Direct Preparation Research Articles

Prevalence of Intestinal Parasitic Infections and Associated Factors among Presumptive Pulmonary Tuberculosis Patients at Debre Tabor Referral Hospital, South Gondar, Northwest Ethiopia: A Cross-Sectional Study.

In developing countries, intestinal parasitic infections (IPIs) and tuberculosis (TB) coinfections have been perceived to be high. The geographic distributions of helminths and TB overlap substantially. Parasitic infections affect the outcome of TB by changing the cell-mediated immune response to a humoral response, while Mycobacterium infection favors the immune escape of helminths. There are limited studies on the epidemiology of intestinal parasites among presumptive pulmonary TB (PTB) patients in Ethiopia. Therefore, this study is aimed at determining the prevalence of intestinal parasitic infections and associated factors among patients with presumptive pulmonary tuberculosis at Debre Tabor Referral Hospital. A hospital-based cross-sectional study was conducted from March to June 2021. The sociodemographic data and associated factors were collected using a structured questionnaire, and stool samples were collected by convenient sampling technique and processed for the detection of intestinal parasites using a direct wet mount saline preparation and formal ether concentration technique. The data was coded, cleaned, and analyzed by SPSS version 23. Bivariate and multivariable analyses were conducted to determine an adjusted odds ratio (AOR). p value < 0.05 was considered statistically significant. The overall prevalence of intestinal parasitosis was 25.6% (81/316); of these, 12.9% (41/316) were protozoan infections and 12.7% (40/316) were helminth infections. Multivariable logistic regression analysis showed that being older than 36 years (AOR: 4.35; 95% CI: 1.26, 13.91; p = 0.001), rural residence (AOR: 3.46; 95% CI: 1.18, 9.97; p < 0.001), unable to read and write (AOR = 2.62; 95%CI = 2.15, 8.43; p = 0.004), and use of river water (AOR: 3.47; 95% CI: 1.62, 8.21; p < 0.001) were associated with intestinal parasitic infections. The present study showed that the prevalence of intestinal parasitosis among presumptive pulmonary tuberculosis patients was high in the study area. Age, residence, educational status, and source of water were significant factors in IPIs among presumptive TB patients. Moreover, our findings suggest a proper health education program for good personal hygiene habits, the coloration of water, avoiding open-field defecation, and also preventative measures to avoid the acquisition of IPIs in patients with TB. Presumptive tuberculosis patients should be screened and treated accordingly. Additionally, it needs further research and recommends more assessment for intestinal parasitic infection in PTB patients.

Fabrication of Multiple-Channel Electrochemical Microneedle Electrode Array via Separated Functionalization and Assembly Method.

Real-time monitoring of physiological indicators inside the body is pivotal for contemporary diagnostics and treatments. Implantable electrodes can not only track specific biomarkers but also facilitate therapeutic interventions. By modifying biometric components, implantable electrodes enable in situ metabolite detection in living tissues, notably beneficial in invasive glucose monitoring, which effectively alleviates the self-blood-glucose-managing burden for patients. However, the development of implantable electrochemical electrodes, especially multi-channel sensing devices, still faces challenges: (1) The complexity of direct preparation hinders functionalized or multi-parameter sensing on a small scale. (2) The fine structure of individual electrodes results in low spatial resolution for sensor functionalization. (3) There is limited conductivity due to simple device structures and weakly conductive electrode materials (such as silicon or polymers). To address these challenges, we developed multiple-channel electrochemical microneedle electrode arrays (MCEMEAs) via a separated functionalization and assembly process. Two-dimensional microneedle (2dMN)-based and one-dimensional microneedle (1dMN)-based electrodes were prepared by laser patterning, which were then modified as sensing electrodes by electrochemical deposition and glucose oxidase decoration to achieve separated functionalization and reduce mutual interference. The electrodes were then assembled into 2dMN- and 1dMN-based multi-channel electrochemical arrays (MCEAs), respectively, to avoid damaging functionalized coatings. In vitro and in vivo results demonstrated that the as-prepared MCEAs exhibit excellent transdermal capability, detection sensitivity, selectivity, and reproducibility, which was capable of real-time, in situ glucose concentration monitoring.

