Photocatalytic water splitting by means of undoped and doped La2CuO4 photocathodes

Thin film electrodes of doped and undoped La2CuO4 powders have been prepared by doctor blading. The La2CuO4 electrode acts as a photocathode for the photoelectrochemical splitting of water and shows a photocurrent of 0.5 mA/cm2. An increase of the photocurrent is observed by doping these electrodes with alkaline earth ions. A maximum efficiency of 0.73% at 45 W/m2 was obtained with a 4% doping of calcium. At higher illumination intensities, the efficiency drops to about 0.2%, due to a rate-limiting step in the charge transfer processes that are involved upon light absorption and the release of hydrogen at the electrode surface. Pt or NiOx have been applied onto the surface by sputtering or by chemical deposition in order to stabilize the photocurrent.