Sunlight‐assisted environmentally-friendly synthesis of graphene-like δ-MnO2 nanosheets for colorimetric sensing

Abstract

Manganese dioxide (MnO2) has received increasing attention for sensing applications due to its versatile properties. Thus, there is a need to develop a facile strategy to synthesize MnO2. Herein, a template-free, green, photoinduced synthesis method for graphene-like δ-MnO2 nanosheets (GLMNS) was developed using potassium permanganate as the precursor. In the proposed synthesis strategy, trace ethanol was employed as the electron acceptor to direct the template-free, one-step growth of dispersed ultrathin multi-layered GLMNS under sunlight irradiation, without requiring another reducing agent or surface stabilizer. As a proof of concept, as-synthesized GLMNS were employed as a homogeneous nanocatalyst and signal-reporting material for two different sensitive colorimetric detection methods for triclosan and total antioxidant capacity. The two colorimetric methods were also evaluated by detecting triclosan in real sewage and silt samples, as well as the total antioxidant capacity of human blood serum. This study indicates that using sunlight irradiation to prepare two-dimensional MnO2 nanosheets is a promising strategy and also offers promising homogeneous MnO2-based colorimetric detection strategies. As a result of this work, we may be able to prepare MnO2 nanosheets in a new way, and it is also possible that GLMNS may be a good candidate for other applications, such as pseudocapacitive and adsorbent.