Heavily Doped Carbon Nitride Nanocrystal Promotes Visible-Near-Infrared Photosynthesis of Hydrogen Peroxide with Near-Unit Photon Utilization.

Direct photosynthesis of hydrogen peroxide (H2O2) from water and oxygen represents an intriguing alternative to the current indirect process involving the reduction and oxidation of quinones. However, limited light utilization and sluggish charge transfer largely impede overall photocatalytic efficiency. Herein, we present a heavily doped carbon nitride (CNKLi) nanocrystal for efficient and selective photoproduction of H2O2 via a two-electron oxygen reduction reaction (ORR) pathway. CNKLi induces metal-to-ligand charge transfer (MLCT) and electron trapping, which broadens the light absorption to the visible-near-infrared (vis-NIR) spectrum and prolongs the photoelectron lifetime to the microsecond time scale with an exceptional charge diffusion length of ∼1200 nm. Near-unit photoutilization with an apparent quantum yield (AQY) of 100% for H2O2 generation is achieved below 420 nm. Impressively, CNKLi exhibits an appreciable AQY of 16% at 700 nm, which reaches the absorption capacity (∼16%), thus suggesting a near-unit photon utilization <700 nm. In situ characterization and theoretical calculations reveal the facilitated charge transfer from K+ to the heptazine ring skeleton. These findings provide an approach to improve the photosynthetic efficiency of direct H2O2 preparation in the vis-NIR region and expand applications for driving kinetically slow and technologically desirable oxidations or high-value chemical generation.

Recovery of valuable metals from manganese purification sludge (SPS) containing Mn-Ni-Co sulfide and preparation of battery-grade Ni-Co-Mn sulfate solution

The manganese production industry produces a large amount of sulfide purification sludge (SPS) every year, representing a hazardous solid waste but also a valuable secondary resource for Ni, Co, and Mn. In this paper, the recovery of Ni, Co, and Mn from the SPS was achieved by (i) leaching with a solution of hydrogen peroxide, (ii) selectively extracting nickel, cobalt and manganese, (iii) solvent extraction for zinc removal, and finally obtained the battery-grade Ni-Co-Mn sulfate solution. During the hydrogen peroxide solution leaching stage, the leaching efficiency of Co, Mn, and Ni reached 98.5%, 98.6%, and 95.6%, respectively. A synergistic extraction system (SES) consisting of decyl 4-picolinate and dinonylnaphthalene sulfonic acid was used to selectively extract Ni, Co, and part of Mn, and the extraction of Ni and Co was >99.8% and 95.5%, respectively. The loaded organic was subjected to four-stage countercurrent scrubbing using a 5 g/L H2SO4 solution, resulting in nearly 100% removal of Ca and Mg. After that, 150 g/L H2SO4 was used to strip Ni, Co, and Mn from the loaded organic to obtain a crude Ni-Co-Mn sulfate solution. Finally, D2EHPA was utilized for the extraction of impurity Zn from the stripping solution to obtain a battery-grade Ni-Co-Mn sulfate solution with <5 × 10−4 g/L of Zn. Compared to traditional technology, the novel process not only enables the recovery of valuable Ni, Co, and Mn in SPS but also facilitates their direct preparation into battery-grade nickel‑cobalt‑manganese sulfate solution, which has the advantages of a short process and high added value.

Optimized carbon extraction replicas for transmission electron microscopy of nanoprecipitates in microalloyed low-carbon steels

Nanoprecipitates play a decisive role in strengthening of microalloyed low-carbon steels. The direct carbon extraction replica (CER) method is a promising way to extract the nanoprecipitates from the surrounding iron matrix for a detailed characterization of their structure and chemistry using electron microscopy. Better results can generally be obtained by electron microscopy when the magnetic matrix is removed. However, there are challenges in the preparation of relatively thin CERs, especially during stripping and cleaning stages of the procedure. In this contribution, a systematic study of different parameters associated with the direct CER preparation method was performed on a vanadium-microalloyed low-carbon model steel to improve the replication procedure. Relatively low nanoscale surface kurtosis of the iron matrix with respect to the thickness of the deposited carbon layer was found to be important for successful replications from different crystallographic planes of the matrix during the stripping stage. Furthermore, modified water-based stripping and cleaning solutions were introduced that minimized wrinkling, coalescence, and disintegration of ∼8 nm thick CERs. These results are supported by (scanning) transmission electron microscopy observations, which showed successful extraction of V-rich nanoprecipitates in a size range of 1–50 nm from both the ferritic and bainitic microstructures. The modified method improves the common direct CER preparation procedure and can be used to study precipitates in a wide range of microalloyed low-carbon steels.

