3099160 MnO2 delta-MnO2 nanosheets on flexible carbon cloth substrate 1 3099158 MnO2 Mn3+ was far more efficient than Mn2+, Mn4+ 1 3099161 MnO2 MnO2 /PDA@Cu, comprising manganese dioxide 1 3099159 MnO2 mTorr of O2 leads to mixed-terminated film surfaces, with B-site 1