Photocarrier relay modulating solar CO2-to-syngas conversion

Solar-driven syngas generation by CO2 reduction provides a sustainable strategy to produce renewable fossil fuels. Nevertheless, this promising approach often suffers from tough CO2 activation, sluggish reaction kinetics and complex selectivity. Herein, we exquisitely constructed spatially directional charge transport channel over two-dimensional transition metal chalcogenide (TMC)-based heterostructure via a facile and universal electrostatic self-assembly method. Tailor-made positively charged non-conjugated insulating polymer of poly(diallyl-dimethyl-ammonium chloride) (PDDA) and negatively charged graphene oxide (GO) precursor as building blocks are controllably anchored on the TMC substrate, by which ultrathin PDDA layer is intercalated at the interface of GO and TMC. We ascertain that, in this customized sandwiched heterostructures, PDDA interim layer functions as an electron-relaying mediator, whilst graphene (GR) obtained from in-situ GO reduction during the photocatalytic reaction serves as a terminal electron-trapping reservoir, synergistically facilitating the spatially vectorial charge separation/migration over TMC, thus endowing the TMC/PDDA/GR heterostructures with conspicuously enhanced visible-light-driven photoactivity toward CO2-to-syngas conversion. Our work would inspire judicious ideas for finely modulating charge transfer over polymer-mediated photosystems and benefit our fundamental understanding of solar CO2 conversion.