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The critical role of A, B-site cations and oxygen vacancies on the OER electrocatalytic performances of Bi0.15Sr0.85Co1−xFexO3−δ (0.2 ≤ x ≤ 1) perovskites in alkaline media

Jing Li,Fan Yang,Yunzhu Du,Min Jiang,Xiyang Cai,Qiaodan Hu,Junliang Zhang

Development of perovskite-type electrocatalysts with high activity, excellent durability and affordable cost provides a promising solution to promote commercialization of clean energy technologies. Here we prepared Bi 0.15 Sr 0.85 Co 1− x Fe x O 3−δ ( x  = 0.2, 0.4, 0.6, 0.8, 1) perovskites by the conventional solid-state reaction route, and investigated their OER electrocatalytic activity and durability in 0.1 M KOH solution to reveal the critical role of A, B-site cations and oxygen vacancies. Results show the OER activity decreases with increasing x . The optimum composition, BiSC 0.8 F 0.2 , presents impressive electrocatalytic performances with low overpotential (330 mV on rotation disk electrode, and 283 mV on carbon paper electrode at 10 mA/cm 2 ) and excellent long-time durability showing a small increase in the overpotential of 17 mV in 167.5 h. Comprehensive analysis and discussion on the bulk and surface properties reveal the critical role of A, B-site cations and oxygen vacancies on OER, and interrelations of Co 2+ fraction, oxygen non-stoichiometry and the OER overpotential have been established. Most importantly, a highly A-site deficient surface layer is found on the as-synthesized perovskite, which facilitate OER by exposing more active B-site cations. This work not only reports a promising OER electrocatalyst with high activity and superior durability, but also provides perspectives on relational design for highly efficient and stable perovskite electrocatalysts for OER using solid-state reaction method.

Exceptional Photocatalytic Activities of rGO Modified (B,N) Co-Doped WO3, Coupled with CdSe QDs for One Photon Z-Scheme System: A Joint Experimental and DFT Study

Fazal Raziq,Amil Aligayev,Huahai Shen,Sharafat Ali,Rahim Shah,Sajjad Ali,Syedul H. Bakhtiar,Asad Ali,Naghat Zarshad,Amir Zada,Xiang Xia,Xiaotao Zu,Muslim Khan,Xiaoqiang Wu,Qingquan Kong,Chunming Liu,Liang Qiao

Artificial Z-scheme, a tandem structure with two-step excitation process, has gained significant attention in energy production and environmental remediation. By effectively connecting and matching the band-gaps of two different photosystems, it is significant to utilize more photons for excellent photoactivity. Herein, a novel one-photon (same energy-two-photon) Z-scheme system is constructed between rGO modified boron-nitrogen co-doped-WO 3 , and coupled CdSe quantum dots-(QDs). The coctalyst-0.5%Rh x Cr 2 O 3 (0.5RCr) modified amount-optimized sample 6%CdSe/1%rGO3%BN-WO 3 revealed an unprecedented visible-light driven overall-water-splitting to produce ≈51 µmol h −1 g −1 H 2 and 25.5 µmol h −1 g −1 O 2 , and it remained unchanged for 5 runs in 30 h. This superior performance is ascribed to the one-photon Z-scheme, which simultaneously stimulates a two photocatalysts system, and enhanced charge separation as revealed by various spectroscopy techniques. The density-functional theory is further utilized to understand the origin of this performance enhancement. This work provides a feasible strategy for constructing an efficient one-photon Z-scheme for practical applications.

Deep Insight into the Mechanism of Catalytic Combustion of CO and CH4 over SrTi1–xBxO3 (B = Co, Fe, Mn, Ni, and Cu) Perovskite via Flame Spray Pyrolysis

Xing Yuan,Lingquan Meng,Chaohe Zheng,Haibo Zhao

Perovskites have been recognized as affordable substitutes for noble-metal catalysts for their tunable catalytic activity and thermal stability. Nevertheless, the highly demanding synthesis procedure still hinders the application of perovskites in catalytic combustion. In this work, a series of nanostructured SiTiO3 perovskites with B-site partial substitution by Co, Fe, Mn, Ni, and Cu are synthesized via flame spray pyrolysis in one step. The comprehensive characterizations on textural properties of nanostructured perovskites reveal that the flame-made perovskite nanoparticles all exhibit high crystal purity and large specific surface area (∼40 m2/g). Furthermore, the highest catalytic activity is achieved by SrTi0.5Co0.5O3 due to the formation of favorable oxygen vacancies, outstanding reducibility, and oxygen desorption capability. Additionally, the presence of 10 vol % water vapor during long-term testing indicates remarkable durability and water resistance. Finally, the CO oxidation and CH4 dehydrogenation on SrTiO3 incorporating Co atoms are more thermodynamically and kinetically favorable than those on other doped surfaces.

