Trace detection of cyanide based on SERS effect of Ag nanoplate-built hollow microsphere arrays

► The standing Ag nanoplate-built hollow sphere array is a good SERS substrate for KCN detection. ► The detection limit of KCN can be down to 0.1 ppb, being much better than the previous results. ► There exits a linear double-logarithm relation between Raman signal and KCN concentration. ► The suitable immersion and laser power for Raman excitation is crucial to trace detection of KCN.