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The Azure Kinect represents the latest generation of Microsoft Kinect depth cameras. Of interest in this article is the depth and spatial accuracy of the Azure Kinect and how it compares to its predecessor, the Kinect v2. In one experiment, the two sensors are used to capture a planar whiteboard at 15 locations in a grid pattern with laser scanner data serving as ground truth. A set of histograms reveals the temporal-based random depth error inherent in each Kinect. Additionally, a two-dimensional cone of accuracy illustrates the systematic spatial error. At distances greater than 2.5 m, we find the Azure Kinect to have improved accuracy in both spatial and temporal domains as compared to the Kinect v2, while for distances less than 2.5 m, the spatial and temporal accuracies were found to be comparable. In another experiment, we compare the distribution of random depth error between each Kinect sensor by capturing a flat wall across the field of view in horizontal and vertical directions. We find the Azure Kinect to have improved temporal accuracy over the Kinect v2 in the range of 2.5 to 3.5 m for measurements close to the optical axis. The results indicate that the Azure Kinect is a suitable substitute for Kinect v2 in 3D scanning applications.

Rigorous electrokinetic results are key to understanding the reaction mechanisms in the electrochemical CO reduction reaction (CORR), however, most reported results are compromised by the CO mass transport limitation. In this work, we determined mass transport-free CORR kinetics by employing a gas-diffusion type electrode and identified dependence of catalyst surface speciation on the electrolyte pH using in-situ surface enhanced vibrational spectroscopies. Based on the measured Tafel slopes and reaction orders, we demonstrate that the formation rates of C 2+ products are most likely limited by the dimerization of CO adsorbate. CH 4 production is limited by the CO hydrogenation step via a proton coupled electron transfer and a chemical hydrogenation step of CO by adsorbed hydrogen atom in weakly (7 < pH < 11) and strongly (pH > 11) alkaline electrolytes, respectively. Further, CH 4 and C 2+ products are likely formed on distinct types of active sites. Electrokinetic results are key to understanding the mechanisms in electrochemical CO reduction reaction. Here, the authors determine mass transport free kinetics using a gas-diffusion electrode and identified dependence of copper surface speciation on the electrolyte pH using in situ surface enhanced spectroscopies.

Harnessing renewable electricity to drive the electrochemical reduction of CO 2 is being intensely studied for sustainable fuel production and as a means for energy storage. Copper is the only monometallic electrocatalyst capable of converting CO 2 to value-added products, e.g., hydrocarbons and oxygenates, but suffers from poor selectivity and mediocre activity. Multiple oxidative treatments have shown improvements in the performance of copper catalysts. However, the fundamental underpinning for such enhancement remains controversial. Here, we combine reactivity, in-situ surface-enhanced Raman spectroscopy, and computational investigations to demonstrate that the presence of surface hydroxyl species by co-electrolysis of CO 2 with low concentrations of O 2 can dramatically enhance the activity of copper catalyzed CO 2 electroreduction. Our results indicate that co-electrolysis of CO 2 with an oxidant is a promising strategy to introduce catalytically active species in electrocatalysis. While the electrochemical conversion of CO 2 to highly reduced products is unique to copper, there are still gaps in understanding copper catalysts’ efficacy. Here, authors find that co-electrolysis of CO 2 with O 2 can enhance copper’s catalytic activities.

Electroreduction of carbon dioxide to hydrocarbons and oxygenates on copper involves reduction to a carbon monoxide adsorbate followed by further transformation to hydrocarbons and oxygenates. Simultaneous improvement of these processes over a single reactive site is challenging due to the linear scaling relationship of the binding strength of key intermediates. Herein, we report improved electroreduction of carbon dioxide by exploiting a one-pot tandem catalysis mechanism based on computational and electrochemical investigations. By constructing a well-defined copper-modified silver surface, adsorbed carbon monoxide generated on the silver sites is proposed to migrate to surface copper sites for the subsequent reduction to methane, which is consistent with insights gained from operando attenuated total reflectance surface enhanced infrared absorption spectroscopic investigations. Our results provide a promising approach for designing carbon dioxide electroreduction catalysts to enable one-pot reduction of products beyond carbon monoxide and formate. Carbon dioxide can be electrocatalytically reduced to valuable fuels and chemicals, but is hindered by poor catalytic efficiency and selectivity. Here the authors report improved electrocatalytic conversion of carbon dioxide into methane using a tandem catalysis strategy.

Despite the growing importance of fluorinated organic compounds in drug development, there are no direct protocols for the fluorination of aliphatic C-H bonds using conveniently handled fluoride salts. We have discovered that a manganese porphyrin complex catalyzes alkyl fluorination by fluoride ion under mild conditions in conjunction with stoichiometric oxidation by iodosylbenzene. Simple alkanes, terpenoids, and even steroids were selectively fluorinated at otherwise inaccessible sites in 50 to 60% yield. Decalin was fluorinated predominantly at the C2 and C3 methylene positions. Bornyl acetate was converted to exo-5-fluoro-bornyl acetate, and 5α-androstan-17-one was fluorinated selectively in the A ring. Mechanistic analysis suggests that the regioselectivity for C-H bond cleavage is directed by an oxomanganese(V) catalytic intermediate followed by F delivery via an unusual manganese(IV) fluoride that has been isolated and structurally characterized.

