Epitaxial Bi4O5Br2 nanosheets on hollow carbon spheres for confined electron pump reactor and enhanced photocatalytic CO2 hydrogenation reduction

In order to enhance the efficiency of artificial photosynthesis, it is imperative to improve the hysteretic migration and separation efficiency of photogenerated charge carriers. Herein, ultrathin Bi 4 O 5 Br 2 (BOB) nanosheets are prepared vertically and uniformly on the surface of hollow N-doped carbon spheres (NC) to produce a hollow confined nanoreactor (BOB@NC). The graphite layer and N in NC act as a tandem electron pump for the rapid transfer of photogenerated electrons from BOB to the NC surface via the Bi-C bridging bond between BOB and NC, and the electrons on the NC surface continue to move to the N-induced defect energy levels. This NC electron pump facilitates the transfer of the photogenerated electrons in a directional, rapid, and efficient manner. Meanwhile, the adsorption of CO 2 molecules and hydrogenation of *CO to *CHO at the N site on NC are kinetically spontaneous, thereby significantly reducing the CO 2 reduction reaction energy barrier of BOB. As a result, the efficiency of CO 2 hydrogenation reduction to CO and CH 4 by BOB@NC is 3.31 and 11.15 times higher than that by the BOB monomer, respectively. The hollow confined electron pump reactor reveals a novel strategy for the design and fabrication of catalysts for high-performance artificial photosynthesis.