Spectroscopy

Quantum mechanics

Catalysis

Acceptor

Chemical physics

Photochemistry

Materials science

Nanosheet

Semiconductor

Dissociation (chemistry)

Physical chemistry

Physics

Nanotechnology

Organic chemistry

Exciton

Charge carrier

Condensed matter physics

Chemistry

Covalent bond

Photocatalysis

Optoelectronics

Ultrafast laser spectroscopy

Nature Communications

Organic semiconductors offer a tunable platform for photocatalysis, yet the more difficult exciton dissociation, compared to that in inorganic semiconductors, lowers their photocatalytic activities. In this work, we report that the charge carrier lifetime is dramatically prolonged by incorporating a suitable donor-acceptor (β-ketene-cyano) pair into a covalent organic framework nanosheet. These nanosheets show an apparent quantum efficiency up to 82.6% at 450 nm using platinum as co-catalyst for photocatalytic H 2 evolution. Charge carrier kinetic analysis and femtosecond transient absorption spectroscopy characterizations verify that these modified covalent organic framework nanosheets have intrinsically lower exciton binding energies and longer-lived charge carriers than the corresponding nanosheets without the donor-acceptor unit. This work provides a model for gaining insight into the nature of short-lived active species in polymeric organic photocatalysts.

Covalent organic frameworks with high quantum efficiency in sacrificial photocatalytic hydrogen evolution