Silver enriched silver phosphate microcubes as an efficient recyclable SERS substrate for the detection of heavy metal ions

A rapid, cost-effective and accurate detection of heavy metal ions is crucial for human health monitoring and environmental protection. Surface-enhanced Raman spectroscopy (SERS) has become a reliable method due to its outstanding performance for the identification of contaminants. In this paper, silver phosphate microcubes (Ag3PO4) were fabricated using two different precipitation methods for ultrasensitive SERS detection of heavy metal ions. The use of an organic linker (BPy) with Ag3PO4 enabled the immobilization of Hg2+ and Pb2+ ions. The formation of Ag3PO4 was confirmed by XRD, UV-DRS, FESEM coupled with EDX and HRTEM. The analytical enhancement factor (AEF) obtained was 1010 with a detection limit of 10-15 M indicating high sensitivity. Based on these results, the possible SERS mechanism has been proposed and discussed. Moreover, an excellent reusability of Ag3PO4 substrate for at least four cycles was achieved upon the light exposure on heavy metal loaded substrate due to its superior catalytic ability for the degradation of heavy metal ions. The as-prepared substrate demonstrated remarkable stability, selectivity and SERS sensitivity towards real samples. The results conclude that Ag3PO4 microcubes offer a great prospect in recyclable SERS applications.