In this paper, Co nanorods with extremely high length to diameter and preferred exposed (101) facet were synthesized by carboxyl-assisted over graphite oxide surface. DFT calculation results indicated that (101) facet Co nanorods exhibited higher surface energy of (101) facets (2.61 J/m(2)) than that of (100) planes nanorods (2.46 J/m(2)). Such Co nanorods showed very low over-potential for proton reduction, about 0.20 V onset overpotential and 400 and 510 mV at current densities of 2 and 5 mA/cm(2), and worked as high active co-catalyst for photocatalytic hydrogen evolution. Co (101) nanorods loaded catalyst generated 891.3 mu mol H-2 in 2 h, while Co nanoparticles only gave 451.6 jimol of hydrogen during same time. The apparent quantum efficiency (AQE) of Co nanorods catalyst achieved 17.4% at 520 nm. This work opened a news strategy for design of with rodlike structure cocatalyst with preferred exposed high surface energy facet for photocatalytic hydrogen evolution reaction though the carboxylation of GO. (C) 2016 Elsevier B.V. All rights reserved.