Direct water splitting into H and O using photocatalysts by harnessing sunlight is very appealing to produce storable chemical fuels. Conjugated polymers, which have tunable molecular structures and optoelectronic properties, are promising alternatives to inorganic semiconductors for water splitting. Unfortunately, conjugated polymers that are able to efficiently split pure water under visible light (400 nm) via a four-electron pathway have not been previously reported. This study demonstrates that 1,3-diyne-linked conjugated microporous polymer nanosheets (CMPNs) prepared by oxidative coupling of terminal alkynes such as 1,3,5-tris-(4-ethynylphenyl)-benzene (TEPB) and 1,3,5-triethynylbenzene (TEB) can act as highly efficient photocatalysts for splitting pure water (pH ≈ 7) into stoichiometric amounts of H and O under visible light. The apparent quantum efficiencies at 420 nm are 10.3% and 7.6% for CMPNs synthesized from TEPB and TEB, respectively; the measured solar-to-hydrogen conversion efficiency using the full solar spectrum can reach 0.6%, surpassing photosynthetic plants in converting solar energy to biomass (globally average ≈0.10%). First-principles calculations reveal that photocatalytic H and O evolution reactions are energetically feasible for CMPNs under visible light irradiation. The findings suggest that organic polymers hold great potential for stable and scalable solar-fuel generation.
Photoelectrochemical
(PEC) reduction of CO2 into chemical
fuels and chemical building blocks is a promising strategy for addressing
the energy and environmental challenges, which relies on the development
of p-type photocathodes. Cu2O is such a p-type semiconductor
for photocathodes but commonly suffers from detrimental photocorrosion
and chemical changes. In this communication, we develop a facile procedure
for coating a metal–organic framework (MOF) on the surface
of a Cu2O photocathode, which can both prevent photocorrosion
and offer active sites for CO2 reduction. As evidenced
by ultrafast spectroscopy, the formed interface can effectively promote
charge separation and transfer. As a result, both the activity and
durability of Cu2O are dramatically enhanced for PEC CO2 reduction. This work provides fresh insights into the design
of advanced hybrid photoelectrodes and highlights the important role
of interfacial charge dynamics in PEC CO2 conversion.
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