*3.1. Materials*

Commercial tungsten trioxide powder used as precursor for IF-WS2 nanomaterials was monoclinic WO3 powder (light yellow, with size < 100 nm, purity 99%, Sigma-Aldrich, UK). Ammonium paratungstate (APT, (NH4)10H2(W2O7)6·*x*H2O, 99.99%) particles used to produce WO*<sup>x</sup>* nanoparticles were bought from Sigma-Aldrich, UK. Sulphur (S, sublimed, 100 mesh, 99.5%) was purchased from Cole-Parmer, UK. For comparison with the produced IF-WS2 nanoparticles, 2H-WS2 platelets (powder, 2 m, 99%) were also bought from Sigma-Aldrich, UK.
