Selective Photocatalytic Reduction of CO2 to CO Mediated by Silver Single Atoms Anchored on Tubular Carbon Nitride.

Artificial photosynthesis is a promising strategy for converting carbon dioxide (CO2 ) and water (H2 O) into fuels and value-added chemical products. However, photocatalysts usually suffered from low activity and product selectivity due to the sluggish dynamic transfer of photoexcited charge carriers. Herein, we describe anchoring of Ag single atoms on hollow porous polygonal C3 N4 nanotubes (PCN) to form the photocatalyst Ag1 @PCN with Ag-N3 coordination for CO2 photoreduction using H2 O as the reductant. The as-synthesized Ag1 @PCN exhibits a high CO production rate of 0.32 µmol h-1 (mass of catalyst: 2 mg), a high selectivity (>94 %), and an excellent stability in the long term. Experiments and density functional theory (DFT) reveal that the strong metal-support interactions (Ag-N3 ) favor *CO2 adsorption, *COOH generation and desorption, and accelerate dynamic transfer of photoexcited charge carriers between C3 N4 and Ag single atoms, thereby accounting for the enhanced CO2 photoreduction activity with a high CO selectivity. This work provides a deep insight into the important role of strong metal-support interactions in enhancing the photoactivity and CO selectivity of CO2 photoreduction.

Designing Carbonized Loofah Sponge Architectures with Plasmonic Cu Nanoparticles Encapsulated in Graphitic Layers for Highly Efficient Solar Vapor Generation.

Solar vapor generation represents a promising approach to alleviate water shortage for producing fresh water from undrinkable water resources. Although Cu-based plasmonics have attracted tremendous interest due to efficient light-to-heat conversion, their application faces great challenges in the oxidation resistance of Cu and low evaporation rate. Herein, a hybrid of three-dimensional carbonized loofah sponges and graphene layers encapsulated Cu nanoparticles is successfully synthesized via a facile pyrolysis method. In addition to effective light harvesting, the localized heating effect of stabilized Cu nanoparticles remarkably elevated the surface temperature of Cu@C/CLS to 72 °C, and a vapor generation rate as high as 1.54 kg m-2 h-1 with solar thermal efficiency reaching 90.2% under 1 Sun illumination was achieved. A study in the purification of sewage and muddy water with Cu@C/CLS demonstrates a promising perspective in a practical application. These results may offer a new inspiration for the design of efficient nonprecious Cu-based photothermal materials.

Boron Dopant Induced Electron-Rich Bismuth for Electrochemical CO2 Reduction with High Solar Energy Conversion Efficiency.

Electrochemical CO2 reduction to formate offers a mild and feasible pathway for the utilization of CO2 , and bismuth is a promising metal for its unique hydrogen evolution reaction inhibition. Reported works of Bi-based electrodes generally exhibit high selectivity while suffering from relatively narrow working potential range. From the perspective of electronic modification engineering, B-doped Bi is prepared by a facile chemical reduction method in this work. With B dopant, above 90% Faradaic efficiency for formate over a broad window of working potential of -0.6 to -1.2 V (vs. reversible hydrogen electrode) is achieved. In situ Raman spectroscopy, X-ray adsorption spectroscopy, and computational analysis demonstrate that the B dopant induces the formation of electron-rich bismuth, which is in favor of the formation of formate by fine-tuning the adsorption energy of *OCHO. Moreover, full-cell electrolysis system coupled with photovoltaic device is constructed and achieves the solar-to-formate conversion efficiency as high as 11.8%.

Synthesis of Surface-Oxygen-Vacancy-Rich (GaN)0.5(ZnO)0.5 Particles with Enhanced Visible-Light Photodegradation Performance.

In this study, zinc-gallium oxynitrides with a Zn:Ga mole ratio of 1:1 [(GaN)0.5(ZnO)0.5] were synthesized from a Zn/Ga/CO3 layered double hydroxide (LDH) precursor. The microstructure and photoactivity of the (GaN)0.5(ZnO)0.5 particles were tuned by adjusting the nitridation conditions of the LDH. It is revealed that the quantity of the LDH, or, equivalently, the partial pressure of the water during nitridation, plays a pivotal role in the defect structure of the obtained oxynitrides. A reduction in the quantity of the LDH precursor can effectively suppress the formation of defects including Ga(Zn)-O bonding, bulk anion vacancies, and surface-deposited Ga/ON···VGa complexes, leading to a better charge-separation efficiency for the photogenerated electron-hole pairs in the oxynitride. Furthermore, a suitable introduction of methane during nitridation would not only increase the crystallinity of the bulk materials but also enhance the density of the surface oxygen vacancy (VO), which would raise the charge-injection efficiency by working as an electron trap and a reaction site to form O2•-. O2•-, as well as photogenerated holes, have been proven to be the dominant active species for the photodegradation of phenol. 25CH4-ZnGaNO, with the lowest density of bulk defects and the highest density of surface VO, exhibited the best photoactivity under visible-light irradiation for the photodegradation of Rhodamine B and phenol. The obtained surface-VO-rich (GaN)0.5(ZnO)0.5 particles can be applied as a high-performance visible-light-driven photocatalyst in the photodegradation of organic pollutants.

