Synergy between AgInS2 quantum dots and ZnO nanopyramids for photocatalytic hydrogen evolution and phenol degradation

Despite the unique properties of single semiconductor nanomaterials and quantum dots, poor photocatalytic activity has characterized them and the fabrication of nanocomposites has become necessary to enhance their photocatalytic performance. Thus, AgInS2 quantum dots (AIS QDs, 4.0 +/- 1.6 nm), have been successfully prepared and loaded onto ZnO nanopyramids (ZnO NPy). The effect of the nominal amount of AIS QDs decorating ZnO NPy on the morphology, optical properties, structure and surface chemistry of the nanocomposites was systematically studied. Photocatalytic tests revealed that the 1%AIS@ZnO NPy sample reported the highest photoactivity for phenol degradation in aqueous phase (92 % after one hour of irradiation, lambda > 350 nm) that was 4 and 68 times the reported for bare ZnO NPy and AIS QDs, respectively. Accordingly, the maximum photocatalytic hydrogen evolution, under UV-vis light, for the same sample corresponded to 17 and 21 times the estimated for pristine ZnO NPy and AIS QDs, respectively. Hence, the AIS QDs - ZnO system has been applied in the photocatalytic field for the first time in this work and a synergetic effect was confirmed owing to a strong heterojunction formation between both semiconductors that allows an enhanced charge carrier separation, improving the photocatalytic activity.