Solar-powered photocatalytic conversion of CO2 to hydrocarbon
fuels represents an emerging approach to solving the greenhouse effect.
However, low charge separation efficiency, deficiency of surface catalytic
active sites, and sluggish charge-transfer kinetics, together with
the complicated reaction pathway, concurrently hinder the CO2 reduction. Herein, we show the rational construction of transition
metal chalcogenides (TMCs) heterostructure CO2 reduction
photosystems, wherein the TMC substrate is tightly integrated with
amorphous oxygen-containing cobalt sulfide (CoSOH) by a solid non-conjugated
polymer, i.e., poly(vinyl alcohol) (PVA), to customize the unidirectional
charge-transfer pathway. In this well-defined multilayered nanoarchitecture,
the PVA interim layer intercalated between TMCs and CoSOH acts as
a hole-relaying mediator and meanwhile boosts CO2 adsorption
capacity, while CoSOH functions as a terminal hole-collecting reservoir,
stimulating the charge transport kinetics and boosting the charge
separation over TMCs. This peculiar interface configuration and charge
transport characteristics endow TMC/PVA/CoSOH heterostructures with
significantly enhanced visible-light-driven photoactivity and CO2 conversion. Based on the intermediates probed during the
photocatalytic CO2 reduction reaction, the photocatalytic
mechanism was determined. Our work would inspire sparkling ideas to
mediate the charge transfer over semiconductor for solar carbon neutral
conversion.