Lawrence Berkeley National Laboratory

WO3 thin films are promising photocatalytic materials for PEC water splitting but usually exhibit poor light absorbance in the visible range. In this report, photoactive PVA containing WO3 thin films were prepared by spin-coating method and modified with intense pulsed ion beam (IPIB) irradiation to solve the poor light absorbance problem and improve photocatalytic performance. After irradiation and subsequent annealing, initial PVA containing WO3 thin film turned into porous structures with increased thickness showing increased absorbance and 70 % enhanced photocurrent density at 1.23 V vs. RHE scale compared with only annealed films. It was also investigated that irradiation decreases charge transport properties of spin-coated WO3 thin films. However, such sluggish charge transport kinetics did not hinder photo activity of material due to strong light trapping structure and increased surface-active area of photo electrode after IPIB modification.