Although the field of polymer solar cell has seen much progress in device performance in the past few years, several limitations are holding back its further development. For instance, current high-efficiency (>9.0%) cells are restricted to material combinations that are based on limited donor polymers and only one specific fullerene acceptor. Here we report the achievement of high-performance (efficiencies up to 10.8%, fill factors up to 77%) thick-film polymer solar cells for multiple polymer:fullerene combinations via the formation of a near-ideal polymer:fullerene morphology that contains highly crystalline yet reasonably small polymer domains. This morphology is controlled by the temperature-dependent aggregation behaviour of the donor polymers and is insensitive to the choice of fullerenes. The uncovered aggregation and design rules yield three high-efficiency (>10%) donor polymers and will allow further synthetic advances and matching of both the polymer and fullerene materials, potentially leading to significantly improved performance and increased design flexibility. Polymer solar cells promise a cost-effective way to harness solar energy, but cell performance is held back by limited choices of suitable materials. Here, Liu et al. demonstrate record cell efficiencies for multiple material combinations via a new approach of aggregation and morphology control.

The oxidative dehydrogenation of propane, primarily sourced from shale gas, holds promise in meeting the surging global demand for propylene. However, this process necessitates high operating temperatures, which amplifies safety concerns in its application due to the use of mixed propane and oxygen. Moreover, these elevated temperatures may heighten the risk of overoxidation, leading to carbon dioxide formation. Here we introduce a microchannel reaction system designed for the oxidative dehydrogenation of propane within an aqueous environment, enabling highly selective and active propylene production at room temperature and ambient pressure with mitigated safety risks. A propylene selectivity of over 92% and production rate of 19.57 mmol m Cu −2 h −1 are simultaneously achieved. This exceptional performance stems from the in situ creation of a highly active, oxygen-containing Cu catalytic surface for propane activation, and the enhanced propane transfer via an enlarged gas-liquid interfacial area and a reduced diffusion path by establishing a gas-liquid Taylor flow using a custom-made T-junction microdevice. This microchannel reaction system offers an appealing approach to accelerate gas-liquid-solid reactions limited by the solubility of gaseous reactant. The activation of propane at mild conditions is challenging. Now a microfluidic reaction system with a Cu microtube serving as both the catalyst and the microchannel reactor can selectively convert propane to propylene at room temperature and ambient pressure.

Organic molecules that contain alkyl-difluoromethyl moieties have received increased attention in medicinal chemistry, but their synthesis in a modular and late-stage fashion remains challenging. We report herein an efficient copper-catalyzed radical relay approach for the carbo-difluoromethylation of alkenes. This approach simultaneously introduces CF 2 H groups along with complex alkyl or aryl groups into alkenes with regioselectivity opposite to traditional CF 2 H radical addition. We demonstrate a broad substrate scope and a wide functional group compatibility. This scalable protocol is applied to the late-stage functionalization of complex molecules and the synthesis of CF 2 H analogues of bioactive molecules. Mechanistic studies and density functional theory calculations suggest a unique ligand effect on the reactivity of the Cu-CF 2 H species. Compounds that contain alkyl-difluoromethyl moieties are of interest for medicinal chemistry, but their synthesis is challenging. Here, the authors report a copper-catalyzed radical relay approach for the carbodifluoromethylation of alkenes that simultaneously introduces CF 2 H groups and complex alkyl or aryl groups into alkenes.

The electron transport layer (ETL) is a key component of regular perovskite solar cells to promote the overall charge extraction efficiency and tune the crystallinity of the perovskite layer for better device performance. The authors present a novel protocol of ETL engineering by incorporating a composition of the perovskite precursor, methylammonium chloride (MACl), or formamidine chloride (FACl), into SnO2 layers, which are then converted into the crystal nuclei of perovskites by reaction with PbI2. The SnO2‐embedded nuclei remarkably improve the morphology and crystallinity of the optically active perovskite layers. The improved ETL‐to‐perovskite electrical contact and dense packing of large‐grained perovskites enhance the carrier mobility and suppress charge recombination. The power conversion efficiency increases from 20.12% (blank device) to 21.87% (21.72%) for devices with MACl (FACl) as an ETL dopant. Moreover, all the precursor‐engineered cells exhibit a record‐high fill factor (82%). Methylammonium chloride (MACl) or formamidine chloride (FACl) of perovskite precursor is added into SnO2 electron transport layer (ETL) and reacts with PbI2 to form perovskite crystal nucleus, which improves the contact between SnO2 ETL and perovskite, as well as the morphology and crystallinity of perovskite layer, and greatly improves the fill factor (FF) of perovskite solar cells (PSCs).

Bacterial infections have become a fatal threat because of the abuse of antibiotics in the world. Various gold (Au)-based nanostructures have been extensively explored as antibacterial agents to combat bacterial infections based on their remarkable chemical and physical characteristics. Many Au-based nanostructures have been designed and their antibacterial activities and mechanisms have been further examined and demonstrated. In this review, we collected and summarized current developments of antibacterial agents of Au-based nanostructures, including Au nanoparticles (AuNPs), Au nanoclusters (AuNCs), Au nanorods (AuNRs), Au nanobipyramids (AuNBPs), and Au nanostars (AuNSs) according to their shapes, sizes, and surface modifications. The rational designs and antibacterial mechanisms of these Au-based nanostructures are further discussed. With the developments of Au-based nanostructures as novel antibacterial agents, we also provide perspectives, challenges, and opportunities for future practical clinical applications.