Robust Mesoporous Manganese Oxide Catalysts for Water Oxidation

Abstract

Inspired by the natural oxygen evolution\nreaction of Photosystem\nII, the earth-abundant and inexpensive manganese oxides (MnO_<i>x</i>) have been recognized for their great potential\nas highly efficient and robust materials for water oxidation reaction\n(WORs). To date, most of the heterogeneous, synthesized MnO_<i>x</i> catalysts still exhibit lower activities for WORs,\nin comparison to RuO₂ and IrO₂. Herein, we report\na single-step and scalable synthesis method for mesoporous MnO_<i>x</i> materials that is developed through a soft-templated\nmethod. This method allowed precise control of Mn³⁺-rich\nMn₂O₃ structure as well as pore sizes and crystallinity\nof these mesoporous MnO_<i>x</i>. These catalysts\nwere investigated for both photochemical and electrochemical water\noxidation, and they presented a superior activity for water oxidation.\nThe highest turnover frequency of 1.05 × 10^–3 s^–1 was obtained, which is comparable with those\nfor precious metal oxide based catalysts (RuO₂ and IrO₂). Our results illustrate a guideline to the design and synthesis\nof inexpensive and highly active heterogeneous catalysts for water\noxidation.