The development of a simple, scalable and reproducible technique for the synthesis of two-dimensional metallic phase MoS2nanosheets is of paramount importance in the field of catalysis and energy storage devices.

H 2 oxidation and O 2 reduction have been studied as a function of temperature at Pt electrodes in the protic ionic liquid diethylmethylammonium trifluoromethanesulfonate. Hydrodynamic voltammetry showed that the H 2 oxidation reaction (HOR) became hindered at positive potentials (>1.0 V). Electrochemical analysis and X-ray photoelectron spectroscopy revealed that this drop in HOR activity was due to the formation of an adsorbed blocking oxide layer, which formed on the Pt surface due to trace H 2 O oxidation at positive potentials. Electrochemical analysis also revealed that the O 2 reduction reaction (ORR) occurred at an appreciable rate only when pre-existing surface oxides were reduced. As the temperature increased, the potential at which the surface oxides were reduced shifted to more positive potentials and the reduction peak narrowed. The net result was significantly higher rates of the ORR at positive potentials at higher temperatures. Finally, even when Pt surfaces were not initially covered with an oxide adlayer, the rate of the ORR increased significantly upon increasing the temperature and some possible reasons for this temperature dependence are discussed.

The effects of electrode-adsorbate interactions on electrocatalysis at Pt in ionic liquids are described. The ionic liquids are diethylmethylammonium trifluoromethanesulfonate, [dema][TfO], dimethylethylammonium trifluoromethanesulfonate, [dmea][TfO], and diethylmethylammonium bis(trifluoromethanesulfonyl)imide, [dema][Tf 2 N]. Electrochemical analysis indicates that a monolayer of hydrogen adsorbs onto Pt during potential cycling in [dema][[TfO] and [dmea][TfO]. In addition, a pre-peak is observed at lower potentials than that of the main oxidation peak during CO oxidation in the [TfO]-based liquids. In contrast, hydrogen does not adsorb onto Pt during potential cycling in [dema][Tf 2 N] and no pre-peak is observed during CO oxidation. By displacing adsorbed ions on Pt surfaces with CO at a range of potentials, and measuring the charge passed during ion displacement, the potentials of zero total charge of Pt in [dema][TfO] and [dmea][TfO] were measured as 271 ± 9 mV and 289 ± 10 mV vs. RHE, respectively. CO displacement experiments also indicate that the [Tf 2 N]ion is bound to the Pt surface at potentials above-0.2 V and the implications of ion adsorption on electrocatalysis of the CO oxidation reaction and O 2 reduction reaction in the protic ionic liquids are discussed.

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