Effects of low intensity pulsed ultrasound on expression of B-cell lymphoma-2 and BCL2-Associated X in premature ovarian failure mice induced by 4-vinylcyclohexene diepoxide

Xu Haopeng,Xia Yi,Qin Juan,Xu Jie,Li Chongyan,Wang Yan

Background Premature ovarian failure (POF) is a common disease in the field of Gynecology. Low intensity pulsed ultrasound (LIPUS) can promote tissue repair and improve function. This study was performed to determine the effects of LIPUS on granulosa cells (GCs) apoptosis and protein expression of B-cell lymphoma-2 (Bcl-2) and BCL2-Associated X (Bax) in 4-vinylcyclohexene diepoxide (VCD)-induced POF mice and investigate the mechanisms of LIPUS on ovarian function and reserve capacity.Methods The current POF mice model was administrated with VCD (160 mg/kg) by intraperitoneal injection for 15 consecutive days. The mice were divided into the POF group, LIPUS group and control group. In the LIPUS group, the right ovary of mice was treated by LIPUS (acoustic intensity was 200 mW/cm2, frequency was 0.3 MHz, and duty cycle was 20%) for 20 min, 15 consecutive days from day 16. The mice of the POF group and control group were treated without ultrasonic output. The basic observation and body weight were recorded. Hematoxylin and eosin staining (H&E staining) and enzyme-linked immunosorbent assay (ELISA) were applied to detect ovarian follicle development, ovarian morphology and sex hormone secretion. Ovarian GCs apoptosis was detected by TUNEL assay and immunohistochemistry.Results The results showed that VCD can induce estrus cycle disorder, follicular atresia, sex hormone secretion decreased and GCs apoptosis in mice to establish POF model successfully. LIPUS significantly promoted follicular development, increased sex hormone secretion, inhibited excessive follicular atresia and GCs apoptosis. The mechanism might be achieved by increasing the protein expression of Bcl-2 and decreasing the expression of Bax in ovaries.Conclusion sLIPUS can improve the POF induced by VCD. These findings have the potential to provide novel methodological foundation for the future research, which help treat POF patients in the clinic.

Highly dispersed and stable Fe species supported on active carbon for enhanced degradation of rhodamine B through peroxymonosulfate activation: Mechanism analysis, response surface modeling and kinetic study

Yan Wu,Ling-Hui Kong,Rong-Fang Shen,Xiao-Jing Guo,Wen-Ting Ge,Wen-Jie Zhang,Zhen-Yue Dong,Xi Yan,Yan Chen,Wan-Zhong Lang

Herein, highly dispersed Fe species supported on activated carbon (CA-Fe-C) was fabricated with the aid of citric acid , showing excellent catalytic performance and stability for the degradation of rhodamine B (RhB) through peroxymonosulfate (PMS) activation. The radical quenching study, electron paramagnetic resonance (EPR) measurement and PMS consumption analysis confirmed the RhB degradation mechanism involving reactive radical species attacking RhB and non-radical oxidation pathway. The main degradation intermediates were identified by LC-MS, and the possible RhB degradation pathways were deduced. A multivariate quadratic polynomial model was developed using the response surface methodology (RSM) to examine how the removal of RhB was influenced by several quantifiable factors, with the objective of optimizing RhB removal. The analysis of variance (ANOVA) was used to evaluate the adequacy and significance of the proposed model. The effects of solution pH values, initial concentration, inorganic anions, PMS dosage, catalyst dosage, and metal loading amount on RhB removal were investigated. The method of initial rates was employed to determine the intrinsic reaction rate law, and the reaction was identified to follow the Langmuir-Hinshelwood (L-H) kinetics model.

Supramolecular Nanosheets Assembled from Poly(ethylene glycol)-b-poly(N-(2-phenylethyl)glycine) Diblock Copolymer Containing Crystallizable Hydrophobic Polypeptoid: Crystallization Driven Assembly Transition from Filaments to Nanosheets

