(339f) Engineering the Surface Structure of MoS2 Through Morphological Control At the Nano-Scale for Enhanced Electrocatalytic Hydrogen Production

MoS₂ nanoparticles have been shown to exhibit excellent turnover frequencies for the hydrogen evolution reaction (HER) due to the presence of undercoordinated edge sites with high catalytic activity.¹  In order to achieve high electrode current densities, the density of these edge sites must be increased and vertically integrated into a conductive architecture.  However, simply creating high surface area morphologies of nanostructured MoS₂ will often yield sub-optimal results since the formation of highly energetic and catalytically active edge sites is thermodynamically unfavored compared to the formation of extended non-active basal planes.  Charge transport can also be problematic. Herein, we show how engineering nano-architectures of MoS₂ by scalable methods can produce materials with high surface area as well as the appropriate surface structure exposed to the electrolyte in order to deliver high catalytic activity and stability. One example is that of a core-shell architecture of MoO₃-MoS₂ which we engineered for both effective charge transport and stability, enabling highly efficient HER over thousands of simulated diurnal cycles with demonstrated viability for integration into a solar water splitting device.²  Another example includes a mesoporous double-gyroid morphology of MoS₂ with a high radius of curvature ~2-4 nm that inhibits the formation of thermodynamically favored basal planes, enhancing the population of edge sites and yielding extremely high activity for the HER that is within 100 mV of the best precious metal catalysts.³  The approaches highlighted in this work serve as guiding principles for the development of novel electrocatalysts through morphological control at the nanoscale.

(1)           T.F. Jaramillo, K. P. Jørgensen, J. Bonde, J. H. Nielsen, S. Horch, I. Chorkendorff, “Identifying the active site: Atomic-scale imaging and ambient reactivity of MoS₂ nanocatalysts,” Science, Vol. 317, No. 5834, pp. 100-102, 2007.

(2)           Z. Chen, D. Cummins, B.N. Reinecke, E. Clark, M. Sunkara, T.F. Jaramillo, “Core-shell MoO₃-MoS₂ Nanowires for Hydrogen Evolution: A Functional Design for Electrocatalytic Materials,” Nano Letters, Vol. 11, pp. 4168-4175, 2011.

(3)           J. Kibsgaard, Z. Chen, B.N. Reinecke, T.F. Jaramillo, "Engineering the surface structure of MoS₂ to preferentially expose active edge sites for electrocatalysis" (submitted).