Determination of Hg 2+ and Cu 2+ ions by dual-emissive Ag/Au nanocluster/carbon dots nanohybrids: Switching the selectivity by pH adjustment.

•Preparation of a dual-emissive nanohybrid probe consisting of red Ins(Au/Ag)NCs and blue CDs.•Characterization of nanomaterials via FTIR, XPS, TEM, zeta potential, and photoluminescence spectroscopy.•Application of nanohybrid probe to highly selective ratiometric sensing of Hg2+ and Cu2+ ions.•Switching of selectivity of nanohybrid probe toward Hg2+ and Cu2+ ions by simple control of pH.•Detection limits of 5 nM at pH 10.0 for Cu2+ and 7 nM at pH 4.0 for Hg2+ ions.