Surface-enhanced Raman scattering of trace Hg2+ on a 4-mercaptobenzoic acid-modified nanoporous Au substrate

A Au-Ga alloy layer is synthesized on a Au sheet substrate at low temperature and a new nanoporous Au material is then prepared based on Ga removal from the Au-Ga alloy by a electrochemical method. X-ray diffraction analysis confirms that the grains of the newly formed Au layer are refined and scanning electron microscopy suggests that the newly formed Au layer has a nanoporous structure with a pore size of∼16 nm. The cyclic voltammetry curve of the prepared nanoporous Au in a 1 M KCl solution presents a square structure of a supercapacitor with a specific capacitance of mF·cm-2, which is 86 times that of the smooth Au electrode. The 4-mercaptobenzoic acid (4-MBA) modified nanoporous Au material is used as a Raman substrate to detect Hg2+ with surface-enhanced Raman scattering. from 1.0×10−10 mol·L-1 to 1.0×10−5 mol·L-1), and the limit of detection is 1.0×10−10 mol·L-1.