Construction of TiO2/Ag3PO4 nanojunctions on carbon fiber cloth for photocatalytically removing various organic pollutants in static or flowing wastewater.

Plenty of power-shaped semiconductor nanomaterials have been used to photocatalytically degrade various pollutant wastewater in beakers, but they are difficult to be applied in the practical wastewater that is flowing in river or pipeline. Thus, the key to photocatalytically degrading the flowing wastewater is to develop flexible large-scale filter-membrane with high photocatalytic activity. To address the issue, with carbon fiber cloth (CFC) as the porous substrate and TiO2/Ag3PO4 as ultraviolet/visible (UV/Vis) responsed components, we reported the in-situ growth of TiO2/Ag3PO4 nanojunctions on CFC as filter-membrane-shaped photocatalyst. The resulting CFC/TiO2/Ag3PO4 is composed of CFC whose surface is decorated with TiO2 nanorods (length: 1 ± 0.5 µm, diameter: 150 ± 50 nm) and Ag3PO4 nanoparticles (diameter: 20-100 nm). CFC/TiO2/Ag3PO4 displays a broad absorption region with two edges (~410 and ~510 nm), owing to the bandgaps of TiO2 and Ag3PO4. Under Vis or UV-Vis light illumination, CFC/TiO2/Ag3PO4 (4 × 4 cm2) can efficiently degrade more phenol (80.6%/89.4%), tetracycline (TC, 91.7%/94.2%), rhodamine B (RhB, 98.4%/99.5%) and acid orange 7 (AO7, 97.6%/98.3%) in the beaker than CFC/TiO2 or CFC/Ag3PO4. Especially, CFC/TiO2/Ag3PO4 (diameter: ~10 cm) as the filter-membrane was used to construct multiple device for degrading the flowing RhB wastewater. The removal efficiency of RhB increases from 19.6% at the 1st pool to 96.8% at the 8th pool. Therefore, this study brings some insights for purifying organic pollutants in static or flowing wastewater by using filter-membrane-shaped photocatalysts.

Construction of titanium dioxide/cadmium sulfide heterojunction on carbon fibers as weavable photocatalyst for eliminating various contaminants.

Semiconductor heterojunction powders have exhibited the enhanced photocatalytic activities, but their practical applications have been limited due to their poor recycling performance from flowing wastewater. To solve these problems, with carbon fibers (CFs) as the fixing substrate, we constructed TiO2/CdS heterojunction as a model on CF surface by utilizing a hydrothermal-chemical bath deposition method. CFs/TiO2/CdS bundles display a wide photoabsorption with two photoabsorption edges (~410 and 520 nm). Furthermore, CFs/TiO2/CdS bundles can be weaved into macroscopical cloth (such as weight: 0.1 g, area: 4 × 4 cm2) which have considerable photocurrent density of 5.75 × 10-6 A/cm2. Under visible light irradiation (λ > 400 nm), macroscopic CFs/TiO2/CdS cloth can degrade 95.44% methylene blue (MB), 64.95% acid orange 7 (AO7), 91.37% tetracycline hydrochloride (TC) and remove 90.70% hexavalent chromium (Cr(VI)) after 120 min, higher than those by CFs/CdS (43.42% MB, 37.42% AO7, 31.76% TC and 30.45% Cr(VI)) or CFs/TiO2 (12.84% MB, 10.48% AO7, 11.85% TC and 15.58% Cr(VI)). Thus, CFs/TiO2/CdS can act as a weavable and efficient photocatalyst for eliminating various pollutants from wastewater.