The reactor was naturally cooled to room temperature and the precipitate was washed three times with ethanol and dried in a vacuum oven for 2h at 70°C. Physical characterization: Scanning electron microscopy (SEM) images and EDS maps of the VS2 microflowers were collected on a Zeiss Auriga SEM operated at an accelerating voltage of 5 kV (working distance ∼ 5 mm). Powder X-ray diffraction was performed on the hydrothermal VS2 with a Bruker D2 Phaser diffractometer equipped with a copper source in the range 2-60° for 2θ and with an angular step size of 0.034°. Raman spectra were acquired using a Renishaw inVia Qontor confocal Raman microscope at a wavelength of 532 nm. X-Ray photoelectron spectroscopy. XPS was performed using a Thermo Scientific K-Alpha+ with a monochromated Al X-ray source (hν = 1486.6 eV). The spectra were collected using pass energies of 200 eV for the survey and 20 eV for the core levels under a 200 μm spot size. HR TEM images and ADF STEM images were acquired on a JEOL JEM-2100F microscope with a field-emission gun operated at 200 kV accelerating voltage.