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Size Fractionation of Two‐Dimensional Sub‐Nanometer Thin Manganese Dioxide Crystals towards Superior Urea Electrocatalytic Conversion
Author(s) -
Chen Sheng,
Duan Jingjing,
Vasileff Anthony,
Qiao Shi Zhang
Publication year - 2016
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201600387
Subject(s) - manganese , molybdenum disulfide , nanocrystal , nanometre , chemical engineering , urea , electrochemistry , materials science , inorganic chemistry , aqueous solution , suspension (topology) , zeta potential , electrode , nanotechnology , chemistry , nanoparticle , organic chemistry , mathematics , homotopy , pure mathematics , engineering , metallurgy
A universal technique has been proposed to sort two‐dimensional (2D) sub‐nanometer thin crystals (manganese dioxide MnO 2 and molybdenum disulfide MoS 2 ) according to their lateral dimensions. This technique is based on tuning the zeta potential of their aqueous dispersions which induces the selective sedimentation of large‐sized 2D crystals and leaves the small‐sized counterparts in suspension. The electrocatalytic properties of as‐obtained 2D ultrathin crystals are strongly dependent on their lateral size. As a proof‐of‐concept study, the small‐sized MnO 2 nanocrystals were tested as the electrocatalysts for the urea‐oxidation reaction (UOR), which showed outstanding performance in both half reaction and full electrolytic cell. A mechanism study reveals the enhanced performance is associated with the remarkable structural properties of MnO 2 including ultrathin (ca. 0.95 nm), laterally small‐sized (50–200 nm), and highly exposed active centers.