Enhancement of piezoelectric properties of CaBi2Nb2O9 ceramics by Ce doping and direct reaction sintering

CaBi2Nb2O9 (CBN) with the Aurivillius phase has a high Curie temperature (TC) and remarkable fatigue resistance, which has great potential for application as high-temperature sensors. However, due to its low piezoelectric properties, its practical application remains a great challenge. In this paper, Ca1-xCexBi2Nb2O9 ceramics were prepared by the direct reaction sintering (DRS) and conventional preparation (CP) methods, respectively. The experimental results indicate that Ce doping can increase the piezoelectric coefficient d33 of CBN ceramics by about two times. Among them, the grain size of the samples prepared by the DRS method is finer and more uniform, and the d33 value of DRS samples is about 3.6–9.4 % higher than that of CP samples. The DRS sample Ca0·97Ce0·03Bi2Nb2O9 has a d33 value of 18.9 pC/N, a TC of 948 °C, and a resistivity of 1.1 × 105 Ω cm at 600 °C. This study shows that DRS method is an effective densification method, which can prepare CBN-based ceramics with excellent comprehensive properties, and provides an innovative preparation route to explore CBN-based ceramics with excellent piezoelectric properties.

Unlocking the Power of Acyl Fluorides: A Comprehensive Guide to Synthesis and Properties

AbstractAcyl fluorides have emerged as versatile reagents in various synthetic endeavors, offering a range of advantages over their counterparts, acyl chlorides. This study delves into the properties and reactivity of acyl fluorides, particularly their reaction with amines and alcohols, to elucidate their distinct characteristics. We also introduce a facile and practical synthesis of acyl fluorides from a stable solution of CF3O− salt. Additionally, we establish an efficient one‐pot process for the direct preparation of amides or esters from corresponding acids and amines or alcohols, showcasing the remarkable efficiency of acyl fluorides in these transformations.

An Experimental Study on Direct Hydroxylation of Toluene in a Dielectric Barrier Discharge System Under Ambient Conditions

ABSTRACT Non-thermal plasma is a promising alternative to be utilized for the synthesis of hydroxytoluenes through one-pot hydroxylation of toluene. Direct preparation of hydroxytoluenes from vaporized toluene was conducted in air at room temperature and atmospheric pressure using a dielectric-barrier discharge (DBD) reactor. The preliminary results obtained from this study showed that cresols were formed along with benzaldehyde, benzyl alcohol, and phenol. O atoms generated by air plasma in collision with toluene produced OH and benzyl radicals, which led to further reactions. The mechanism of the reaction of reactive oxygen species (ROS) with toluene and toluene-derived radicals to yield the observed oxidation products was discussed.

Spontaneous Line Defect‐Induced Co4Te7 Superlattices on SrTiO3(001) Featuring Flat Bands

Abstract1D structures/patterns (e.g., line defect arrays, 1D Moiré patterns) embedded in 2D materials provide fascinating platforms for exploring versatile intriguing phenomena, for example, 1D Luttinger liquids and charge density waves (CDWs). Despite persistent efforts, incorporating periodic 1D patterns into 2D materials remains an ongoing pursuit. Herein, the direct preparation of monolayer 1D‐defect‐induced Co4Te7 superlattices (with periodic Te defect lines in the upper Te layer in 1T‐CoTe2) is reported, on lattice‐matched SrTiO3(001) (STO(001)) substrates via molecular beam epitaxy (MBE). Utilizing on‐site scanning tunneling microscopy/spectroscopy (STM/STS) combined with density functional theory (DFT) calculations, the detailed atomic structure of monolayer Co4Te7 is identified, and its formation mechanisms from the synergistic effects of the Co/Te precursor ratio and adlayer‐substrate interfacial coupling are uncovered. The potential flat‐band feature of the monolayer Co4Te7 is also unveiled. This work should hereby offer valuable insights into the engineering of periodic 1D‐defect patterns in 2D materials, as well as the atomic‐scale structure and electronic property characterizations, thus paving ways for their intriguing property investigations.

