Facile chemical-vapour-deposition synthesis of vertically aligned co-doped MoS2 nanosheets as an efficient catalyst for triiodide reduction and hydrogen evolution reaction.

• Vertically aligned Co-doped MoS 2 nanosheet array is prepared via CVD sulfurization. • The morphology is controlled by tuning CoCl 2 content in CoCl 2 -MoCl 5 precursor film. • The array exposes active edge sites primarily and facilitates electron transport. • Co-atom doping activates in-plane S atoms presenting at splits of nanosheets. A combination of high surface area, fast-speed charge transportation, excellent intrinsic activity, and low material cost is desired for electrocatalysts' applications, such as hydrogen production, counter electrodes of electrochemical solar cells, etc. In this regard, we originally develop a vertically aligned Co-doped MoS 2 nanosheet array via a facile chemical vapour deposition (CVD) approach that utilizes the reaction between drop-coated CoCl 2 -MoCl 5 precursor film and sulfur vapour released from elemental sulfur powder. Such structure that exposes primarily edge sites of the nanosheets provides reaction with more active centers and guarantees that electrons transport almost along high-electron-mobility basal plane of MoS 2. Simultaneously, the catalytic activity of the in-plane S atoms of MoS 2 , exposing at the splits of MoS 2 nanosheets, can be triggered via Co atom-doping. Such an array that is in-situ grown on graphite foil substrate performs as an efficient electrocatalyst for hydrogen evolution reaction with an overpotential of 185 mV at a current density of 10 mA·cm−2 and an extremely high TOF 0.56 s−1 at 200 mV overpotential, meanwhile, sponsoring as a counter electrode for efficient (8.99%) dye-sensitized solar cells. [ABSTRACT FROM AUTHOR]