Vertically oriented Ni-doped MoS2 nanosheets supported on hollow carbon microtubes for enhanced hydrogen evolution reaction and water splitting.

Developing efficient hydrogen evolution reaction (HER) electrocatalysts is extremely important for large-scale hydrogen production from water splitting. In this work, ultra-small MoS 2 nanosheets with 5% Ni doping grown on both sides of hollow carbon microtubes (5%-Ni-MoS 2 /aCMT) are prepared by a hydrothermal method. The vertically oriented Ni-doped MoS 2 nanosheets provide more active sites for HER, while open porous structure promotes ions transport, and hollow carbon microtube substrate accelerates electrons transport as well as hydrogen release. Density functional theory (DFT) analysis proves that the optimal amount of Ni doping can effectively adjust the electronic structure of MoS 2. As a result, 5%-Ni-MoS 2 /aCMT electrode exhibits enhanced kinetics for HER in both acidic and alkaline conditions. To deliver the current density of 10 mA cm−2, it requires overpotentials of 140 and 88 mV in 1 M KOH and 0.5 M H 2 SO 4. 5%-Ni-MoS 2 /aCMT exhibits better stability than commercial Pt/C at a high current density of 200 mA cm−2. Moreover, 5%-Ni-MoS 2 /aCMT/NF (nickel foam) || RuO 2 /NF electrolyzer exhibits ultra-long stability of 30 h at the current density of 100 mA cm−2 and excellent overall water splitting performance with requiring low cell voltages of 1.52 and 1.71 V to generate current densities of 10 and 50 mA cm−2. [Display omitted] • The Ni doping with an optimized content adjusted the electronic structure of MoS 2 , and improved the intrinsic activity. • The ultra-small vertically oriented and defect-rich Ni-doped MoS 2 nanosheets provide more active sites for HER. • The natural N-doped aCMT substrate promotes electron transport during the HER process. • 5%-Ni-MoS 2 /aCMT behaves an enhanced kinetics process based on EIS and DFT analysis. [ABSTRACT FROM AUTHOR]