The α-Fe
2
O
3
/g-C
3
N
4
heterojunction was synthesized using a facile ultrasonic method using alpha hematite (α-Fe
2
O
3
) and graphitic carbon nitrite (g-C
3
N
4
) as precursors. These samples ...were characterized by advanced techniques such as SEM, EDX, XRD, PL and UV-Vis to investigate their morphology, elemental composition, crystalline structures and optical properties. Photocatalytic performance of these synthesized materials was investigated via degradation of tetracycline in the aqueous environment upon excitation of visible light. Obtained experimental results indicated that the synthesized α-Fe
2
O
3
/g-C
3
N
4
sample exhibited high photocatalytic activity for tetracycline degradation. The improvement in photocatalytic efficiency of the synthesized α-Fe
2
O
3
/g-C
3
N
4
was due to the Z-scheme mechanism, which effectively prevented electron-hole recombination or increased electron-hole separation efficiency for photocatalysis. The photocatalytic tetracycline degradation by the α-Fe
2
O
3
@g-C
3
N
4
followed the pseudo first-order model. The optimized pH for its photocatalysis was found to be 8. Finally, the synthesized material exhibited high stability after five recycling cycles.
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•Successfully doped V into TaON lattice to enhance its photocatalytic activity.•V dopant enhanced e−/h+ separation and prolonged the lifetime of the generated e− and h+.•The VTaON ...converted CO2 into CH4 and CO even under visible light.•The optimal V doping ratio enhancing photocatalytic activity of TaON was 1.5 wt%.
We successfully used V as dopant to enhance activity of TaON for visible light photocatalytic reduction of CO2 into valuable fuels. We investigated that the used V dopants existed in the TaON lattice and replaced several Ta elements in the lattice leading to decrease in the conduction band minimum and increase in the valence band maximum of the prepared VTaON. Hence, the band gap energy of the prepared VTaON was lower than that of prepared TaON or the prepared VTaON material could absorb significant amount of incident visible light for production of e− and h+ pairs, which participated in reactions with CO2 and H2O to generate CH4, CO, O2 and H2. We also investigated that the optimal V/Ta ratio (or optimal amount of V dopant) for maximum enhancing photocatalytic activity of TaON was 1.5 wt%. The prepared 1.5VTaON visible light photocatalytically converted CO2 with H2O to generate CH4, CO, O2 and H2 with generation rates of 673, 206, 1479 and 67 (µmol·g−1cat·h−1), respectively.
In this study, titanium (Ti) was used as an active dopant to incorporate into BiVO4 lattice using the hydrothermal method. The synthesized BiVO4 and Ti–BiVO4 with 1, 5 and 10 wt% of Ti dopants have ...been applied for photocatalytic decomposition of Tetracycline under visible light irradiation. The characterized results showed that this synthesized BiVO4 and Ti–BiVO4 materials existed in a form of spherical particles. The particle sizes of the Ti–BiVO4 were much bigger than that of the BiVO4. However, Ti dopants effectively enhanced visible light absorption, decreased band gap energy as well as prevented electron-hole recombination of the BiVO4 leading to increase in photocatalytic activities of the doped materials. The obtained results from photocatalytic experiments indicated that the 5Ti–BiVO4, whose weight ratio of Ti was 5%, was the best material for TC degradation (78.49%). Recycling tests were consecutively carried out in 4 runs to demonstrate the stability of the BiVO4 photocatalyst with 5 wt% of Ti dopant.
In this study, InVO4 was effectively hybridized with g-C3N4 to create InVO4/g-C3N4 Z-scheme heterojunction. Ag metals were also successfully decorated on the InVO4/g-C3N4 to further improve its ...photocatalytic performance for tetracycline degradation. Scavenger experiments were conducted to investigate photocatalytic degradation mechanism of the synthesized materials. The characterization and experimental results showed that InVO4 and g-C3N4 would absorb incident visible light to induce electrons to their conduction band (CB) leaving holes at their valence band (VB). Then, photo-induced electrons in the InVO4 CB would move to the g-C3N4 VB to recombine with its holes leading to preservation of photo-induced electrons at the g-C3N4 CB, which has high reduction potential, and holes in the InVO4 VB, which has high oxidation potential, for effective degradation of tetracycline. When Ag metals were decorated on InVO4/g-C3N4, plasmon resonance of Ag would effectively increase light absorption and induce electron-hole separation of the InVO4 as well as the g-C3N4. The decorated Ag also acted as charge mediator to enhance electron transfer from the InVO4 CB and the g-C3N4 VB to improve electron-hole separation or photocatalytic efficiency of the InVO4/g-C3N4. Therefore, the Ag decorated on InVO4/g-C3N4 (AIC) presented novel photocatalytic performance for degradation of tetracycline. Finally, the regenerating experiment results indicated that the AIC could be effectively regenerated after being used.
