Facet-Inspired Core–Shell Gold Nanoislands on Metal Oxide Octadecahedral Heterostructures: High Sensing Performance toward Sulfide in Biotic Fluids

The development of structurally modified metal oxide heteroarchitectures with higher energy facets exposed has been of extensive research interests because of their unique construction and synergy effect of multifunctioning characteristics. In this study, we reported for the first time the development of a distinct type of gold nanoislands (AuNIs) on metal oxides (i.e., Cu2O–CuO) octadecahedral (ODH) heterostructures through the galvanic exchange reaction, where Cu2O not only acts as a stabilizer but also functions as a reductant. The electrocatalytic performance of the resultant core–shell Cu2O–CuO@AuNI ODH-based electrochemical sensing platform has been evaluated in ultrasensitive detection of sulfide as early disease diagnostics and bacterial marker. Owing to the synergistic collaboration of enhanced surface active sites, exposed {110} crystallographic facets, mixed valances of copper that encourage redox reactions at electrode material/analyte interface, and the polarization effect provide by AuNIs decorated onto the Cu2O surface, Cu2O–CuO@AuNI ODH-modified electrode has demonstrated striking electrochemical sensing performance toward sulfide oxidation in terms of broad linear range, real detection limit down to 1 nM (S/N = 3), and incredible durability and reproducibility. In virtue of marvelous efficiency, the proposed electrochemical sensor based on Cu2O–CuO@AuNI ODH has been employed in in situ sensitive detection of a ubiquitous amount of sulfide engendered by sulfate-reducing bacteria and real-time tracking of sulfide efflux from live cells as early diagnostic strategies.