Electrochemical Applications of Two-Dimensional Nanosheets: The Effect of Nanosheet Length and Thickness

Although many electrochemical properties of 2D materials depend sensitively on the nanosheet dimensions, there are no systematic, quantitative studies which analyze the effect of nanosheet size and thickness on electrochemical parameters. Here we use size-selected WS2 nanosheets as a model system to determine the effect of nanosheet dimensions in two representative areas: hydrogen evolution electrocatalytic electrodes and electrochemical double layer capacitor electrodes. We chose these applications, as they depend on the interaction of ions with the nanosheet edge and basal plane, respectively, and so would be expected to be nanosheet-size-dependent. The data show the catalytic current density to scale inversely with mean nanosheet length while the volumetric double layer capacitance scales inversely with mean nanosheet thickness. Both of these results are consistent with simple models allowing use to extract intrinsic quantities, namely the turnover frequency and the double layer thickness, respectively.