Overcoming the Interfacial Photocatalytic Degradation of Nonfullerene Acceptor-Based Organic Photovoltaics by Introducing a UV-A-Insensitive Titanium Suboxide Layer

Although recent dramatic advances in power conversion efficiencies (PCEs) have resulted in values over 19%, the poor photostability of organic photovoltaics (OPVs) has been a serious bottleneck to their commercialization. The photocatalytic effect, which is caused by incident ultraviolet-A (UV-A, 320-400 nm) light in the most commonly used zinc oxide (ZnOX) electron transport layer (ETL), significantly deteriorates the photostability of OPVs. In this work, we develop a new and facile method to enhance the photostability of nonfullerene acceptor-based OPVs by introducing UV-A-insensitive titanium suboxide (TiOX) ETL. Through an in-depth analysis of mass information at the interface between the ETL and photoactive layer, we confirm that the UV-A-insensitive TiOX suppresses the photocatalytic effect. The resulting device employing the TiOX ETL shows excellent photostability, obtaining 80% of the initial PCE for up to 200 h under 1 sun illumination, which is 10 times longer than that of the conventional ZnOX system (19 h).

ZnO/Graphene Oxide on Halloysite Nanotubes as a Superabsorbent Nanocomposite Photocatalyst for the Degradation of Organic Dyes

Using renewable photocatalysts for pollutant degradation represents a promising approach to addressing environmental water challenges by harnessing solar energy without additional energy consumption. However, for the practical use of photocatalysts, it is necessary to improve catalyst efficiency, considering cost and biocompatibility. In this study, we developed a new superabsorbent photocatalyst for the degradation of organic dyes in water. Our photocatalyst comprises halloysite nanotubes (HNTs) with a large outer diameter and Si-O and Al-O groups on the outer and inner surfaces, respectively; graphene oxide (GO) possessing numerous sp2 bonds and light-conductive properties; and ZnO, which can degrade organic molecules via a photon source. By exploiting the superabsorbent properties of GOs for organic dyes and stabilizing ZnO nanoparticles on HNTs to inhibit aggregation, our photocatalysts demonstrated significantly improved degradability compared to ZnO nanoparticles alone and combinations of ZnO with HNTs or GO. The structural characteristics of the nanocomposites were characterized using SEM, EDX, Raman spectroscopy, and XRD. Their enhanced photocatalytic activity was demonstrated by the degradation of rhodamine b in water, showing 95% photodegradation under UV illumination for 60 min, while the ZnO nanoparticles showed only 56% dye degradation under the same condition. Additionally, the degradation rate was enhanced by four times. Furthermore, the catalysts maintained their initial activity with no significant loss after four uses, showing their potential for practical implementation in the mass purification of wastewater.

Strainer-Separable TiO2 on Halloysite Nanocomposite-Embedded Alginate Capsules with Enhanced Photocatalytic Activity for Degradation of Organic Dyes

Photocatalysis driven by natural sunlight is an attractive approach to removing pollutants from wastewater. Although TiO₂–based photocatalysts using various support nano-materials with high catalytic activity and reusability have been developed for purifying wastewater, the centrifugal separation methods used for the nanocatalysts limit their use for treating large amounts of water. Here, we prepared a TiO₂ nano-catalyst supported on a halloysite nanotube (HNT)-encapsulated alginate capsule (TiO₂@HNT/Alcap) to recapture the catalysts rapidly without centrifugation. The structure of TiO₂@HNT/Alcap was characterized by X-ray diffraction, SEM, and TGA. In our system, the combination of HNTs and alginate capsules (Alcaps) improved the efficiency of adsorption of organic pollutants to TiO₂, and their milli = meter scale structure allowed ultra-fast filtering using a strainer. The TiO₂@HNT/Alcaps showed ~1.7 times higher adsorption of rhodamine B compared to empty alginate capsules and also showed ~10 and ~6 times higher degradation rate compared to the HNT/Alcaps and TiO₂/Alcaps, respectively.

Non-Thermal Plasma Treatment Coupled with a Photocatalyst for Antimicrobial Performance of Ihram Cotton Fabric

All Muslim pilgrims must wear Ihram clothes during the Hajj and Umrah seasons, which presents a great challenge regarding how to eliminate the spread of microbes attached to the cotton fabric of Ihram from the surrounding environment. Targeted fashion research of the recent past presents a new industrial treatment, which has led us to study the impact of heat directed from an atmospheric pressure plasma jet (APPJ), coupled with photocatalytic nanomaterials, for the antibacterial treatment of Escherichia coli (E. coli) attached to cotton fabric samples, to improve pollutant remediation. The average rates of heat transfer to the bacterial colonies attached to cotton fabric samples, as a function of the laminar mode, were 230 and 77 mW for dry and wet argon discharges, respectively. The jet temperatures (TJ) and heat transfer (QH) decreased more for wet argon discharge than for dry argon discharge. This is because, due to the wettability by TiO2 photocatalyst concentration dosage increases from 0 to 0.5 g L−1, a proportion of the energy from the APPJ photons is expended in overcoming the bandgap of TiO2 and is used in the creation of electron−hole pairs. In the Weibull deactivation function used for the investigation of the antibacterial treatment of E. coli microbes attached to cotton fabric samples, the deactivation kinetic rate of E. coli increased from 0.0065 to 0.0152 min−1 as the TiO2 precursor concentration increased. This means that the sterilization rate increased despite (TJ) and (QH) decreasing as the wettability by TiO2 photocatalyst increases. This may be due to photocatalytic disinfection and the generation of active substances, in addition to the effect of the incident plume of the non-thermal jet.