Parasitological, Bacterial and Fungal Evaluation of Some Ready-to-Eat Foods Sold by Vendors in Port Harcourt, Rivers State

Aims: To determine the prevalence and distribution of gastrointestinal parasites, bacteria and fungi in Date, Wet Tiger nut, Dry Tiger nut, Kuli-kuli and kola nuts sold by roadside vendors in nine locations in Rivers State. Study Design: A total of 270 samples were procured randomly from roadside sellers. Place and Duration of Study: Department of Animal and Environmental Biology [parasitology unit), University of Port Harcourt, between March and July 2022. Methodology: The 270 samples were examined for gastrointestinal parasites using direct wet preparation and sedimentation techniques, while 135 of the samples selected based on type and location were examined for bacteria and fungi using standard microbial techniques. Results: Out of the 270 samples examined, 124(49.9%) were positive for gastrointestinal parasites as follows; Ascaris lumbricoides 52(19.3%), Ancylostoma spp 39(14.4%), Trichuris trichiura 19(7.0%) and Giardia lamblia 14(5.2%). dry Tiger nut recorded the highest prevalence 39(72.2%) and Kola nut 11(20.4%) had the least prevalence. Aluu had the highest prevalence 21(70.0%) while Rumuokoro recorded the least 3(10.0%) p=05. Of the 135 samples, 96(71.1%) was positive for bacteria while 19(14.1%) was positive for Candida species (fungi). The bacteria isolated were Escherichia coli 48(35.5%), Klebsiella species 32(23.7%) and Staphylococcus aureus 16(11.9%). Kola nut recorded the highest bacterial contamination 26(96.3%) and Date the lowest 10 (37.0). Samples from Choba had the highest bacterial contamination 12(80%) while Alakahia had the least bacterial contamination 7(46.7%) p=05. Dry Tiger nut 12(44.4%) and Wet Tiger nut 7(25.9%) were the only sample types with fungal contamination. Conclusion: Vendors and consumers should be educated on the possible health implications of poorly handled RTE foods, and government should implement and enforce sanitary rules to preserve the environmental quality of areas where RTE foods are being processed and sold.

Oxidation transformation and vacuum separation for direct preparation of antimony trioxide products from lead anode slime

Antimony, a crucial metal resource, plays a significant role in various important fields. This study developed an environmentally and efficient technology for the preparation of antimony oxide, which consists of oxidative transformation and vacuum separation of lead anode slime (LAS). The chemical environment in which each substance is subjected to changes, causing the substances containing Sb and As to both be oxidatively transformed into Sb2O3 and As2O3 in the oxidation section. In a further vacuum ambiance, As2O3 and Sb2O3 are volatilized into the gas phase, respectively. analysis results confirm that the antimony trioxide product isolated and prepared was a high-quality nanoscale cubic crystalline Sb2O3 powder. The novel method effectively combines the oxidation and volatilization properties of each Sb-containing and As-containing materials, enabling the efficient recovery of valuable Sb metal resource from LAS while ensuring safe and sustainable avoidance of arsenic contamination. Most importantly, the whole process generates no waste that could harm the environment. Overall, these findings provide a convenient and eco-friendly approach for extracting valuable metals from secondary resources containing antimony.

Green imine synthesis from amines using transition metal and micellar catalysis.

Imines are a versatile class of chemicals with applications in pharmaceuticals and as synthetic intermediates. While imines are conventionally synthesized via aldehyde-amine condensation, their direct preparation from amines can avoid the need for the independent preparation of the aldehyde coupling partner and associated constraints with regard to aldehyde storage and purification. The direct preparation of imines from amines typically utilizes transition metal catalysis and is often well-aligned with green chemistry principles. This review provides a comprehensive overview of transition metal catalysed imine synthesis, with a particular focus on the copper-catalyzed oxidative coupling of amines. The emerging application of micellar catalysis for imine synthesis is also surveyed due to its potential to avoid the use of hazardous solvents and intensify these reactions through reduced catalyst loadings and locally increased reactant concentrations. Future directions relating to the confluence of these two areas are proposed towards the more sustainable preparation of imines.

