Liquid-phase exfoliated MoS₂ nanosheets doped with p-type transition metals: a comparative analysis of photocatalytic and antimicrobial potential combined with density functional theory

In order to enhance its photocatalytic properties, the host material was doped with p-type transition metals (Ag, Co, Bi, and Zr). The hydrothermal technique was used to produce samples doped with 7.5 wt% transition metals. Raman analysis was undertaken to identify molecular vibrations. The A_1g mode in Raman spectra consistently showed a blueshift in all samples and the E_12g mode was only slightly affected, which is evidence of the p-type doping in the MoS₂ nanosheets. Diverse morphologies were observed with a non-uniform distribution of the dopant. Photocatalytic action of the TM-doped products effectively degraded MB concentrations of up to 94 % (for Ag-MoS₂). Moreover, results from first-principles calculations indicate that substitutional doping of TM atoms is indeed advantageous. DFT confirmed that doping with Ag, Co, Bi, and Zr leads to a decrease in the bandgap to a certain degree, in which the conduction band edge shifts toward lower energy, while the valence band shifts closer to the high energy end. It can be concluded that Ag, Co, and Bi impurities can lead to beneficial p-type doping in MoS₂ monolayered structures. With regards to doping with Zr, the acceptor levels are formed above the edge of the valence band, revealing an introduction of the p-type character.