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

Graphical abstract: The noble-metal-free g-C₃N₄/Ni(dmgH)₂ composites show efficient and stable photocatalytic hydrogen evolution under visible light in triethanolamine aqueous solution. - Highlights: • 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. - Abstract: 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 3.5 wt% Ni(dmgH)₂ to g-C₃N₄ (5 mg composite) allows for a steady H₂ generation rate of 1.18 μmol/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