Yuhan Wei,Jiliang Tian,Zekun Zhang,Chenhui Zhu,Jing Sun,Zhibo Li

Supramolecular two-dimensional (2D) nanomaterials from block copolymers have received great interest for their unique structure and properties. Here, we report the formation of ultrathin nanosheets from self-assembly of amphiphilic poly(ethylene glycol)-b-poly(N-(2-phenylethyl)glycine) (PEG-b-PNPE) diblock copolymers, which contain rigid crystallizable polypeptoid segment. The PEG-b-PNPE copolymers were synthesized via ring opening polymerization (ROP). The obtained PEG-b-PNPE diblock copolymers can spontaneously form highly ordered structures in PEG selective solvents such as water and methanol. The copolymers with short PNPE segment can directly form nanosheets in water, and the obtained 2D nanosheets have a uniform thickness of 4–5 nm. In contrast, the copolymers with relatively long PNPE segment can only assemble into nanosheets with the assistance of methanol. It is proposed that the crystallization and π–π stacking of PNPE blocks play critical roles in the formation of the nanosheet as suggested by grazing incidence wide-angle X-ray scattering (GIWAXS). During the process of adding water into copolymer methanol solution, the nanosheets were observed to evolve from individual nanofibers, to parallel aligning nanofibers, and eventually to the nanosheet structures verified by transmission electron microscopy (TEM) and cryo-TEM characterizations. We demonstrated that the preassembled filament behave as a fundamental packing motif to align laterally and further fuse into platelet-like structures. The assembly structure evolution process was tracked by TEM, atomic force microscopy, and cryo-TEM techniques. The understandings of supramolecular 2D nanosheet formation offer a new opportunity to make hierarchical nanostructures from polypeptoids containing copolymers.

A high-performance light-driven photoelectrochemical sensor based on CdIn2S4/b-TiO2/GO type-II 2D/3D heterojunction for the detection of baicalein in natural plant samples

Xiaoqian Sun,Rongjie Li,Yilin Wang,Kaijia Liu,Yuhui Qiu,Kunxiang Deng,Yixi Xie,Pengcheng Zhao,Junjie Fei

The remarkable pharmacological activities of flavonoids and their effects on human health have prompted many studies. To solve the problem that flavonoids are difficult to be accurately quantified, a novel photoelectrochemical (PEC) sensor based on CdIn 2 S 4 /b-TiO 2 /GO was created to detect the baicalein (BCA). By using physical ultrasonic compounding, a straightforward and effective CdIn 2 S 4 /b-TiO 2 /GO composite was created. The composite’s photoelectric effect was 14 times greater than that of the individual material. When BCA was present, a flavonoid-TiO 2 nanoconjugate was formed based on the interaction between b-TiO 2 and BCA. This interaction prevented the formation and decreased charge transfer of photoporous holes, resulting in a significant decline in photocurrent. Therefore, the PEC sensor based on the change of the electrode surface state can realize the sensitive detection of BCA. The PEC sensor has a wide linear detection range of 1 nM − 30 μM with a limit of detection of 0.5 nM. In addition, the sensor has exhibited excellent accuracy in detecting BCA in the roots and leaves of Scutellaria baicalensis, which can be used for the detection of actual samples.

Turn-on fluorogenic and chromogenic detection of Fe3+ and Cr3+ in a completely water medium with polyacrylamide covalently bonding to rhodamine B using diethylenetriamine as a linker

TongMou Geng,RongYi Huang,DaYu Wu

A new monomeric fluorophore N-acryl-N′′-(rhodamine B-yl) diethylenetriamine (ARBD) was synthesized. Free radical precipitation copolymerization was carried out in order to prepare a water-soluble fluorescent copolymer (poly(AM–ARBD)), based on acrylamide. The chemical constitution of poly(AM–ARBD) was studied by FTIR and 1H NMR spectroscopy. The fluorescent characteristic of the aqueous solutions of the copolymer was investigated both in varied pH and in the presence of metal cations. It was found that polymeric sensors exhibited high selectivity and sensitivity in colorimetric and fluorescence responses toward Fe3+ and Cr3+ over other metal ions. The polymeric sensors were non-fluorescent in the spirolactam form and could be selectively converted into the fluorescent ring-opened amide form in the presence of Fe3+ or Cr3+ ions that lead to fluorescence enhancements and colorimetric changes from colorless to red or pink, respectively. Fe3+ and Cr3+ can be sensed with a detection limit at 1.34 × 10−4 and 9.90 × 10−6 mol L−1, respectively. The combination of water solubility and positive fluorescence response as well as color change is therefore particularly promising for the practical utility of this sensor.

Leveraging Concentration Imbalance-Driven DNA Circuit as an Operational Amplifier to Enhance the Sensitivity of Hepatitis B Virus DNA Detection with Hybridization-Responsive DNA-Templated Silver Nanoclusters

Suo Lv,Qunyan Yao,Jiasheng Yi,Jingyi Si,Yifan Gao,Shao Su,Changfeng Zhu

Hepatitis B virus (HBV) infection remains a major global health concern, necessitating the development of sensitive and reliable diagnostic methods. In this study, we propose a novel approach to enhance the sensitivity of HBV DNA detection by leveraging a concentration imbalance-driven DNA circuit (CIDDC) as an operational amplifier, coupled with a hybridization-responsive DNA-templated silver nanocluster (DNA-AgNCs) nanoprobe named Q·C6-AgNCs. The CIDDC system effectively converts and amplifies the input HBV DNA into an enriched generic single-stranded DNA output, which subsequently triggers the fluorescence of the DNA-AgNCs reporter upon hybridization, generating a measurable signal for detection. By incorporating the DNA circuit, we not only achieved enhanced sensitivity with a lower detection limit of 0.11 nM but also demonstrated high specificity with single-base mismatch discriminability for HBV DNA detection. Additionally, this mix-and-detect assay format is simple, user-friendly, and isothermal. This innovative strategy holds promise for advancing molecular diagnostics and facilitating the effective management of HBV-related diseases.

