Efficient photothermal degradation on Bi12CoO20 sillenite with a strong internal electric field induced by the thermal effect

A novel sillenite, Bi 12 CoO 20 , is reported to effectively utilize a large portion of the solar spectrum up to the Near-IR region (1000 nm), and exhibits excellent photothermal degradation. The degradation is evaluated by using phenol as the model pollutant and correlated with a temperature-induced structure change through in-situ photoelectrochemical and spectroscopic characterizations. The degradation rate on Bi 12 CoO 20 is ca. 3.0 times higher than that on P25-TiO 2 under simulated sunlight irradiation and the best by comparing with other reported photothermal catalysts. The thermal effect is demonstrated to cause the conversion of Co 3+ to Co 2+ at the octahedral sites of the Bi 12 CoO 20 , increase the internal electric field, and facilitate charge separation. The conversion also positively shifts the band potential, increasing the oxidative reactive species. The photothermal activity is newly found to be enhanced by increasing the IEF and band edge potential, which may provide strategies for designing more effective photothermal catalysts. • Bi 12 CoO 20 sillenite absorbing wavelength up to 1000 nm is successfully prepared with excellent photothermal activity. • Thermal effect induces the change of octahedral Co 3+ to Co 2+ , increases the lattice dipole and promotes charge separation. • Thermal effect tunes the band structure, enhances the oxidation potential of photogenerated holes. • Thermal and photo synergetic effect enhances the internal electric field and achieves the effective degradation.