Targeted multi-analyte UHPLC-MS/MS methodology for emerging contaminants in septic tank wastewater, sludge and receiving surface water.

Septic tanks treat wastewater of individual houses and small communities (up to 2000 people in Scotland) in rural and semi-urban areas and are understudied sources of surface water contamination. A multi-analyte methodology with solid phase extraction (SPE), ultra-sonic extraction, and direct injection sample preparation methods was developed to analyse a comprehensive range of emerging contaminants (ECs) including prescription and over-the-counter pharmaceuticals and related metabolites, natural and synthetic hormones, and other human wastewater marker compounds in septic tank influent and effluent, river water, suspended solids, and septic tank sludge by ultra-high-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). The number of quantifiable compounds in each matrix varied from 68 in septic tank wastewater to 59 in sludge illustrating its applicability across a range of matrices. Method quantification limits were 2.9 × 10-5-1.2 μg L-1 in septic tank influent, effluent and river water, with ≤0.01 μg L-1 achieved for 60% of ECs in all three water matrices, and 0.080-49 μg kg-1 in sludge. The developed method was applied to a septic tank (292 population equivalents) and the receiving river in the North-East of Scotland. Across all samples analysed, 43 of 68 ECs were detected in at least one matrix, demonstrating the method's sensitivity. The effluent concentrations suggest limited removal of ECs in septic tanks and a potential impact to river water quality for some ECs. However, further monitoring is required to better appreciate this. The developed methodology for a wide variety of ECs in a range of liquid and solid phases will allow, for the first time, a comprehensive assessment of ECs fate and removal in septic tanks, and their impact to surface water quality.

Pd/NHC catalyzed reduction and coupling of nitroaromatics for the synthesis of diarylamines.

Herein, we report a one-pot approach to diarylamines through the reductive homocoupling of nitroaromatics, employing triethylsilane as the reducing agent and Pd/NHC as the catalyst. This method enables nitroaromatics to serve both as electrophilic reagents and as precursors of nucleophilic reagents, allowing for the direct preparation of diarylamines without the need to isolate aromatic primary amines.

Karyotype analysis of Quasipaaspinosa David, 1875 (Anura, Dicroglossidae) with conventional cytogenetic techniques.

The current study analyzed the chromosomal karyotype of Quasipaaspinosa David, 1875 from Hunan Province, China. The karyotype, C-banding, BrdU-banding pattern were characterized using direct preparation of bone-marrow cells and hemocyte cultures. The findings indicated that Q.spinosa was a diploid species (2n = 26) that lacked heteromorphic chromosomes and secondary constrictions. C-banding analysis revealed an abundance of positive signals in the centromere regions, while the BrdU-banding pattern showed three phases in both male and female, occurring consistently and in chronological sequence during S-phase. Notably, there was no asynchronous replication in the late phase. This study enhanced our understanding of the karyotypic structure of Q.spinosa by conventional cytogenetic techniques, thus providing essential scientific insights into the cytogenetics of Q.spinosa.

Preparation of Bose-Einstein condensate of dysprosium atoms based on demagnetization cooling

In magnetic atomic gases, the dipolar relaxation process couples the system spin and kinetic degrees of freedom. When the average kinetic energy is significantly lower than the Zeeman splitting, the atoms predominantly occupy the lowest Zeeman state. As the Zeeman splitting approaches the average kinetic energy, some atoms transfer to adjacent Zeeman states through dipolar relaxation, converting kinetic energy into Zeeman energy. By utilizing optical pumping, atoms transferred to higher spin states can be repumped to the ground state, thereby achieving a continuous cooling cycle and effectively lowering the system’s temperature. As the energy removed in a single cooling cycle is much larger than the energy of scattered photons, this demagnetization cooling scheme significantly enhances cooling effciency and reduces atomic loss. In this work, we establish state-coupled equations that incorporate dipolar relaxation and optical pumping to analyze the demagnetization cooling process, modeling the evolution of atom number and temperature during the cooling of &lt;inline-formula&gt;&lt;tex-math id="M1"&gt;\begin{document}$^{164}{\text{Dy}}$\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt; atoms. We develop a strategy to generate an optimal magnetic field waveform by maximizing the demagnetization rate. Based on this strategy, we investigate the influence of crucial experimental parameters on demagnetization cooling and determine their specific ranges for producing large atom number of BEC, including the optical dipole trap frequency, as well as the intensity and polarization purity of the optical pumping light. The results indicate that demagnetization cooling enables the direct preparation of a large number of dysprosium BEC with sub-second timescales, reducing the cooling time by an order of magnitude compared to conventional methods for dysprosium atoms. Furthermore, it could achieve a cooling effciency of &lt;inline-formula&gt;&lt;tex-math id="M2"&gt;\begin{document}$\chi \approx 44.92$\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt;, an order of magnitude higher than that of traditional evaporative cooling.

