Core-shell structured Ag-CoO nanoparticles with superior peroxidase-like activity for colorimetric sensing hydrogen peroxide and o-phenylenediamine

Exploring of an efficient and cheap-cost peroxidase mimic is crucial for constructing a colorimetric sensing platform. Herein, a series of Ag-decorated CoO nanoparticles (Ag-CoO NPs) were synthesized by a facile one-pot solvothermal strategy and followed by heat treatment. The compositions and morphologies of the as-prepared catalysts were characterized by XRD, N-2-adsorption/desorption, SEM, TEM, XPS, UV-vis diffuse reflectance and transient photocurrent techniques. The core-shell structured 0.10Ag-CoO NPs (molar ratio of AgNO3/Co(NO3)(2) = 0.10) with high dispersion possess large specific surface area (156.8 cm(2) g(-1)) and rich mesoporous structure, thus providing more catalytic active sites. Suitable Ag decoration not only increases the surface active oxygen species and strengthens the visible light respond but also improves the separation of photo-generated electron-hole pairs of 0.10Ag-CoO NPs. As a result, 0.10Ag-CoO NPs exhibit superior peroxidase-like activity for 3,3',5,5'-tetramethylbenzidine (TMB) oxidation in the presence of H2O2 compared to pure CoO NPs and the other nanoparticles. Then a sensitive and selective colorimetric sensing platform was constructed for detecting hydrogen peroxide and o-phenylenediamine. Finally, the possible catalytic mechanism was also proposed here.