Edge-dominated hydrogen evolution reactions in ultra-narrow MoS₂ nanoribbon arrays

Future energy generation and storage requirements emphasize the importance of high-performance electrocatalysis. MoS2 edges exhibit ideal energetics for hydrogen evolution reactions (HERs) if challenges in their kinetics are addressed. Herein, we investigate the emergence of edge-dominated electrochemical reaction kinetics in ultra-narrow MoS2 nanoribbons. A templated subtractive patterning process (TSPP) served as a powerful platform that yields large arrays of MoS2 nanoribbons. Nanoribbons with widths below 30 nm exhibit significantly increased reaction kinetics, as evidenced by a & SIM;200-fold enhanced turn-over frequency, an 18-fold increased exchange current density, and a 38% decreased Tafel slope. These improvements are due to increased charge transfer efficiency from the basal plane toward the edge sites. Photo-electrocatalytic measurements and carrier transport simulations reveal the impact of suppressed band bending in nanoribbons below the depletion width toward achieving edge-dominated HER. Our results demonstrate the potential of confinement in electrocatalysis and provide a universal route toward nanoribbon-enhanced electrochemistry.