The pollution levels, variation characteristics, sources and implications of atmospheric carbonyls in a typical rural area of North China Plain during winter.

Atmospheric carbonyls were measured at a typical rural area of the North China Plain (NCP) from November 13 to December 24, 2017 to investigate the pollution characteristics, sources and environmental implications. Fifteen carbonyls were detected, and formaldehyde, acetaldehyde and acetone accounted for about 81% at most. The concentration of the total carbonyls in heavily polluted days was twice more than that in clean days. In contrast to other carbonyls, m-tolualdehyde exhibited relatively high concentrations in the clean days in comparison with the polluted days. The ratios of three principal carbonyls to CO showed similar daily variations at different pollution levels with significant daytime peaks. Multiple linear regression analysis revealed that the contributions of background, primary and secondary sources to three principal carbonyls showed similar variation trends from the clean level to the heavily polluted level. The OH formation rate of formaldehyde showed a similar variation trend to its photodegradation rate, reaching the peak value at noon, which is important to maintain relatively high OH levels to initiate the oxidation of various gas-phase pollutants for secondary pollutant formation at the rural site. OH radical consumption rate and ozone formation potential (OFP) calculations showed that formaldehyde and acetaldehyde were the dominant oxidative species among measured carbonyls. As for OH radical consumption, n-butyraldehyde and m-tolualdehyde were important contributors, while for ozone formation potential, n-butyraldehyde and propionaldehyde made significant contributions. In addition, the contribution of carbonyl compounds to secondary organic aerosol (SOA) formation was also important and needs further investigation.

CO tolerance of Pt/FeOx catalyst in both thermal catalytic H2 oxidation and electrochemical CO oxidation: the effect of Pt deficit electron state.

CO poisoning of Pt catalysts is one of the major challenges to the commercialization of proton exchange membrane fuel cells. One promising solution is to develop CO-tolerant Pt-based catalysts. A facilely synthesized Pt/FeOx catalyst exhibited outstanding CO tolerance in the oxidation of H2 and electrochemical CO stripping. Light-off temperature of H2O formation over Pt/FeOx was achieved even below 30 °C in the presence of 3000 ppm CO at a space velocity of 18 000 mL g-1cat h-1. For the electrochemical oxidation of CO, the onset and peak potentials decreased by 0.17 V and 0.10 V, respectively, in comparison with those of commercial Pt/C. More importantly, by a combination of hard X-ray photoemission spectroscopy and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) studies it was found that the decreased electron density of Pt in Pt/FeOx enhanced the mobility of adsorbed CO, suppressed Pt-CO bonding and significantly increased the CO tolerance of Pt/FeOx.

Porous-structured Cu2O/TiO2 nanojunction material toward efficient CO2 photoreduction.

Porous-structured Cu2O/TiO2 nanojunction material is successfully fabricated by a facile method via loading Cu2O nanoparticles on the network of a porous TiO2 substrate. The developed Cu2O/TiO2 nanojunction material has a size of several nanometers, in which the p-type Cu2O and n-type TiO2 nanoparticles are closely contacted with each other. The well designed nanojunction structure is beneficial for the charge separation in the photocatalytic reaction. Meanwhile, the porous structure of the Cu2O/TiO2 nanojunction can facilitate the CO2 adsorption and offer more reaction active sites. Most importantly, the gas-phase CO2 photoreduction tests reveal that our developed porous-structured Cu2O/TiO2 nanojunction material exhibits marked photocatalytic activity in the CH4 evolution, about 12, 9, and 7.5 times higher than the pure TiO2, Pt-TiO2, and commercial Degussa P25 TiO2 powders, respectively. The greatly enhanced activity can be attributed to the well designed nanojunction structure combined with the porous structure, which can simultaneously enhance the charge separation efficiency and facilitate the CO2 adsorption.

Optimization system for training efficiency and load balance based on the fusion of heart rate and inertial sensors.

