Improving the photocatalytic performance of silver phosphate by thermal annealing: Influence of acetate species

Abstract

Two Ag3PO4 photocatalysts were prepared using different silver precursors (CH3COOAg and AgNO3) and then thermally annealed in air at various temperatures. The surface chemistry of the pristine Ag3PO4 photocatalysts was quite different: the Ag3PO4 sample (AP-C) prepared from CH3COOAg possessed excessive acetate species on its surface while that (AP-N) derived from AgNO3 showed a clean surface. The residual acetate species played crucial role in the thermally excited decomposition of Ag3PO4 into metallic Ag and the simultaneous formation of Ag vacancies. The photocatalytic activity of the pristine AP-C sample was greatly improved after thermal treatment due to the synergistic effect of Ag vacancies and metallic Ag, which contributed to the efficient separation of photogenerated charge carriers. On the contrary, for the AP-N sample, the photocatalytic activity was largely weakened upon thermal annealing because the negative changes in textural structures. Of importance, after impregnation of AP-N in acetic acid solution and annealing, the photocatalytic activity was largely improved.