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•Successfully established InVO4/g-C3N4 Z-scheme heterojunction.•Successfully decorated Ag on InVO4/g-C3N4 to further enhance its photocatalytic activity.•The Ag decorated on InVO4/g-C3N4 showed novel photocatalytic activity for TC degradation.•The synthesized photocatalyst exhibited novel stability and regenerating ability.
In the study, we doped N into TiO2 lattice to narrow its band gap energy. Then, the synthesized N doped TiO2 material was combined with AgI to form AgI/N–TiO2 (ANT) direct Z scheme materials. The ...synthesized materials were utilized for photocatalytic removal of tetracycline (TC) using visible irradiation as an excitation source. We also conducted radical scavenging experiments to determine photocatalytic degradation mechanism. We investigated that these photo-excited electrons (e−) in N–TiO2 conduction band tended to combine with the left holes (h+) in AgI valence band maintaining h+ in the valence band of the N–TiO2 and e− in the conduction band of the AgI. The remained e− and h+ have high redox potential to initiate for photocatalytic decomposition of TC. Thus, the TC degradation by the ANT materials were significant greater than those by single components (AgI or N–TiO2). We also investigated that the TC degradation by the ANT-30 material, which the AgI: N–TiO2 molar ratio was 30%, exhibited that highest degradation efficiency. Finally, the ANT photocatalyst exhibited excellent stability during TC degradation processes supporting for its promising potential application in practical systems.
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•Synthesized Ta3N5 and V–Ta3N5 successfully converted CO2 to valuable fuels.•V dopant enhanced electron–hole separation and prolonged its lifetime.•V–Ta3N5 exhibited great increases ...in light adsorption and decreases in band gap energy.•V–Ta3N5 reduced CO2 and H2O vapor to CH4, CO, O2, and H2 even under visible light.•A V/Ta ratio of 2wt.% was optimal for enhancing the photocatalytic activity of Ta3N5.
In this study, Ta3N5 and V-doped Ta3N5 (V–Ta3N5) were synthesized as catalysts for the conversion of CO2 into valuable fuels under visible light. As compared with Ta2O5, the synthesized Ta3N5 and V–Ta3N5 exhibited great increases in visible light adsorption and decreases in band gap energy. Therefore, the synthesized Ta3N5 and V–Ta3N5 photocatalytically converted CO2 into CO and CH4 even under visible light. The V dopants, which existed in the Ta3N5 lattice, could act as an intermediate band (V3d) between the valence band (N2p) and the conduction band (Ta5d) of the Ta3N5 to increase the electron–hole separation efficiency of the photocatalyst. Thus, the photocatalytic activity of V–Ta3N5 was much higher than that of Ta3N5. However, an increase in the V doping ratio led the formation of VN particles distributed on the Ta3N5 surface. The formed particles eclipsed the light reaching the photocatalyst surface, resulted in a decrease in photocatalytic activity. The optimal V doping ratio in V–Ta3N5 was found to be 2wt.%. As a result, the production rates of CH4, CO, O2, and H2 generated from the photocatalytic reduction of CO2 by 2wt.% V–Ta3N5 under visible light were 425, 236, 1003, and 56µmolg−1cath−1, respectively.
Vietnam has high rates of antibiotic use and resistance. Measuring resistance in commensal bacteria could provide an objective indicator for evaluating the impact of interventions to reduce ...antibiotic use and resistance. This study aimed to evaluate the feasibility, acceptability, and bacterial recovery for different sampling strategies. We conducted a cross-sectional mixed methods study in a rural community in Ha Nam Province, northern Vietnam, and collected structured interviews, samples, and in-depth interviews from households. Out of 389 households invited, 324 participated (83%), representing 1502 individuals. Samples were collected from these individuals (1498 stool, 1002 self-administered nasal swabs, and 496 HW-administered nasopharyngeal swabs). Pneumococci were recovered from 11.1% (128/1149) of the total population and 26.2% (48/183) of those under 5-years. Recovery was higher for health-worker (HW)-administered swabs (13.7%, 48/350) than self-administered swabs (10.0%, 80/799) (OR 2.06, 95% CI 1.07-3.96). Cost per swab was cheaper for self-administered ($7.26) than HW-administered ($8.63) swabs, but the overall cost for 100 positive samples was higher ($7260 and $6300 respectively). Qualitative interviews revealed that HW-administered nasopharyngeal swabs took longer to collect, caused more discomfort, and were more difficult to take from children. Factors affecting participation included sense of contribution, perceived trade-offs between benefits and effort, and peer influence. Reluctance was related to stool sampling and negative perceptions of research. This study provides important evidence for planning community-based carriage studies, including cost, logistics, and acceptability. Self-administered swabs had lower recovery, and though cheaper and quicker, this would translate to higher costs for large population-based studies. Recovery might be improved by swab-type, transport medium, and better cold-chain to lab.
