The construction of a wide-spectrum-responsive and high-activity photocatalyst, Bi25CoO40, via the creation of large external dipoles

Currently, a major issue in the field of photocatalysis is the insufficient utilization of solar energy by photocatalysts. Thus, to overcome this problem, herein, a new sillenite photocatalyst, Bi25CoO40, was designed to exhibit a nearly full visible-light spectrum response (up to 750 nm) and high activity. In particular, its photocatalytic activity for the degradation of typical wastewater pollutants (e.g., MB and 4-CP) reached up to 3.402 h−1 for MB under visible-light irradiation and 1.576 h−1 for 4-CP under full spectrum irradiation. The degradation rates are ca. 2–4 times higher than those of well-studied photocatalysts such as P25-TiO2, Bi2WO6, and g-C3N4, and are also the best for organic pollutant removal among reported photocatalysts absorbing above 700 nm. Results showed that the remarkable degradation on Bi25CoO40 is mainly due to the efficient charge separation resulting from the large external diploe moment between [CoIIIO4] and [BiVO4] tetrahedrons. Results further illustrated that the VBM of new photocatalysts is composed of Co 3d–O 2p orbitals and exhibits a potential (ca. 2 eV) positive enough to produce oxidative species for the degradation of organic pollutants. The construction of a large external dipole moment without sacrificing the valence band edge potential may provide some design rules for the development of more efficient photocatalysts with a wide-spectrum response.