Photocatalytic Reduction of CO₂ to C₂H₄ on Palladium-Iron-Loading Phosphorus via Promoting C-C Linking and Suppressing CO Generation.

Abstract

Photocatalytic reduction of carbon dioxide is a clean and sustainable method for carbon emission reduction. However, most of the reported photocatalysts for CO₂ reduction can produce only CO and CH₄. Phosphorus with the bandgap of 1.6 eV is a promising photocatalyst, but the slow C-C coupling efficiency renders pure phosphorus to fail to produce C2 products. Herein, we found that the iron-modified Red P photocatalyst can reduce CO₂ to C₂H₄ and C₂H₆. The yield of C₂H₄ (32.47 μmol·g^-1·h^-1) is much higher than that of CO (2.04 μmol·g^-1·h^-1), CH₄ (2.36 μmol·g^-1·h^-1). Moreover, when PdFe substitutes for Fe, no C₂H₆ is produced, the generation of C₂H₄ further increases, while CO and CH₄ are suppressed, with their yields decreasing by about 72.8 and 17.5 times, respectively. The yield of C₂H₄ increases to 44.91 μmol·g^-1·h^-1, and its selectivity of C₂H₄ increases to 99.79%, which is the highest value among state-of-the-art photocatalysts. The C-C coupling can be achieved through a "channel" between Fe atoms in the Fe-P system. This study proposes a catalyst for reducing carbon dioxide to ethylene and broadens people's understanding and application of photocatalysts.