Constructing the facet junction on solid solution BiOBr1-xClx for efficient photocatalytic CO2 reduction with H2O

Photocatalytic conversion of CO2 to renewable clean fuels was a promising way to alleviate the energy crisis and solve environmental issues. However, it remained significantly challenging for designing highly efficient photocatalysts. Herein, the solid solution BiOBr1-xClx (0 ≤ x ≤ 1, BOBC-n, n represented the amount of molten salt) with (001)/(102) facet junction was constructed through a molten salt method. In situ photochemical probing demonstrated that distinct exposed facets allowed photogenerated holes and electrons to migrate to the dominantly exposed and co-exposed facets and thus exhibited different reactivity. Benefiting from facet junction, the optimized BOBC-0.5 exhibited the superior performance of photocatalytic CO2 to CH3OH (5.52 μmol·g-1·h-1) to that of BiOBr with (001)/(110) facet junction (1.78 μmol·g-1·h-1). The density functional theory (DFT) calculations further confirmed the separation path of photogenerated carriers between distinct facets, which realized the effective spatial separation of electrons and holes. Moreover, the (102) facet revealed superior adsorption energy of CO2 molecules to that of (110) facet. This work highlighted a molten-salt strategy to build facet junction for boosting photocatalytic CO2 performance.