We report an economic photocatalytic H-2 generation system consisting of earth-abundant elements only by coupling graphitic carbon nitride (g-C3N4) with Ni(dmgH)(2) sub-microwires that serve as effective co-catalysts for H-2 evolution. This composite photocatalyst exhibits efficient hydrogen evolution under visible-light irradiation in the presence of triethanolamine as electron donor. The optimal coupling of 3.5 wt% Ni(dmgH)(2) to g-C3N4 (5 mg composite) allows for a steady H-2 generation rate of 1.18 mu mol/h with excellent stability. This study demonstrates that the combination of polymeric g-C3N4 semiconductor and small proportion of transition-metal-based co-catalyst could serve as a stable, earth-abundant and low-cost system for solar-to-hydrogen conversion. (C) 2014 Elsevier B.V. All rights reserved.