Objectives: To enhance the daily training quality of athletes without inducing significant physiological fatigue, aiming to achieve a balance between training efficiency and load. Design methods: Firstly, we developed an activity classification training model using the random forest algorithm and introduced the "effective training rate" (the ratio of effective activity time to total time) as a metric for assessing athlete training efficiency. Secondly, a method for rating athlete training load was established, involving qualitative and quantitative analyses of physiological fatigue through subjective fatigue scores and heart rate data. Lastly, an optimization system for training efficiency and load balance, utilizing multiple inertial sensors, was created. Athlete states were categorized into nine types based on the training load and efficiency ratings, with corresponding management recommendations provided. Results: Overall, this study, combining a sports activity recognition model with a physiological fatigue assessment model, has developed a training efficiency and load balance optimization system with excellent performance. The results indicate that the prediction accuracy of the sports activity recognition model is as high as 94.70%. Additionally, the physiological fatigue assessment model, utilizing average relative heart rate and average RPE score as evaluation metrics, demonstrates a good overall fit, validating the feasibility of this model. Conclusions: This study, based on relative heart rate and wearable devices to monitor athlete physiological fatigue, has developed a balanced optimization system for training efficiency and load. It provides a reference for athletes' physical health and fatigue levels, offering corresponding management recommendations for coaches and relevant professionals.

Perforating and ophthalmic artery variants from the anterior cerebral artery: Two case reports.

BACKGROUND: The diagnosis and therapy during surgery depend largely on a full account of anatomic characteristics. Apart from regular structures, the common, less common or even uncommon anatomic variations are critical for procedural planning. This is especially true during craniocerebral microsurgery, where small vascular variations can affect the final surgical results and patient prognosis. CASE SUMMARY: Herein, two rare variations concerning the A1 (horizontal) segment of anterior cerebral artery (ACA1) were introduced. One enabled the communication between perforating branch of ACA1 and dural artery of anterior skull base, which was discovered during autopsy. The other was ophthalmic artery (OA) originating from ACA1, shown on digital angiography. CONCLUSION: In this study, we found two rare anatomical variations. One was an abnormal OA originated from the anterior communicating artery. The other was a perforating branch of the A1 segment of the anterior cerebral artery, which communicated with meningeal vessels in the anterior skull base. This finding is of great significance for the treatment of anterior communicating artery aneurysm or in other anterior skull base surgery.

Organic Molecule Bifunctionalized Polymeric Carbon Nitride for Enhanced Photocatalytic Hydrogen Peroxide Production.

Modifying the polymeric carbon nitride (CN) with organic molecules is a promising strategy to enhance the photocatalytic activity. However, most previously reported works show that interchain embedding and edge grafting of the organic molecule can hardly be achieved simultaneously. Herein, we successfully synthesized organic molecule bifunctionalized CN (MBCN) through copolymerization of melon and sulfanilamide at a purposely elevated temperature of 550 °C. In MBCN, the edge grafted and interchain embedded benzene rings act as the electron-donating group and charge-transfer channel, respectively, rendering efficient photocatalytic H2 O2 production. The optimal MBCN exhibits a significantly improved non-sacrificial photocatalytic H2 O2 generation rate (54.0 µmol g-1 h-1 ) from pure water, which is 10.4 times that of pristine CN. Experimental and density functional theory (DFT) calculation results reveal that the enhanced H2 O2 production activity of MBCN is mainly attributed to the improved photogenerated charge separation/transfer and decreased formation energy barrier (▵G) from O2- to the intermediate 1,4-endoperoxide (⋅OOH). This work suggests that simultaneous formation of electron donating group and charge transfer channel via organic molecule bifunctionalization is a feasible strategy for boosting the photocatalytic activity of CN.

Promoting water dissociation for efficient solar driven CO2 electroreduction via improving hydroxyl adsorption.

Exploring efficient electrocatalysts with fundamental understanding of the reaction mechanism is imperative in CO2 electroreduction. However, the impact of sluggish water dissociation as proton source and the surface species in reaction are still unclear. Herein, we report a strategy of promoting protonation in CO2 electroreduction by implementing oxygen vacancy engineering on Bi2O2CO3 over which high Faradaic efficiency of formate (above 90%) and large partial current density (162 mA cm-2) are achieved. Systematic study reveals that the production rate of formate is mainly hampered by water dissociation, while the introduction of oxygen vacancy accelerates water dissociation kinetics by strengthening hydroxyl adsorption and reduces the energetic span of CO2 electroreduction. Moreover, CO3* involved in formate formation as the key surface species is clearly identified by electron spin resonance measurements and designed in situ Raman spectroscopy study combined with isotopic labelling. Coupled with photovoltaic device, the solar to formate energy conversion efficiency reaches as high as 13.3%.

