Boosting the photocatalytic H2 evolution activity of Fe2O3 polymorphs (α-, γ- and β-Fe2O3) by fullerene [C60]-modification and dye-sensitization under visible light irradiation

Abstract

C₆₀/Fe₂O₃ nanocomposites are successfully prepared, well characterized, and employed in visible-light-driven photocatalytic H₂ production. The Fe₂O₃ polymorphs show obvious broad-spectrum absorption, even close to the near infrared region (780–900 nm). The H₂ production rates of β-Fe₂O₃ and γ-Fe₂O₃ are almost 2.1 times and 3.1 times higher than α-Fe₂O₃ (which itself is close to that of g-C₃N₄). This demonstrates that carefully controlling the polymorphs can tune the photocatalysts' H₂ production properties. After modifying the Fe₂O₃ polymorphs with C₆₀, the sample with 0.5 wt% C₆₀/β-Fe₂O₃ has the optimum photocatalytic activity. This result indicates that the strength of the interaction and interfacial contact between C₆₀ and Fe₂O₃ polymorphs plays an important role in the enhancement of photocatalytic activity, which can improve the transmission efficiency of photogenerated electrons via a conjugated three-dimensional π system. Fluorescein is introduced as a photosensitizer and the optimum mass ratio of fluorescein + 0.5C₆₀/β-Fe₂O₃ is 1 : 1, which significantly boosts the photocatalytic H₂ evolution rate of 0.5C₆₀/β-Fe₂O₃ from 321.8 to 1665.0 μmol g⁻¹ h⁻¹. Meanwhile, the composites exhibit high stability and reusability.