▎ 摘　　要

A desirable counter electrode material for dye-sensitized solar cells (DSSCs) needs to have superior electrocatalytic activity, low charge-transfer resistance, and long-term stability. Herein, the development of a composite of nitrogen-doped carbon nano-onions with modified reduced graphene (N-CNOs/mGr) to achieve these merits is reported. The mGr network has high electrical conductivity to improve charge transfer; the N-CNOs with pyridinic and graphitic N provide more electrocatalytic active sites for the reduction ofI(3)(-)toI(-), and the carbon composite demonstrates excellent electrochemical stability. The constructed DSSC with the N-CNOs/mGr electrode presents better long-term stability and a higher power conversion efficiency of 10.28% than those devices with conventional Pt (6.54%) and mGr (5.11%) electrodes. Therefore, the all carbon-based composite will open up new opportunities for a variety of electrochemical device applications.