Implementasi Persiapan Perkawinan di Paroki Bunda Hati Kudus Woloan

The preparation of marriage should be carried out in a gradual and continuous process, which must be given by the Shepherd of souls in the form of sermons and catechesis adapted from childhood, youth, and adulthood. However, according to initial observations made, researchers saw that in the Parish of Our Lady of the Sacred Heart of Woloan, marriage preparations are only given to people who have reported holding a wedding celebration. This encourages researchers to know and describe people's understanding of marriage preparation, describe the implementation of marriage preparation in the Parish of Mother of the Sacred Heart of Woloan, and describe efforts to improve the effectiveness of marriage preparation in the Parish of Mother of the Sacred Heart of Woloan. This research uses a type of descriptive research with a qualitative approach. The research techniques used for this study were observation, interviews, and documentation. The data sources are the marriage preparation team, prospective married couples, and married couples in the Parish of Our Lady of the Sacred Heart of Woloan. From the results of the research obtained, theresearchers concluded that marriage preparation is an initial process that must be taken by prospective married couples to get to know each other's duties and responsibilities as husband and wife, and understand what agreement they will build. In addition, in its application of the 3 forms of marriage preparation listed in the Apostolic Advice Familiaris Consortio number 66, namely far preparation, and close preparation, only 1 is applied in Woloan Parish, namely direct marriage preparation (preparatio directa). Therefore, in order to improve the effectiveness of marriage preparation, things such as improving the quality of the marriage preparation team, socialization about distant preparation, trying to procure close preparation courses, and always holding evaluation meetings for the marriage preparation team need to be done.

Enhancing mechanical performance of green fiber cement composites: Role of eco-friendly alkyl ketene dimer on surfaces of hemp fibers

Fiber composites reinforced natural fibers have attracted more attention in sustainable building materials due to the high Young's modulus, availability, and biodegradability. However, poor interfacial bonding of the fiber-reinforced cement composites attributed to the intrinsically swelling-shrinkage behavior of the hydrophilic natural fibers, seriously limits the strength development of the composite. Here, an eco-friendly and low-cost surface treatment agent, alkyl ketene dimer (AKD), is innovatively introduced for reinforcing the combined effect of hemp fiber (HF)/cement matrix. The experimental approach includes the chemical modification of hemp fibers, followed by the direct preparation of fiber cement composites. Fourier transformation infrared spectroscopy (FTIR) and water absorption test analyses confirmed that the modified HF surface was successfully grafted with AKD, leading to superior hydrophobic characterization and reduced swelling-shrinking behavior. Adding the modified HF to the cement composites effectively enhanced their mechanical properties and toughness capacity by strengthening the interfacial bond of modified HF/Mortar. The modified fiber-reinforced mortar has the highest increment (28 % in compressive strength and 24 % in flexural strength, respectively) from 7 d to 28 d among all investigated mortars. Furthermore, the micro-observation of fractured mortar composites supports the strengthened interface of the modified fibers/cement matrix. The study provides a feasible and practical approach to improving the comprehensive strength properties of hemp fiber-reinforced cement composites. It benefits the practical industrial-scale application of biomaterials in low-cost housing, thus enhancing sustainability.

