Herein we report on the use of different metal precursors in the synthesis of MoSe₂ nanomaterials in order to control their morphology. The use of Mo(CO)₆ as the metal precursor resulted in the formation of wrinkled few-layer nanosheets, while the use of H₂MoO₄ as the metal precursor resulted in the formation of nanoflowers. To investigate the effect of the morphologies on their performance as catalysts in the hydrogen evolution reaction, electrochemical characterization was done using linear sweep voltammetry (LSV), cyclic voltammetry (CV), and electrical impedance spectroscopy (EIS). The MoSe₂ nanoflowers were found to have superior electrochemical performance towards the hydrogen evolution reaction with a lower Tafel slope, on-set potential, and overpotential at 10 mA/cm² compared to the wrinkled few-layer nanosheets. This was found to be due to the higher effective electrochemical surface area of the nanoflowers compared to the nanosheets which suggests a higher number of exposed edge sites in the nanoflowers.

A one-step colloidal synthesis of hierarchical nanoflowers of WS₂ is reported. The nanoflowers were used to fabricate a chemical sensor for the detection of ammonia vapors at room temperature. The gas sensing performance of the WS₂ nanoflowers was measured using an in-house custom-made gas chamber. SEM analysis revealed that the nanoflowers were made up of petals and that the nanoflowers self-assembled to form hierarchical structures. Meanwhile, TEM showed the exposed edges of the petals that make up the nanoflower. A band gap of 1.98 eV confirmed a transition from indirect-to-direct band gap as well as a reduction in the number of layers of the WS₂ nanoflowers. The formation of WS₂ was confirmed by XPS and XRD with traces of the oxide phase, WO₃. XPS analysis also confirmed the successful capping of the nanoflowers. The WS₂ nanoflowers exhibited a good response and selectivity for ammonia.