Manganese dioxide nanostructures: Design, synthesis and conceptualization for developing innovative sensors in reporting environmental risk factors

With the gradual outbreak of environmental safety incidents worldwide, conception and development of high-property sensors for sensitive and accurate detection of environmental risk factors is of great urgency and importance to guarantee environmental security, people’s health and social’s stable development. MnO2 nanomaterials, one subclass of transition metal oxidizes, demonstrate unique catalytic performance, excellent redox activity, high photo-absorption property, large loading/encapsulating efficiency and affluent surface functional groups, and thus provide a significant potential for constructing outstanding analytical platforms. In view of this, substantial efforts have been devoted to developing MnO2-based sensors for sensitive and reliable analysis of environmental risk factors including pesticide, heavy metal ion, anion, antibiotic, biotoxin, and foodborne pathogen. In this review, we summarize the recent progress on design and synthesis of MnO2 with different morphologies, and development and application of MnO2-based sensors for environmental risk factors based on colorimetric, luminescent, electrochemical, photoelectrochemical, electrochemiluminescent and gas generation-initiated distance variation techniques, discuss the present challenges, and propose further advancements in the future to help better realize sensitive, practical and accurate detection of environmental contaminants. We hope this review will not only promote the rapid progress of MnO2-based sensors, but also drive the practical application for environmental risk factors credible sensing in complex matrix, safeguarding the environmental safety.