CO₂-initiated epitaxial growth fabrication of 2D facet-coupled Bi₂O₂CO₃/ BiOIO₃ vertical heterostructure for highly-efficiency CO₂-to-CO photocatalysis

Epitaxial heterostructures, in particular those 2D vertical heterostructures with close face-to-face contact, are appealing candidates for photocatalytic CO2 reduction. Usually, precise control of the growth rate and a seed nanosheet having a small lattice mismatch with the overlayer is essential for the realization of epitaxial growth. Here we present a CO2-initiated solution-phase epitaxial growth strategy to directly fabricate 2D facet-coupled vertical heterostructures without a seed-layer assistant, in which supercritical CO2 liquid can not only manipulate the nucleation and growth of BiOIO3 to match with the epitaxial growth of the Bi2O2CO3 layer, but also provide better wetting conditions to minimize the interfacial energy, thus facilitating the 2D layer-by-layer growth. The obtained heterostructures exhibit the highest CO2-to-CO conversion rate of 224.71 mu mol g-1 h-1 in pure water. These findings open up a new platform for highly controlled epitaxial growth of heterostructures.