Enhanced Photocatalytic Activities of g-C3N4 via Hybridization with a Bi–Fe–Nb-Containing Ferroelectric Pyrochlore

Ferroelectricity may promote photocatalytic performance because the carrier-separation efficiency can be effectively improved by the internal electrostatic field caused by spontaneous polarization. Heterostructures that combine ferroelectric materials with other semiconductor materials can be further advantageous to the photocatalysis process. In this work, Bi1.65Fe1.16Nb1.12O7 was hybridized with g-C3N4 via a facile low-temperature method. The results of high-resolution transmission electron microscopy confirmed that a tight interface was formed between g-C3N4 and Bi1.65Fe1.16Nb1.12O7, which gave the (g-C3N4)–(Bi1.65Fe1.16Nb1.12O7) heterojunction a more superior visible light photocatalytic performance. The degradation of rhodamine B by optimized (g-C3N4)0.5–(Bi1.65Fe1.16Nb1.12O7)0.5 under visible light was almost 3.3 times higher than that by monomer Bi1.65Fe1.16Nb1.12O7 and 7.4 times higher than that by g-C3N4. The (g-C3N4)0.5–(Bi1.65Fe1.16Nb1.12O7)0.5 sample also showed the highest photocurrent in the photoelectrochemical tests. To further verify the benefit of the built-in electric field in terms of the photocatalytic performance, Bi2FeNbO7, with a higher spontaneous polarization, was also synthesized and hybridized with g-C3N4. Both Bi2FeNbO7 and (g-C3N4)0.5–(Bi2FeNbO7)0.5 exhibited better photocatalytic activities than those of Bi1.65Fe1.16Nb1.12O7 and (g-C3N4)0.5–(Bi1.65Fe1.16Nb1.12O7)0.5, although the latter ones had a stronger visible-light absorbance. This implies the very promising prospects of applying ferroelectric materials for solar energy harvest.