scholarly journals Visible-Light Driven TiO2 Photocatalyst Coated with Graphene Quantum Dots of Tunable Nitrogen Doping

Molecules ◽  
2019 ◽  
Vol 24 (2) ◽  
pp. 344 ◽  
Author(s):  
Xiong Sun ◽  
Hui-Jun Li ◽  
Nanquan Ou ◽  
Bowen Lyu ◽  
Bojie Gui ◽  
...  

Nitrogen doped graphene quantum dots (NGQDs) were successfully prepared via a hydrothermal method using citric acid and urea as the carbon and nitrogen precursors, respectively. Due to different post-treatment processes, the obtained NGQDs with different surface modifications exhibited blue light emission, while their visible-light absorption was obviously different. To further understand the roles of nitrogen dopants and N-containing surface groups of NGQDs in the photocatalytic performance, their corresponding composites with TiO2 were utilized to degrade RhB solutions under visible-light irradiation. A series of characterization and photocatalytic performance tests were carried out, which demonstrated that NGQDs play a significant role in enhancing visible-light driven photocatalytic activity and the carrier separation process. The enhanced photocatalytic activity of the NGQDs/TiO2 composites can possibly be attributed to an enhanced visible light absorption ability, and an improved separation and transfer rate of photogenerated carriers.

RSC Advances ◽  
2020 ◽  
Vol 10 (60) ◽  
pp. 36930-36940 ◽  
Author(s):  
Petri M. Leukkunen ◽  
Ekta Rani ◽  
Assa Aravindh Sasikala Devi ◽  
Harishchandra Singh ◽  
Graham King ◽  
...  

Robust photocatalytic activity of Ni–Ag–RTiO2 is attributed to the improved visible light absorption and effective charge separation due to intimate contact between Ni and RTiO2via Ag, as evidenced by Ti3+ in Ti 2p XPS and energy dispersive mapping.


RSC Advances ◽  
2016 ◽  
Vol 6 (85) ◽  
pp. 82409-82416 ◽  
Author(s):  
Ping Wu ◽  
Guoming Wang ◽  
Ruizhi Chen ◽  
Yixin Guo ◽  
Xueming Ma ◽  
...  

[KNbO3]1−x[BaNi0.5Nb0.5O3−δ]x were synthesized by Pechini sol–gel method at low temperature. Visible light photocatalytic performance of this material was evaluated.


RSC Advances ◽  
2017 ◽  
Vol 7 (63) ◽  
pp. 40028-40033 ◽  
Author(s):  
Hao Xu ◽  
Zhixing Gan ◽  
Weiping Zhou ◽  
Zuoming Ding ◽  
Xiaowei Zhang

Insufficient visible light absorption and fast recombination of the photogenerated electron–hole pairs have seriously hampered the photocatalytic performance of graphitic carbon nitride (g-C3N4) up to now.


2019 ◽  
Vol 48 (10) ◽  
pp. 3486-3495 ◽  
Author(s):  
Juying Lei ◽  
Bin Chen ◽  
Weijia Lv ◽  
Liang Zhou ◽  
Lingzhi Wang ◽  
...  

An inverse opal TiO2/g-C3N4 composite with excellent photogenerated electron–hole separation efficiency and enhanced visible light absorption efficiency was constructed.


2020 ◽  
Vol 10 (20) ◽  
pp. 6800-6808
Author(s):  
Mier Wang ◽  
Changzheng Fan ◽  
Shuaijun Yang ◽  
Milan Liu ◽  
Jun Luo ◽  
...  

The narrow visible-light absorption range and a high recombination rate of photo-excited electrons and holes are the main reasons for the confined photocatalytic performance of graphitic carbon nitride (g-C3N4).


RSC Advances ◽  
2015 ◽  
Vol 5 (123) ◽  
pp. 101552-101562 ◽  
Author(s):  
Zhao Mo ◽  
Xiaojie She ◽  
Yeping Li ◽  
Liang Liu ◽  
Liying Huang ◽  
...  

The visible light absorption of g-C3N4 was extended through controlling the synthesis temperature, and thus enhanced visible/UV photocatalytic activity. Moreover, g-C3N4 can also be used as a photoelectrochemical sensor.


Author(s):  
David Maria Tobaldi ◽  
Luc Lajaunie ◽  
ana caetano ◽  
nejc rozman ◽  
Maria Paula Seabra ◽  
...  

<div>Titanium dioxide is by far the most utilised semiconductor material for photocatalytic applications. Still, it is transparent to visible-light. Recently, it has been proved that a type-II band alignment for the rutile−anatase mixture would improve its visible-light absorption.</div><div>In this research paper we thoroughly characterised the real crystalline and amorphous phases of synthesised titanias – thermally treated at different temperatures to get distinct ratios of anatase-rutile-amorphous fraction – as well as that of three commercially available photocatalytic nano-TiO2. </div><div>The structural characterisation was done via advanced X-ray diffraction method, namely the Rietveld-RIR method, to attain a full quantitative phase analysis of the specimens. The microstructure was also investigated via an advanced X-ray method, the whole powder pattern modelling. These methods were validated combining advanced aberration-corrected scanning transmission microscopy and high-resolution electron energy-loss spectroscopy. The photocatalytic activity was assessed in the liquid- and gas-solid phase (employing rhodamine B and 4-chlorophenol, and isopropanol, respectively, as the organic substances to degrade) using a light source irradiating exclusively in the visible-range.</div><div>Optical spectroscopy showed that even a small fraction of rutile (2 wt%) is able to shift to lower energies the apparent optical band gap of an anatase-rutile mixed phase. But is this enough to attain a real photocatalytic activity promoted by merely visible-light?</div><div>We tried to give a reply to that question.</div><div>Photocatalytic activity results in the liquid-solid phase showed that a high surface hydroxylation led to specimen with superior visible light-induced catalytic activity (i.e. dye and ligand-to-metal charge transfer complexes sensitisation effects). That is: not photocatalysis <i>sensu-strictu</i>.</div><div>On the other hand, the gas-solid phase results showed that a higher amount of the rutile fraction (around 10 wt%), together with less recombination of the charge carriers, were more effective for an actual photocatalytic oxidation of isopropanol.</div>


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