Effects of grain morphology, microstructure and dispersed metal cocatalyst on the photoreduction of water over impurity-doped LaInO3

The single phase lanthanum indates doped with Ga (for La) and N (for O), i.e. La1−xGaxInO3 (0 ≤ x ≤ 0.2) and LaInO1−yNy (y ∼ 0.6), exhibit significant activity for photoreduction of water; the yield of H2 produced depending on dopant, excitation source, and addition of a sacrificial reagent. The two-step H2 evolution observed for this reaction corresponds with the two distinct absorbance regimes displayed by these materials, one in UV-region due to bandgap excitation and the other in visible region arising from the transitions involving sub-bandgap donor or acceptor energy states. The photocatalytic activity of these d10 metal oxides increases on coating with a metal/metal oxide co-catalyst, gold exhibiting superior activity to Pt and NiO, irrespective of excitation source and sample composition. The preparation-controlled particle morphology, doping-induced lattice imperfections, and metal/semiconductor hetero-junctions are envisaged to play a key role in the absorption characteristics and photocatalytic water reduction activity of metal/LaInO3 nanocomposites.