Reply to Hosseini Monjezi, B.; Lützenkirchen, J. Comment on “Zhou et al. Adsorption Behaviors of Lanthanum (III) and Yttrium (III) Ions on Gibbsite. Minerals 2023, 13, 1530”

Zongke Zhou,Quan Wan,Wenbin Yu,Xin Nie,Shuguang Yang,Shuqin Yang,Zonghua Qin

Development and Evaluation of Cucurbitacin B Microemulsion: the Effect of Oil Phase and Aqueous Phase on Drug Percutaneous Absorption Based on ATR-FTIR Spectroscopy and Molecular Modeling

Tian Qi,Guo Jianbo,Zhang Qi,Fang Liang,Liu Chao,Xu Hui

The present study aimed to develop a cucurbitacin B microemulsion (CuB-ME) and investigate the mechanism of the enhanced drug skin absorption at the molecular level. Firstly, the pseudo-ternary phase diagrams were developed to evaluate the effect of composition on microemulsion properties systematically. The formulation composition types and ratios of oil phase, surfactant, co-surfactant, and aqueous phase were optimized by an in vitro skin permeation experiment, and the optimized formula was confirmed with the pharmacodynamics study. Furthermore, the molecular mechanism of enhanced skin permeation was investigated using ATR-FTIR and molecular modeling. As a result, the optimized CuB-ME formulation was composed of Azone:Tween 80:ethanol:water = 2.5:16.9:5.6:75.0 ( w / w / w / w ). The oil phase improved skin permeation by disordering the stratum corneum intercellular liquid, while the aqueous phase impacted the particle size of the microemulsion and permeability coefficient of the drug. Besides, the hydration state of skin lipid also enhanced drug permeation by the interaction of water and the polar head of ceramide. The in vitro skin permeation amount was 45.47 ± 10.39 μg/cm 2 , and no significant skin irritation was observed. The pharmacodynamics study demonstrated that CuB-ME had a significant therapeutic effect on the animal tumor model. In conclusion, the CuB-ME was developed successfully and the effect of the oil phase and aqueous phase on drug skin permeation was clarified at the molecular level.

In-situ formation of ultrafine MgNi3B2 and TiB2 nanoparticles: Heterogeneous nucleating and grain coarsening retardant agents for magnesium borate in Li–Mg–B–H reactive hydride composite

Xu Huang,Xuezhang Xiao,Xuancheng Wang,Zhendong Yao,Jiahuan He,Xiulin Fan,Lixin Chen

Li–Mg–B–H reactive hydride composite (RHC) has attracted extensive attention over the past decades for its extremely high hydrogen storage capacity (11.5 wt%). But the sluggish desorption kinetics for the second step dehydrogenation reaction need to be further improved. Herein, short rod-like TMTiO 3 (TM = Co, Ni) bimetallic oxides , which contain two kinds of transition metal elements, were synthesized and introduced into Li–Mg–B–H RHC for the first time. The NiTiO 3 exhibits excellent catalytic effect on the hydrogen desorption kinetic performance of Li–Mg–B–H RHC, and the incubation period for the second step dehydrogenation reaction is eliminated completely by reducing the apparent activation energy for the generation of MgB 2 from 296 kJ/mol to 269 kJ/mol. The NiTiO 3 doped Li–Mg–B–H RHC can desorb about 9.0 wt% H 2 without obvious attenuation of kinetic performance in five cycles. Mechanism analyses reveal that the in-situ generated nano-sized MgNi 3 B 2 and TiB 2 species (∼5 nm) both meet the critical value ( < 10%) of the edge-to-edge matching model (5.77% for MgNi 3 B 2 and 2.22% for TiB 2 ), which play a significant role in supporting the nucleation of MgB 2 . Meanwhile, the extremely fine MgNi 3 B 2 and TiB 2 heterogeneous nucleation sites can inhibit the excessive growth for a single crystal nucleus of MgB 2 . The heterogeneous nucleation and grain refinement mechanisms caused by the novel bimetallic oxide could provide alternative insights into designing an in-situ generated nano-sized catalytic hydrogen storage system with enhanced kinetics and cyclic stability for hydrogen-fueled applications.