Application of Multiparametric Magnetic Resonance Imaging to Monitor the Early Antitumor Effect of CuS@GOD Nanoparticles in a 4 T1 Breast Cancer Xenograft Model

BACKGROUND

We have developed hybrid nanoparticles (NPs) by co-loading copper sulfide (CuS) NPs and glucose oxidase (GOD) (CuS@GOD NPs) to explore their antitumor properties.

PURPOSE

To investigate the feasibility of using multiparametric magnetic resonance imaging (MRI) including intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) and R₂ * mapping to quantitatively assess the early antitumor effect of CuS@GOD NPs.

STUDY TYPE

Prospective.

ANIMAL MODEL

The orthotopic BALB/c mice 4 T1 breast cancer model. The 4 T1 xenografts in group 1 mice received normal saline, group 2 received CuS@GOD NPs, group 3 received CuS NPs plus laser, and group 4 received CuS@GOD NPs plus laser (n = 28 for each group).

FIELD STRENGTH/SEQUENCE

A 3.0 T/IVIM-DWI MRI single-shot echo-planar imaging, R₂ * mapping spoiled gradient recalled echo (SPGR) sequence, T2-weighted images (T2WI) and T1-weighted images (T1WI) fast spin echo (FSE) sequence.

ASSESSMENT

The IVIM-DWI and R₂ * mapping were performed before and after treatment at 0 hour, 0.5 hour, 1 hour, 2 hours, 4 hours, and 24 hours in four groups and the MRI parameters were obtained. Correlation analysis between the MRI parameters and histological analyses was conducted.

STATISTICAL TESTS

One-way ANOVA, Pearson's correlation analysis, two independent samples t test, intraclass correlation coefficient. P < 0.05 was considered to be statistically significant.

RESULTS

In group 4, the tumoral D value was significantly higher than that of group 2 at 24 hours (0.541 ± 0.065 vs. 0.492 ± 0.051). The f value of group 4 was significantly lower than that of groups 1 and 2 at 2 hours (10.83 ± 2.16 vs. 14.28 ± 1.86, 16.67 ± 3.53, respectively). The R₂ * value was significantly increased at 0 hour in group 4 compared to that of groups 1 and 2 (64.552 ± 4.663 vs. 42.441 ± 1.516, 43.165 ± 1.709, respectively). D, f, and R₂ * were correlated with the histological staining results (r = 0.695-0.970).

DATA CONCLUSION

The IVIM-DWI-derived D and f and R₂ * mapping-derived R₂ * could monitor early response to CuS@GOD NPs treatment in vivo.

EVIDENCE LEVEL

2 TECHNICAL EFFICACY: Stage 2.

Photocatalytic activity and water purification performance of in situ and ex situ synthesized bacterial cellulose-CuO nanohybrids

The aim of this research was synthesizing of bacterial cellulose (BC) nanohybrids by incorporation of CuO-NPs and evaluation of their ability in the removing of microbial, heavy metals, and dyes pollutants from water. CuO-BC nanohybrids were synthesized by two in situ (sonochemical and precipitation) methods and compared with ex situ synthesized nanohybrid. FE-SEM images revealed that the growth of CuO-NPs in the sonochemically synthesized in situ substrate is better. The ex situ nanohybrid had the highest loading capacity (27.17 μg/cm² ) but the migration of CuO-NPs from this substrate was higher than in situ ones. According to antimicrobial tests, 80% and 90% of initial population of E. coli and S. aureus, respectively, were removed after 6 hr contact of substrates with water. The potential of the substrates in the adsorption of lead and arsenic was about 60% after 24 hr. About 75% of methylene blue and methyl orange dyes were adsorbed into substrates after 6 hr. CuO doped substrates had the photocatalytic activity and caused to decrease the oxygen content about 4%-7% during 6 hr. In general, the reusability of ex situ synthesized substrate was lower than in situ nanohybrids. Sonochemically synthesized substrate was suggested as the best nanohybrid for water purification applications in terms of morphological properties and reusability. PRACTITIONER POINTS: CuO-BC nanohybrids were prepared by in-situ and ex-situ methods. Well distribution of NPs and slower release was achieved by in-situ methods. Antimicrobial and photocatalytic activity of ex-situ nanohybrid was higher than in-situ ones. Dyes and heavy metals were removed successfully with nanohybrid substrates. Sonochemical in-situ nanohybrid exhibited the best water purification performance.