Amorphous TiO2 beats P25 in visible light photo-catalytic performance due to both total-internal-reflection boosted solar photothermal conversion and negative temperature coefficient of the forbidden bandwidth

In this work, visible light total reflective SiO2 @TiO2 core-shell catalyst was synthesized by atomic layer deposition (ALD). This core-shell catalyst processing a total reflection character against full visible light favors the total effective traveling length of visible light inside the TiO2 shell. Subsequently, higher catalyst temperature under visible light irradiation expands the light absorbing window of amorphous TiO2 to full visible light due to its negative temperature coefficient of the forbidden bandwidth. Boosted photothermal conversion efficiency (145% that of amorphous TiO2) can be achieved to exhibit a 17 beta-estrogen degradation rate 1.5 times that of the commercial P25 (a mixed TiO2 crystal of 20% rutile and 80% anatase) and 2.9 times catalytic velocity that of P25. The boosted catalytic performance of SiO2 @TiO2 core-shell catalyst is attributed by expanded visible-light absorption, boosted photothermal conversion efficiency, and prolonged carrier lifetime.