Carbon nanotubes-supported Ag/MoO2 or Ag/MnO2 heterostructures for a highly efficient oxygen reduction reaction

Supported by carbon materials and adjusting Ag surface states by metal oxides are two effective methods to promote the oxygen reduction reaction (ORR) performance of Ag-based catalysts. Herein, combining these two strategies, two kind of heterostructural electrocatalysts, carbon nanotubes-supported Ag/MoO2 (CNTs-Ag/MoO2) and carbon nanotubes-supported Ag/MnO2 (CNTs-Ag/MnO2) are constructed by facile two-step methods for the superior ORR catalytic activity in alkaline medium. Both CNTs-Ag/MoO2 and CNTs-Ag/MnO2 exhibit more positive onset potential and higher half-wave potential (~0.93 V and ~ 0.81 V (vs RHE) for CNTs-Ag/MoO2, ~0.99 V and ~ 0.86 V (vs RHE) for CNTs-Ag/MnO2), comparable and even superior to commercial Pt/C(~0.95 V and ~ 0.82 V(vs RHE)), which are benefit from Ag surface states regulation and the oxygen vacancy formation induced by the introduction of MoO2 or MnO2, as well as the enhanced electron transmission and dispersion of Ag/MoO2 or Ag/MnO2 resulted from the activated CNTs supporting. This work provides a useful reference to design efficient Ag-based ORR electrocatalysts with the superior performance.