Ultrasensitive and dual functional colorimetric sensors for mercury (II) ions and hydrogen peroxide based on catalytic reduction property of silver nanoparticles

► Dual functional colorimetric sensors for mercury (II) ions and hydrogen peroxide. ► Hg2+ was reduced to elementary Hg by silver nanoparticles in the presence of H2O2. ► This method had ultra-high sensitivity and good selectivity.