A simple green approach to synthesis of sub-100 nm carbon spheres as template for TiO2 hollow nanospheres with enhanced photocatalytic activities

Abstract

Carbon spheres (CSs) have attracted great attention given their wide applications in bio-diagnostics, photonic band-gap crystals and drug delivery, etc. The morphology and size of CSs greatly affect their performances and applications. Herein, we report a green and catalyst-free hydrothermal carbonization (HTC) method to synthesize CSs with glucose as carbon precursor. The diameter of CSs can be tuned within a wide range from 450 to 40 nm by controlling the glucose concentration, reaction time and temperature. Using the obtained CSs as template, hollow TiO 2 nanospheres (HTNSs) with controllable diameters are prepared via a sol-gel method. As photocatalysts for hydrogen generation, the photoactivity of the HTNSs shows strong dependence upon size, and is much higher than that of solid TiO 2 . With particle size decreasing, the photoactivity of the obtained HTNSs gradually increases. Without any co-catalyst, the highest photocatalytic hydrogen generation activity is obtained with HTNSs of 40 nm in diameter, which exceeds that of solid TiO 2 and commercial P25 by 64 times and 3 times, respectively.

Recent Advances in Photocatalysis Based on Bioinspired Superwettabilities

“…What is more, the superhydrophobic photocatalytic efficiency still remained stable even after 20 cycles (Figure 7e). Taking advantage of these air−water−solid triphase systems, researchers fabricated a series of photocatalytic platforms for H 2 generation, 192,193 organic photodegradation, 194,195 and H 2 O 2 generation. 196,197 Due to superhydrophobicity, self-cleaning on a photocatalyst was enhanced due to the synergistic effect of strong water repellency and photocatalytic activity, 186−190 where the rolling drops remove macroscopic dirt and photocatalysis is induced by UV or solar light to ensure the photodegradation of organic pollution.…”

“…What is more, the superhydrophobic photocatalytic efficiency still remained stable even after 20 cycles (Figure e). Taking advantage of these air–water–solid triphase systems, researchers fabricated a series of photocatalytic platforms for H 2 generation, , organic photodegradation, , and H 2 O 2 generation. , …”

Carbon Sphere Template Derived Hollow Nanostructure for Photocatalysis and Gas Sensing

“…Although the hydrothermal carbonization (HTC) method for carbon spheres is mature and widely used, there exist some limitations that restrict the formation of relatively small size of carbon sphere. Tan et al [36] finally overcome this barrier by varying parameters of hydrothermal carbonization process-including glucose concentration, pH value, and temperature-and synthesize small-sized carbon spheres (40 nm) for the first time.…”

“…Although the hydrothermal carbonization (HTC) method for carbon spheres is mature and widely used, there exist some limitations that restrict the formation of relatively small size of carbon sphere. Tan et al [36] finally overcome this barrier by varying parameters of hydrothermal carbonization process-including glucose concentration, pH value, and temperature-and synthesize small-sized carbon spheres (40 nm) for the first time. A typical hydrothermal synthesis for carbon sphere template consists of 5g glucose dissolving in 30 ml water, sealing in a 50 mL autoclave and maintaining at 180 ℃ for 6 h. The as-prepared templates were isolated by several rinsing-centrifugation cycles until the solution is clear and ovendried.…”

Construction of Indium Oxide/N-Doped Titanium Dioxide Hybrid Photocatalysts for Efficient and Selective Oxidation of Cyclohexane to Cyclohexanone

“…Titanium dioxide (TiO 2 ), with chemical stability, low price, and nontoxicity, has attracted considerable attention in the photo-oxidation of CHA. − However, bare TiO 2 possesses some intrinsic defects (e.g., low sunlight use efficiency, fast recombination of photoformed carrier, low quantum efficiency, etc. ), − which greatly affect the photocatalytic efficiency to confine its actual use in the photo-oxidation of CHA. The TiO 2 modified with other beneficial materials has been considered as one of the most effective strategy to improve the light harvesting efficiency and photocatalytic performance. − The photo-oxidation of CHA has become a hotspot with TiO 2 -based hybrid catalysts for enhancing the reaction even at atmospheric pressure and room temperature. − However, the enhancement of activity and CHA-one selectivity is necessary for the photo-oxidation of CHA with TiO 2 -based catalysts because it is insufficient right now.…”