Sustainable nanoporous gold with excellent SERS performances

Abstract

A low-cost Nanoporous Gold (NPG) has been successfully produced by utilizing the simple method of chemical dealloying. Ribbons of a supersaturated solid solution Au33Fe67 were obtained by rapid solidification using melt-spinning technique. Chemical dealloying of the ribbons was achieved in 1 M HNO3 at 70 °C for varying lengths of time. The as-quenched ribbon and as-dealloyed samples have been structurally and compositionally investigated using XRD, FESEM and EDS techniques. The obtained NPG is homogeneous with tunable ligament size and shape, easy-to-handle and free-standing. NPG has been successfully applied as substrate for Surface-Enhanced Raman Scattering (SERS) using 4,4′-bi-pyridine probe molecule. An impressive enhancement in the SERS effect has been observed. The detection limit is recorded to be as low as 10−15 M. The NPG sample shows great potential as an economical and highly sensitive SERS-active substrate for life science applications and ultrasensitive instrumentation. Catalytic properties have been explored demonstrating a high activity of the material. Most notably, a metastable precursor has been favourably obtained from an immiscible Au–Fe system. Usage of critical raw materials has been avoided. A cost-effective starting material has been used in the form of an Fe-rich precursor by pairing abundant and cheap Fe with Au. Then, an elegant and rapid dealloying procedure makes the overall production of NPG an inexpensive and sustainable process.