Abstract
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-TiO2 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.
NSTL