Impact of rare-earth doping on tin disulfide for photocatalytic applications: a first principles insight

The optoelectronic and photocatalytic properties of rare-earth components (RE\(=\) Ce, La, and Sm) incorporated into the \(\hbox {SnS}_2\) structure were investigated using first principles simulations. The TB-mBJ (Tran–Blaha modified Becke–Johnson) approach was used to explore several novel properties. The observed electronic band gap energy of pure \(\hbox {SnS}_2\) is \(E_g = 2.4\) eV, which is in good agreement with the reported experimental value of \(E_g = 2.44\) eV. Results show that doping \(\hbox {SnS}_2\) with RE elements at a concentration of 6.25% significantly reduces the electronic band gap compared to pristine \(\hbox {SnS}_2\). This reduction can be attributed to the smaller ionic radii of \(\hbox {Ce}^{3+}\), \(\hbox {La}^{3+}\), and \(\hbox {Sm}^{3+}\) ions, as well as the appearance of new states hybridized by RE-4f within the band gap, leading to a remarkable enhancement of the absorption spectra in the visible light range. Additionally, the calculated edge positions of the conduction band minimum (CBM) and the valence band maximum (VBM) relative to the normal hydrogen electrode (NHE) for both pristine and RE-doped \(\hbox {SnS}_2\) are optimal for water splitting. Consequently, doping \(\hbox {SnS}_2\) with rare-earth elements appears to be a promising strategy for enhancing its photocatalytic activity in the visible light spectrum.