Harnessing self-supported Au nanoparticles on layered double hydroxides comprising Zn and Al for enhanced phenol decomposition under solar light

Gold nanoparticles (AuNPs) self-coupled on semiconductors have attracted extensive attentions in the field of catalysis, however, the progress in understanding and optimizing their photocatalytic performance in response to solar light irradiation is limited. In this paper, a series of AuNPs with Zn2Al-layered double hydroxide (LDH) as support was fabricated via self-assembly routes at room temperature and the tuned oxidation state of AuNPs (as Au-0, Au3+ as well as mixed Au-0/Au3+) was revealed to have a crucial effect on establishing their photocatalytic efficiency for the degradation of phenol from aqueous solution under solar irradiation. X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) analyses permitted to characterize the specific interactions of Zn2Al-LDH with AuNPs and to verify that the state of Au-0/Au(3+)NPs appears due to the electron transfer from Zn2Al-LDH to AuNPs when Zn2Al-LDH reconstruction in the aqueous solution of Au(O2CCH3)(3) was achieved under solar irradiation. On the basis of these AuNPsZn(2)Al-LDH systems, the possible roles of Au-0, Au3+ or Au-0/Au3+ in establishing synergetic effects with Zn2Al-LDHs supports for enhancing the photocatalytic response induced by the irradiation with solar light, for manipulating the mechanism, and the catalyst stability in phenol degradation process, are critically discussed. (C) 2016 Elsevier B.V. All rights reserved.