Fully Conjugated Covalent Organic Polymer with Carbon-Encapsulated Ni2P for Highly Sustained Photocatalytic H2 Production from Seawater.

Organic photocatalysts are widely used to mimic artificial photosynthesis for sustainable solar-driven hydrogen production from water splitting. However, few photocatalytic H2 production is reported using seawater, which is a significantly important parameter for practical application, and most organic photocatalysts employed precious and scarce Pt as a cocatalyst. Herein, we report an organic hybridized photocatalyst (termed COP-TF@CNi2P), carbon-encapsulated nickel phosphide, as a cocatalyst loaded on a fully conjugated organic polymer, which is applied for stable and efficient H2 generation from seawater splitting. Both experiments and theory calculations suggest that the carbon layers covered around nickel phosphide not only can strengthen π-π interactions with the polymers but also can attract the photoinduced electrons from COP-TF to the surface of CNi2P, which contributes to expedite exciton dissociation. As a result, the as-synthesized COP-TF@CNi2P achieves a remarkable photocatalytic H2 production efficiency up to 2500 μmol g-1 h-1 (λ ≥ 400 nm) from seawater and even maintains 92% of initial efficiency after 16 intermittent cycles, which lasts for half a month.