Engineered Co3O4 Nanoboxes Boost Luminol Chemiluminescence for Selective Mn2+ Sensing

Abstract

Chemiluminescence (CL) is a powerful analytical tool that has gained more interest in various fields due to its rapid response, simplicity, cost-effectiveness, and higher sensitivity compared to traditional complex methods for detecting trace toxic metals. The traditional luminol/H2O2 CL method suffers from low emission efficiency. As a result, the synthesis of nanozymes as co-reaction accelerators has attracted increasing attention to improve CL sensitivity. Spinel-type oxides have been used in many fields because of their cost-effectiveness, excellent catalytic performance, and eco-friendliness; however, they have seldom been used in CL. Herein, a simple chemical etching method of self-templating ZIF-67 nanocubes MOF precursor by tannic acid, followed by thermal annealing, was employed to synthesize Co3O4 nanoboxes (NBs). The Co3O4 NBs showed peroxidase-like activity and boosted the luminol/H2O2 CL by a factor of 670. The improved catalytic efficiency is attributed to an increased H2O2 adsorption on the confined surfaces of Co3O4 NBs, generating more reactive oxygen species radicals and significantly enhanced luminol/H2O2 CL signal. Moreover, Mn2+ remarkably quenched CL, enabling highly sensitive Mn2+ detection with a wide linear range from 50 nM to 5 µM and a limit of detection as low as 2.5 nM.