A thermally reduced graphene oxide (TRGO) grown with carbon nanotubes composite (G-CNT) was utilized as three-dimensional highly conductive carbon scaffolds, where a large amount of small and homogeneous Pt nanoparticles (from 3.37 +/- 1.22 to 4.24 +/- 1.83 nm) was directly synthesized on G-CNT to acquire a new type of catalyst (Pt/G-CNT). Meanwhile, Pt nanoparticles loaded on TRGO (Pt/TRGO) and on TRGO blended with carbon nanotubes (Pt/G-b-CNT) were prepared for comparison. The G-CNT showed a very high electrical conductivity (144.4 S cm(-1)) compared to the G-b-CNT (67.5 S cm(-1)) and TRGO (9.1 S cm(-1)). In contrast to Pt/G-b-CNT (36.8 m(2) g(-1)) and Pt/TRGO (28.1 m(2) g(-1)), Pt/G-CNT showed a very high electrochemically active surface area (77.4 m(2) g(-1)). As these catalysts were utilized as the anode for the fuel cell, the maximum power density value for Pt/G-CNT (32.0 mW cm(-2)) was about 65% and 74% higher than that of Pt/G-b-CNT (19.4 mW cm(-2)) and Pt/TRGO (18.4 mW cm(-2)), respectively, and 26% higher than that of E-TEK (25.4 mW cm(-2)). (C) 2013 Elsevier Ltd. All rights reserved.