MoS2 and WS2 nanocone arrays: Impact of surface topography on the hydrogen evolution electrocatalytic activity and mass transport
By Escalera-L
Published in Applied Materials Today
2018
Abstract
We report the fabrication and electrochemical study of edge-abundant transition metal dichalcogenide (TMD) nanocone arrays. Time-dependent etching by sequential use of isotropic O2 and anisotropic SF6/C4F8 plasmas on nanosphere monolayer-modified TMD crystals results in very high coverage nanocone array structures with tunable aspect ratios and interspacings. Electrochemical characterization of these arrays via the hydrogen evolution reaction (HER), using a low proton concentration electrolyte (2mM HClO4, 0.1M NaClO4) to reveal morphology-dependent mass transport features at the proton diffusion-controlled region, show significant changes in electrocatalytic behaviour at both WS2 and MoS2: notably onset potential shifts of 100 and 200mV, and Tafel slope decreases of 50 and 120mVdec?1 respectively. These improvements vary according to the geometry of the arrays and the availability of catalytic edge sites, and thus the observed electrochemical behaviour can be rationalized via kinetic and mass transport effects.