Artificial Trees for Artificial Photosynthesis: Construction of Dendrite-Structured α-Fe₂O₃/g-C₃N₄ Z-Scheme System for Efficient CO₂ Reduction into Solar Fuels

Abstract

A direct all-solid-state Z-scheme heterojunction photocatalyst of a g-C3N4-coated tree-like α-Fe2O3 was rationally constructed toward CO2 conversion. The so-called artificial tree shows excellent performance and stability for CO production (17.8 μmol g–1 h–1), almost 3 times that of pristine g-C3N4. Density functional theory computations explain the intrinsic cause for the formation of the Z-scheme structure. The enhanced photocatalytic performance can be attributed to a synergistic effect of the following factors: (1) the combination of α-Fe2O3 with g-C3N4 helps to promote light harvesting and CO2 adsorption; (2) the hybridization effectively enhances the spatial separation of photogenerated electrons and holes, suppressing the undesirable recombination of charge carriers; (3) the dendritic structure of α-Fe2O3 provides ample active sites with considerable steps, edges, and kinks along the twigs, and meanwhile, the exposed (001) facet with high electron conduction facilitates photoelectrons' transportation to the interface. This work provides new insight into constructing Z-scheme photocatalysts for CO2 conversion.