Perovskite Photocatalytic CO2 Reduction or Photoredox Organic Transformation?

Metal-halide perovskites have been explored as photocatalysts for CO₂ reduction. We report that perovskite photocatalytic CO₂ reduction in organic solvents is likely problematic. Instead, the detected products (i.e., CO) likely result from a photoredox organic transformation involving the solvent. Our observations have been validated using isotopic labeling experiments, band energy analysis, and new control experiments. We designed a typical perovskite photocatalytic setup in organic solvents that led to CO production of up to ≈1000 μmol g⁻¹ h⁻¹. CO₂ reduction in organic solvents must be studied with extra care because photoredox organic transformations can produce orders of magnitude higher rate of CO or CH₄ than is typical for CO₂ reduction routes. Though CO₂ reduction is not likely to occur, in situ CO generation is extremely fast. Hence a suitable system can be established for challenging organic reactions that use CO as a feedstock but exploit the solvent as a CO surrogate.