▎ 摘　　要

Rational design and construction of non-noble electrocatalysts with high efficiency and good stability is one of the hottest fields for the oxygen reduction reaction (ORR). Herein, for the first time, we describe a novel nanocomposite composed of isolated single-atomic Co sites anchored on 3D hollow graphene nanosphere (Co ISAs/GHS) substrates through a reliable SiO2-assisted strategy. As expected, the as-formed Co ISAs/GHSs exhibit a prominent ORR electroactivity in 0.1 M KOH solution, delivering a more positive half-wave potential of 0.82 V, higher selectivity (four-electron-transfer), and superior methanol tolerance along with long-term stability, originating from the unique components and well-designed structural advantages. Remarkably, the presented work provides a myriad of opportunities to develop highly dispersed single-atomic-site catalysts with highly efficient activity for diverse electrocatalysis applications.