The highest reported photocurrent density for a WSe 2 single crystal under simulated AM 1.5 illumination is about 25 mA cm -2 under short circuit conditions (0 V vs. RHE) in an acidic solution. However, for large scale applications, WSe 2 single crystals cannot be used due to their high costs. Recently, for WSe 2 polycrystalline films a photocurrent density of about 4 mA cm -2 at 0 V vs. RHE was demonstrated. In this case, the highest photocurrent density was reached due to the passivation of the edges sites of the WSe 2 crystallites with the Pt/Cu catalyst.