Porphyrin-Based Two-Dimensional Metal-Organic framework nanosheets for efficient photocatalytic CO2 transformation

2D metal − organic framework (MOF) nanosheets have been demonstrated to exhibit excellent properties and prospects in various aspects, especially in photocatalysis. However, the design and direct preparation of 2D MOF photocatalyst is highly desirable but still challenging. Herein, a novel 2D porphyrin-based MOF Fe-DBP(Co), which is assembled by dicarboxylic porphyrin ligands and the unprecedented undecametallic ferric-oxo clusters, is designed and developed. The unique nanosheet morphology and assembled layered structure endows the photocatalyst with higher electron-hole separation efficiency and longer photogenerated carrier lifetime compared to the analogous MOFs. Consequently, Fe-DBP(Co) exhibits strikingly excellent and stable photocatalytic performance in CO2 cycloaddition, and the reaction rate of 103.2 mmol∙g−1∙h−1 is among the state-of-the-art cases for MOF-photocatalyzed CO2 cycloaddition. The underlying mechanism investigation suggested that photogenerated electrons transferred from CoDBP ligands to the Fe clusters, and the abundant electrons and holes promoted the generation of Fe(II) and Co(III) respectively, leading to excellent catalytic performance. This work proposes a new strategy to design and develop efficient MOF photocatalysts for photocatalytic transformation of CO2.

Temperature Dependent Operando High Energy Surface X-Ray Diffraction Studies of Pt(111) Oxidation

Platinum electrocatalysts are still widely used as cathode material in proton-exchange membrane fuel cells (PEMFC) because of their high ORR activity. However, their long-term stability is limited due to degradation processes. This degradation is partly caused by Pt oxidation and oxide reduction, which lead to irreversible surface restructuring and subsequently Pt dissolution. To increase the lifetime of PEMFCs it is mandatory to understand the mechanisms behind the degradation on an atomistic level. This requires studies by structure sensitive in situ methods, in particular, also studies at the elevated temperatures typically employed in PEMFCs operation.Previous studies revealed that in the initial stage of oxide formation Pt atoms are extracted out of the surface and form an ultra-thin oxide layer directly above the surface. This extraction is long known as place exchange [1], but the atomic-scale details of the surface oxide structure, the extraction mechanism, and especially the kinetics of the initial oxide growth were only recently clarified [2-7]. It was found that the structural arrangement of the Pt atoms within the surface oxide on the Pt(111) and the Pt(100) surface is distinctly different, leading to differences in the oxidation/reduction kinetics, the reversibility of the surface oxidation/reduction process, and the amount of Pt dissolution into the electrolyte.Recently, we performed fast operando high-energy surface X-ray diffraction (HESXRD) studies, in which we investigated the initial extraction of Pt atoms on Pt(111) during potential cycles. Surprisingly, it was found that the Pt extraction during the anodic sweep is largely independent of the potential sweep rate, although the peak cyclic voltammograms (CVs) associated with the charge transfer during surface oxidation showed a pronounced shift [7-9]. This suggests that the Pt extraction is a fast process, rather driven by potential and not directly coupled to the slow formation of surface oxygen species. However, the Pt extraction during the anodic sweep and the re-insertion during the cathodic sweep still exhibit significant hysteresis, indicating a complex multistep oxidation kinetics.Previous electrochemical studies of Pt(111) electrodes revealed that the described influence of oxidation/reduction kinetics and the reversibility of the charge transfer processes increase at elevated temperature [10]. However, the temperature dependence of the Pt extraction behavior is currently unknown, because all previous structural studies of oxide growth and reduction have been performed exclusively at room temperature.For the experiments at elevated temperatures we developed a new setup for HESXRD studies of single crystals, which combines a hanging meniscus electrochemical cell for operando X-ray diffraction measurements with an inductive heating device in a joint Ar-filled compartment. This setup allows direct (re-)preparation of the aligned Pt single crystals on the diffractometer. By this, the time between preparation and measurement is reduced down to a few minutes and sample transfer through air is rigorously avoided.Temperature-dependent HESXRD measurements at temperatures up to 343 K were performed at beamline ID31 of the European Synchrotron Radiation Facility. The simultaneously measured electrochemical current and X-ray intensity indicate kinetic shifts in the charge transfer but a rather temperature independent Pt extraction process.We gratefully acknowledge financial support by the Deutsche Forschungsgemeinschaft via project no. 418603497 and the BMBF via 05K19FK3 and 05K22FK1.