Electrochemical Behavior of Two-Dimensional Atomic Layers
Doctor of Philosophy
In this thesis several aspects of the electrochemical behaviors of two-dimensional layered materials are discussed. First, large-area continuous few-layer molybdenum disulfide film is prepared by simple solid-gas elemental reaction and transferred onto fluorine doped tin oxide glass substrate as the counter electrode for dye-sensitized solar cells. The catalytic activity of the MoS2 atomic layers are dramatically improved by craving the MoS2 film and creating artificial edges on it. Electrochemical analysis shows that the edges contribute to the improve catalytic activity of MoS2. Second, large-area continuous hexagonal boron nitride film is grown by chemical vapor deposition method. The film is transferred onto copper substrate and tested as the corrosion-inhibiting coating in sodium sulphate aqueous solution. The sample with 30nm h-BN coating shows significantly suppressed copper dissolution peak and only one fourth of the corrosion rate of the uncoated sample. Electrochemical impedance spectroscopy analysis reveals that the charge transfer resistance is much higher when h-BN film is present. Third, we invent a local probe electrochemical measurement method and successfully applied it to the electrolysis catalytic activity measurement of various kinds of transition metal dichalcogenides. The catalytic activity and turnover frequencies of the 2H-MoS2 basal plane versus edge as well as the 1T’-MoS2 basal plane are identified by this measurement. At the same time, the basal plane activity and turnover frequencies of transition metal dichalcogenides from different element groups has been obtained. We have shown that the general trend of the transition metal dichalcogenides in the form of volcano plot follows the trend of metals. VB-VIA dichalcogenides have been identified as the preferential selection for hydrogen evolution reaction catalysts. Last, we discussed the measurement of layered materials in photoelectrolysis using the local probe electrochemical method. Gallium selenide as a good photoconductor, is examined as the photoelectrolysis catalyst and shows promising photoelectrochemical hydrogen evolution performance. The turnover frequency and photon-to-electron conversion efficiency are obtained from our measurements.
2D Materials; Electrochemical Properties; Hydrogen Evolution; Dye Sensitized Solar Cells; Anti-corrosion