Solvation effect promoted formation of p-n junction between WO3 and FeOOH: A high performance photoanode for water oxidation

The accumulation of H2O2 on the surface of WO3 in the process of photoelectrochemical (PEC) water splitting leads to the decrease of photoactivity of WO3. To solve this problem, a thin layer of FeOOH acting as water splitting catalyst was coated on the active sites of WO3 surface. The WO3/FeOOH anode, with a deposition time of 20 min, showed a maximum photocurrent of 1.3 mA/cm(2) at 1.23 V vs reversible hydrogen electrode (RHE) under simulated solar illumination (AM 1.5G,100 mW/cm(2)). Furthermore, long time photostability of WO3 was achieved by depositing the FeOOH layer ascribed to its water oxidation ability to generate O-2 rather than H2O2. Interestingly, we found that a p-n junction between WO3 and FeOOH formed due to the different solvation effects on WO3 and FeOOH. The existence of p-n junction favored the transfer of holes from the WO3 to the FeOOH. (C) 2015 Elsevier Inc. All rights reserved.