In the study, rGO was used as an electron mediator to establish WO3@rGO@AgI (WrGA) ternary heterojunction to apply for degradation of Amoxil upon excitation of visible light. Various characterization ...methods and technologies, such as XRD, SEM, TEM, UV–Vis and PL, and trapping experiments of active species were applied to determine charge separation as well as degradation mechanism. The achieved data showed that both WO3 and AgI in the synthesized WrGA had suitable band gap energies to absorb provided visible light for e− jumping from valence band (VB) to conduction band (CB) leaving h+ at the VB. Then, the rGO effectively acted as e− mediator to promote Z scheme mechanism for its migration from the WO3 CB to the AgI VB to prevent charge recombination in WO3 as well as AgI. The charge separation via Z scheme mechanism also maintained significant charges (e− at AgI CB and h+ at WO3 VB) with high redox potentials for photocatalysis. Therefore, the Amoxil degradation efficiency of the WrGA was 24% higher than that of the WA (without rGO). Finally, the recycling tests showed novel stability and recycling potential of the synthesized WrGA opening new era for its application in practical system for degradation of organic pollutants.
In the study, we used two conducting polymers, polyaniline (PANI) and polypyrrole (PPy), to sensitize Ta3N5, thereby enhancing its photocatalytic activity, and then applied this novel photocatalyst ...to overall water splitting to produce hydrogen and oxygen even under visible light irradiation. The two polymers increased the charge transfer efficiency, prevented the recombination of the generated electrons and holes of the Ta3N5 photocatalyst, and thereby enhanced its electron-hole separation efficiency and improved its photocatalytic activity for efficient visible light water splitting. The two polymers completely covering the Ta3N5 particles facilitated charge transfer for quick migration of the generated electrons and holes to the polymer surface and thus prevented contact between the holes and nitride of Ta3N5. Therefore, these conducting polymers also protected the Ta3N5 particles from self-photocorrosion during long-term water splitting. Because of the existence of the protonated nitrogen (-N+) state in PPy, the electric conductivity of PPy was lower than that of PANI, which lowered the sensitizing ability of PPy compared to that of PANI. Thus, the water splitting efficiency of Ta3N5/PANI was higher than that of Ta3N5/PPy. The production rates of H2 and O2 generated from water splitting of Ta3N5/PANI were 60.5 and 30.2 (μmol. g−1cat. h−1), respectively.
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•Polymer sensitizers enhanced the separation of e−/h+ pairs and prolonged the Ta3N5 lifetime.•Polymer cover protected Ta3N5 from self-photocorrosion (oxidation of generated holes).•Ta3N5/polymers greatly exhibited overall photocatalytic water splitting.•Lower electric conductivity lowered the sensitizing ability of the polymer.•PANI was better than PPy for enhancing the photocatalytic activity of Ta3N5.
Polyaniline (PANI) and polythiophene (PTh) conducting polymers have been used to sensitize Tantalum Nitride (Ta3N5) to enhance its photocatalytic activity. The synthesized materials exhibited novel ...photocatalytic activity for overall water splitting to produce hydrogen and oxygen even excited by visible light irradiation. The used PANI and PTh sensitizers enhanced the charge transfer efficiency and minimized the high recombination rate of the photo-excited electrons (e-) and holes (h+) of the Ta3N5 photocatalyst (enhanced e-/h+ separation efficiency of the Ta3N5) leading to increase in its photocatalytic activity for efficient visible light water splitting. We also investigated that the used PANI and PTh completely covering the Ta3N5 particles could acted as charge acceptors for quick migration of the produced h+ to their surface and thus minimizing contact between the nitride of the Ta3N5 and the produced h+, which could oxidize the nitride. It means that the used conducting polymers also protected the Ta3N5 particles from self-photocorrosion. Therefore, the synthesized tantalum nitride sensitized/protected by PANI or PTh could be applied for long-term water splitting. The production rates of H2 and O2 generated from water splitting of Ta3N5/PANI were higher than that of the Ta3N5/PTh because the electric conductivity of the PANI was higher than that of the PTh.
Sensitizing and protecting mechanism of used conducting polymers. Display omitted
•PANI and PTh enhanced the e- and h+ separation efficiency of the Ta3N5.•PANI and PTh also protected Ta3N5 from self-photocorrosion (oxidation of produced h+).•Ta3N5/polymers showed superior overall photocatalytic water splitting.•The electric conductivity positive related to sensitizing ability of the polymer.•The photocatalytic activity of the Ta3N5/PANI was better than that of the Ta3N5/PTh.
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