has been extensively studied and applied in electronics, optics, and energy sources because of its tunable structure and performance. However, due to the lack of appropriate technology, dynamically observe the oxidation process remains an arduous task. Herein, the synergistic oxidation between edge and basal plane in molybdenum disulfide (MoS2 ) is observed through electrogenerated chemiluminescence (ECL) blinking with a millisecond resolution. In addition, the ECL method provides a simple, convenient, and quick way to judge structural changes. The transient elevation of the ECL intensity proved the intermittent doping of oxygen at MoS2 , which generates O-atom active sites. High ECL intensity enhanced from the produced hydroperoxide intermediates eases the monitoring of MoS2 particles. Further study shows that the formation of sulfur vacancies at MoS2 , by the edge activation of hydrogen peroxide and the migration of oxygen to the basal plane, is more conducive to oxygen doping that favors the formation of MoOMo as new active sites to induce bursts. The revealing of sulfur vacancy-governed blinking from MoS2 indicates a complex interaction between oxygen and MoS2 . The same phenomenon is observed on tungsten disulfide (WS2 ), which provides new information about the oxidation feature of 2D dichalcogenides.