The Pt coated WSe 2 film shows an almost identical SPV curve (Fig. ), compared with the pristine WSe 2 film which proves that the charge carrier separation is not improved by the Pt/WSe 2 Schottky contact (in contrast to the ATM/WSe 2 contact). From the XPS analysis of these different samples, it is found that the deposition of Pt on WSe 2 leads to a Fermi level shift (FLS) of 0.26 eV, i.e. to the change of the FL position from 1.07 to 0.81 eV with respect to the VBM (Fig. ). The Fermi level shift for the Pt/WSe 2 is in agreement with the results of Smyth et al. for the Au/WSe 2 contact. The ATM/WSe 2 sample exhibits a larger FLS of 0.7 eV. This means, Pt on WSe 2 forms a Schottky junction with the weaker FLS, whereas the ATM catalyst forms a stronger heterojunction accompanied by a better charger carrier separation. This explains the higher photoactivity of the ATM/WSe 2 contact compared to that of Pt/WSe 2 .