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

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.