Wafer scale and substrate-agnostic growth of MoS2 nanowalls for efficient electrocatalytic hydrogen generation in acidic and alkaline media

Emerging as a promising alternative to expensive platinum-based catalysts for electrocatalytic hydrogen evolution reaction (HER), molybdenum disulfide (MoS 2 ) stands out for its favourable thermodynamic properties. However, the catalytic activity of MoS 2 is mostly confined to its edges while the basal plane remains inactive, limiting practical applicability. Fabrication of stable MoS 2 structures with enhanced active sites on a given surface area still remains a complex task. Here we introduce a substrate-agnostic, metal-organic chemical vapour deposition (MOCVD) method for large-area 3D dendritic nanostructures of 2D MoS 2 , termed as “MoS 2 nanowalls”. Using scanning and transmission electron microscopy (SEM/TEM), we elucidate the growth mechanism of the MoS 2 nanowalls and their branched dendritic structure. Even subjected to extreme pH environments (0 and 14) during the HER, the grown MoS 2 nanowalls show remarkable stability even after >170 hours of continuous operation and exhibit excellent catalytic activity with 10 mAcm −2 current density achievable by applying low overpotentials (309±2 mV at pH = 0 and 272±2 mV at pH = 14). The presented large-area growth method for inexpensive MoS 2 nanowall based catalyst can pave the way for practical applications of water electrolysis cells operating at low voltages (≤1.5 V).