Noble-metal-free g-C3N4/Ni(dmgH)2 composite for efficient photocatalytic hydrogen evolution under visible light irradiation

The noble-metal-free g-C3N4/Ni(dmgH)2 composites show efficient and stable photocatalytic hydrogen evolution under visible light in triethanolamine aqueous solution. •Ni(dmgH)2 sub-microwires as new noble-metal-free co-catalysts for H2 evolution reaction.•Ni(dmgH)2/g-C3N4 composites show highly efficient H2 generation in visible light.•The 1-D feature of Ni(dmgH)2 promotes charge transfer and electron–hole separation on g-C3N4. We report an economic photocatalytic H2 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 H2 evolution. This composite photocatalyst exhibits efficient hydrogen evolution under visible-light irradiation in the presence of triethanolamine as electron donor. The optimal coupling of 3.5wt% Ni(dmgH)2 to g-C3N4 (5mg composite) allows for a steady H2 generation rate of 1.18μmol/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.