Abstract
Titanium dioxide (TiO2) as an important semiconductor is widely used in the fields of solar cell, solar thermal collectors, and photocatalysis, but the visible-light power harvest remains insufficient due to the little effective visible-light absorption and many carrier-recombination centers originating from the wide band gap structure. Herein, conductive black titania (BT) nanomaterials with crystalline-TiO2-core/amorphous-TiO2−x-shell structure prepared through two-zone Al-reduction route are found efficient in photocatalyzing the degradation of organic pollutants to environmentally friendly products under full solar and even visible light irradiation. The unique core–shell structure and numerous surface oxygen vacancies or Ti3+ species in the amorphous layer accompanying prominent physicochemical properties of narrow band gap, high carrier concentration, high electron mobility, and excellent separation and transportation of photoinduced e−−h+ pairs result in exceptional photocatalytic efficiency. The optimized BT-500 (pristine TiO2 treated at 500 °C during two-zone Al-reduction process) catalyst achieves superior photocatalytic degradation rates for toluene and ethyl acetate as well as an excellent photostability with high degradation efficiency of 93% for the 6th reuse.Graphic
Highlights
Toxic organic pollutants, like hydrocarbons, esters, aldehydes, and phenols, emitted from chemical industries and modern life can lead to serious environmental pollution and health issues [1, 2]
It should be emphasized that there is no Al element in the final black titania (BT) samples, as proved by X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) analysis in Fig. S4. TiO2 powder was converted from white to gray of BT-300 and darkblue of BT-400 and black of BT-500 by increasing the reduction temperature, suggesting that the enhanced Vis-light absorption for dark color samples [33]
Efficient conductive black titania nanomaterisls with typical crystalline-TiO2-core/amorphous- TiO2−x-shell structure were successfully fabricated by using two-zone Al-reduction strategy
Summary
Like hydrocarbons, esters, aldehydes, and phenols, emitted from chemical industries and modern life can lead to serious environmental pollution and health issues [1, 2]. To narrow the intrinsic band gap and extend the response region of T iO2 to the Vis or IR light, large number of elements are doped to obtain colourful materials [10–15, 17, 18] These strategies show little improvement in aspect of the catalytic efficiency owing to the enhanced recombination rate of photogenerated electrons and holes, and low carrier concentrations. The key to the successful use of the designed photocatalysts is the unique crystalline-core/amorphous-shell structure and numerous surface Vo showing narrow band gap, high carrier concentration, prominent electron mobility, and excellent separation and transportation of photoinduced e −−h+ pairs. These special physicochemical properties of series BT samples favor efficient adsorption, chemical activation, and photocatalytic oxidation transformation of organic pollutant molecule. The present findings are promising for offering an effective photocatalyst system for degradation of toxic organic pollutants to environmentally friendly products, and for obtaining novel insights into colored titania catalyzed reactions
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