Three graphite materials with different structures, including graphite nanofiber (GNF), graphite nanosheet (GNS), and graphite nanoball (GNB), were used as the catalytic films on the counter electrodes (CEs) of dye-sensitized solar cells (DSSCs). Compared to GNF and GNS, GNB not only provides a higher degree of defects in the sp(2) plane structure but also possesses aboundant hydroxyl functional groups as the electro-catalytic active sites for I-3 reduction; thereby, the intrinsic heterogeneous rate constant (k(0)) and effective electro-catalytic surface area (A(e)) of GNB-based CE are both higher than the values of GNF-based and GNS-based CEs. The GNB-based DSSC with showed the power conversion efficiency (eta) of 7.88%, while those GNF-based and GNS-based DSSCs showed eta's of 3.60% and 2.99%, respectively. Moreover, it is also observed that the eta of the GNB-based DSSC (7.88%) is quite close to that of a Pt-based DSSC (eta=8.38%); this implies that the GNB can become a potential candidate to replace the expensive Pt, owing to its low-cost. (C) 2015 Elsevier Ltd. All rights reserved.