Photocatalytic generation of hydrogen under visible light on La2CuO4

The semiconducting properties of La2CuO4 prepared by a chemical route are investigated for the first time by the photo-electrochemical technique. The optical gap is found to be 1.27 eV and the transition is directly allowed. p-Type conductivity is demonstrated from the Mott-Schottky plot in alkaline KOH solution (0.1 M), extrapolation of the linear region to the potential axis gives a flat band potential of -0.41 V-SCE, a holes density of 1.75 x 10(19) cm(-3) and a space-charge region of 18 nm. The electrochemical impedance spectroscopy, measured over the frequency range (1 mHz-10(5) Hz), reveals the predominance of the bulk contribution with a constant phase element. The energy diagram shows the feasibility of La2CuO4 for the H-2 evolution under visible light. The best performance occurs at pH 12.5 in the presence of S as holes scavenger. A liberation rate of 20.6 mu mol mn(-1) (g catalyst)(-1) is obtained under full light (29 mW cm(-2)).