ABSTRACT
Highly efficient proton exchange membrane electrolyzer in acidic media is of great importance for the hydrogen production from the electrochemical water splitting. Unfortunately, the electrochemical water splitting is limited by the slow oxygen evolution reaction kinetics at anode. So far, the synthesis of active and stable electrocatalysts in acid media is still a challenging work. In the work, carbon nanobowls supported ultrafine iridium nanocrystals are synthesized by a simple complexation-reduction method with assistance of 1-hydroxyethane-1, 1-diphosphonic acid, which effectively serves as as complexant, capping agent and surfactant during the synthesis. The good dispersion and ultrafine size of Ir nanocrystals, the modified interfacial property from phosphonate with excellent hydrophilicity, as well as carbon nanobowls as advanced carbon supports contribute to their excellent electrocatalytic activity for the oxygen evolution reaction in acid media. The as-prepared carbon nanobowls supported ultrafine iridium nanocrystals present an ultra-low overpotential of 290â¯mV to achieve the mass activity of 1000â¯Aâ¯g-1 and a small Tafel slope of 49.1â¯mVâ¯dec-1, which significantly outperform commercial Ir/C electrocatalyst. The remarkable activity and durability make carbon nanobowls supported ultrafine iridium nanocrystals as a potential candidate for the oxygen evolution reaction electrocatalyst in proton exchange membrane water electrolyzer.
ABSTRACT
Inspired by graphene, ultrathin two-dimensional nanomaterials with atomic thickness have attracted more and more attention because of their unique physicochemical properties and electronic structure. In this work, the atomically thick ultrathin Rh2O3 nanosheet nanoassemblies (Rh2O3-NSNSs) were obtained by oxidizing the atomically thick ultrathin Rh nanosheet nanoassemblies with HClO. For the first time, Rh-based nanostructures were used as the oxygen evolution reaction (OER) electrocatalyst in an alkaline medium. Surprisingly, the as-prepared Rh2O3-NSNSs displayed extremely improved catalytic activity and durability for the OER compared with those of the commercial Ir/C catalyst and most recently reported Ir-based electrocatalysts. The result indicated Rh-based nanostructures that have great promise to become a potential candidate for efficient OER electrocatalyst because of the similarity of Rh and Ir prices. These experimental results demonstrated the reasonable morphological control of Rh2O3 nanostructures could significantly improve their catalytic activity and durability during heterogeneous catalysis.
