Utilizing the oxygen-atom trapping effect of Co3O4 with oxygen vacancies to promote chlorite activation for water decontamination.

Heterogeneous high-valent cobalt-oxo [≡Co(IV)=O] is a widely focused reactive species in oxidant activation; however, the relationship between the catalyst interfacial defects and ≡Co(IV)=O formation remains poorly understood. Herein, photoexcited oxygen vacancies (OVs) were introduced into Co3O4 (OV-Co3O4) by a UV-induced modification method to facilitate chlorite (ClO2-) activation. Density functional theory calculations indicate that OVs result in low-coordinated Co atom, which can directionally anchor chlorite under the oxygen-atom trapping effect. Chlorite first undergoes homolytic O-Cl cleavage and transfers the dissociated O atom to the low-coordinated Co atom to form reactive ≡Co(IV)=O with a higher spin state. The reactive ≡Co(IV)=O rapidly extracts one electron from ClO2- to form chlorine dioxide (ClO2), accompanied by the Co atom returning a lower spin state. As a result of the oxygen-atom trapping effect, the OV-Co3O4/chlorite system achieved a 3.5 times higher efficiency of sulfamethoxazole degradation (~0.1331 min-1) than the pristine Co3O4/chlorite system. Besides, the refiled OVs can be easily restored by re-exposure to UV light, indicating the sustainability of the oxygen atom trap. The OV-Co3O4 was further fabricated on a polyacrylonitrile membrane for back-end water purification, achieving continuous flow degradation of pollutants with low cobalt leakage. This work presents an enhancement strategy for constructing OV as an oxygen-atom trapping site in heterogeneous advanced oxidation processes and provides insight into modulating the formation of ≡Co(IV)=O via defect engineering.

Efficient Photothermal Catalytic Oxidation Enabled by Three-Dimensional Nanochannel Substrates.

Photothermal catalysis exhibits promising prospects to overcome the shortcomings of high-energy consumption of traditional thermal catalysis and the low efficiency of photocatalysis. However, there is still a challenge to develop catalysts with outstanding light absorption capability and photothermal conversion efficiency for the degradation of atmospheric pollutants. Herein, we introduced the Co3O4 layer and Pt nanoclusters into the three-dimensional (3D) porous membrane through the atomic layer deposition (ALD) technique, leading to a Pt/Co3O4/AAO monolithic catalyst. The 3D ordered nanochannel structure can significantly enhance the solar absorption capacity through the light-trapping effect. Therefore, the embedded Pt/Co3O4 catalyst can be rapidly heated and the O2 adsorbed on the Pt clusters can be activated to generate sufficient O2- species, exhibiting outstanding activity for the diverse VOCs (toluene, acetone, and formaldehyde) degradation. Optical characterization and simulation calculation confirmed that Pt/Co3O4/AAO exhibited state-of-the-art light absorption and a notable localized surface plasmon resonance (LSPR) effect. In situ diffuse reflectance infrared Fourier transform spectrometry (in situ DRIFTS) studies demonstrated that light irradiation can accelerate the conversion of intermediates during toluene and acetone oxidation, thereby inhibiting byproduct accumulation. Our finding extends the application of AAO's optical properties in photothermal catalytic degradation of air pollutants.

Comparison of the effectiveness of BG-trap mosquito traps using carbon dioxide versus BG-lure attractants / 中国热带医学

@#Abstract: Objective　To compare the mosquito trapping effect of BG-trap mosquito trap using carbon dioxide versus BG-lure attractant under filed conditions. Methods　In August and September 2020, two areas were set with a distance of 100 m. Two sites were set at each area, and one mosquito trap BG trap was set with a distance of 5 m. Each site was set with different flow of CO2 and different amount of BG-lure attractants. The BG-trap mosquito traps on the same area would exchange positions every other day. The mosquitoes captured by each mosquito trap was collected and classified. and the species, sex and number of mosquitoes captured were recorded and counted. Results　The densities of Aedes albopictus captured by BG+/CO2-and BG-/CO2+were 14 and 31, and that of Culex pipiens pallens were 2 and 16, respectively. The differences were statistically significant (Aedes albopictus, t=-2.675, P<0.05; Culex pipiens pallens, t=-4.873, P<0.05). With BG-lure attractant, the females of Aedes albopictus and Culex pipiens pallens in the CO2+group were 2.6 (25/9.5) and 12.0 (12 /1) times higher than those in the CO2-group, and the differences were statistically significant (female Aedes albopictus, t=-4.119, P<0.01; female Culex pipiens pallens, t=-4.592, P<0.01), suggesting that the most important attractant to female mosquitoes is CO2. With BG-lure attractant, the male Aedes albopictus in the CO2+ group was 3.0 (12/4) times higher than that in the CO2-group, and the difference was statistically significant (male Aedes albopictus, t=-3.284, P<0.01). Without BG-lure attractant, female Aedes albopictus and female Culex pipiens pallens in the CO2 + group were 1.8 (18 / 10) and 15.5 (15.5/1.0) times higher than those in the CO2-group, and the difference was statistically significant (female Aedes albopictus, t=-2.868, P<0.05; female Culex pipiens pallens, t=-5.259, P<0.05). Without BG-lure attractant, the male Aedes albopictus in the CO2+group was 2.0 (9.0/4.5) times higher than that in the CO2-group, with a statistically significant difference (t=-2.508, P<0.05). With CO2, Aedes albopictus and Culex pipiens pallens in the BG + attractant group were 1.4 (43.5/31) and 0.78 (12.5/16.0) times higher than those in the BG-attractant group, and the differences were not statistically significant (Aedes albopictus, t=-0.943, P>0.05 ; Culex pipiens pallens, t=0.709, P>0.05). Without CO2, Aedes albopictus and Culex pipiens pallens in the BG + attractant group were 1.0 (14/14) and 2.0 (2.0/1.0) times higher than those in the BG + attractant group, and the differences were not statistically significant (Aedes albopictus, t=-0.500, P>0.05; Culex pipiens pallens, t=-1.000, P>0.05). Without BG-lure attractant, the densities of female Aedes albopictus captured by adding 0, 1 and 2 parts of dry ice were 10, 17.5 and 18 respectively, and the difference was statistically significant among the three groups (F=3.942, P<0.05). The densities of female Culex pipiens pallens captured were 1, 13 and 18 respectively, and the difference was statistically significant among the three groups (F=13.881, P<0.05). However, there was no significant difference between the capture of female Aedes albopictus and female Culex pipiens pallens by adding 1 part of dry ice and 2 parts of dry ice (female Aedes albopictus, t=0.112, P>0.05; female Culex pipiens pallens, t=-0.540, P>0.05). Without CO2, 10, 10, 9.5 and 1, 1 and 1.5 female Aedes albopictus and Culex pipiens pallens were captured by adding 0, 1 and 2 portions of BG-lure attractants, respectively. There were no significant differences between the three groups (female Aedes albopictus, F=0.120, P>0.05; female Culex pipiens pallens, F=0.477, P>0.05). Conclusions　In the monitoring of BG-trap mosquito trap, the mosquito trapping effect of CO2 is better than that of BG-lure attractant. When the same monitoring effect is obtained, the use of CO2 (100 mL/min) can save the use cost.