Wafer-level photocatalytic water splitting on GaN nanowire arrays grown by molecular beam epitaxy.

We report on the achievement of wafer-level photocatalytic overall water splitting on GaN nanowires grown by molecular beam epitaxy with the incorporation of Rh/Cr(2)O(3) core-shell nanostructures acting as cocatalysts, through which H(2) evolution is promoted by the noble metal core (Rh) while the water forming back reaction over Rh is effectively prevented by the Cr(2)O(3) shell O(2) diffusion barrier. The decomposition of pure water into H(2) and O(2) by GaN nanowires is confirmed to be a highly stable photocatalytic process, with the turnover number per unit time well exceeding the value of any previously reported GaN powder samples.

Effect of external stress on the microstructure and mechanical properties of creep-aged Al-Cu-Li-Ag alloy.

The effects of external stress on the precipitation of T1 precipitates and mechanical properties of creep-aged Al-Cu-Li-Ag alloys are investigated. Promotion mechanisms of external stress to the precipitation of T1 precipitates are discussed. It is found that external stress significantly promotes the precipitation and improves the distribution of the T1 precipitates in the creep-aged alloys. There is a threshold stress, close to the yield stress, that has only a limited promotion effect on the precipitation of T1 precipitates. The external stress below and above the threshold stress promotes the precipitation of T1 precipitates by two different mechanisms. One is the promotion mechanism of lattice distortion produced by the elastic stress. Another is the promotion mechanism of multiplication of dislocations produced by the plastic stress. Both elastic and plastic external stress can synergistically improve the strength and ductility. Especially, the plastic external stress resulted in the best improvement to ductility of creep-aged alloys. Hence, the creep ageing with plastic external stress is an alternative method to synergistically improve the strength and ductility of Al-Cu-Li-Ag alloys. However, it is necessary to avoid using excessive plastic stress for the creep ageing because it may cause creep damage and degrade its mechanical properties.

Efficient photocatalytic conversion of CH4 into ethanol with O2 over nitrogen vacancy-rich carbon nitride at room temperature.

A record ethanol production rate of 281.6 µmol g-1 h-1 for the photocatalytic conversion of methane over nitrogen vacancy-rich carbon nitride at room temperature was achieved. Systematic studies demonstrate that the CH4 was activated by the highly reactive ˙OH radicals generated, via H2O2, from the photo-reduction of O2 with H2O.

Effect of pre-strain on microstructure and micro-yield properties of Al-Cu-Li alloy.

In this study, Al-Cu-Li alloys were pre-strained to various plastic strains before ageing. The T1 (Al2CuLi) precipitates and dislocation density in various pre-strained Al-Cu-Li alloys were analyzed with transmission electron microscopy (TEM) and X-ray diffraction (XRD) technology respectively. The micro-yield strength (Micro-YS) of tested alloys was measured and the strengthening mechanism was discussed. It is found that the pre-strain increases the dislocation density, promotes the precipitation and inhibits the growth of T1 precipitates. The precipitation strengthening of T1 precipitates is higher than strain strghening of dislocations and it first increase then decrease whearas the strain strenthening continuously increase with pre-strain. The improvement in strength of Al-Cu-Li alloy caused by pre-straining is mainly due to strain strengthening rather than precipitation strengthening. Therefore, although pre-strain improves the macro-yield strength (Macro-YS) as well as the Micro-YS, excessive pre-strains are not conducive to the improvement of the Micro-YS. The pre-strain of 2% is a promising method to simultaneously improve the Micro-YS and Macro-YS of Al-Cu-Li alloys due to its synergistic improvement effect on precipitation strengthening and strain strengthening. Macro-YS and Micro-YS of pre-strained Al-Cu-Li alloys can be estimated with a simple strength mode. However, the larger error between the estimated and measured Micro-YS suggests that the accurate estimation of Micro-YS requires further to consider the adverse effect of mobile dislocations caused by pre-strain on the Micro-YS.

Effect of ball milling process on the mechanical and thermal properties of the nanodiamond/2024Al composites.

In this study, 5 wt.% nanodiamond (ND) reinforced 2024Al matrix composites (ND/2024Al) were fabricated with various ball milling processes. The microstructure, compressive yield strength (σyc) and coefficient of thermal expansion (CTE) of ND/2024Al composites were investigated. It is found that the addition of 5 wt.% NDs significantly increases the σyc and decreases the CTE of 2024Al. High energy ball milling further increases σyc and decreases CTEs of ND/2024Al composite due to it enhances the fine grain strengthening of α-Al matrix and the dispersion strengthening of NDs, decreases the thermal mismatch stress at the ND/α-Al matrix interface, and increases the constraint of NDs on α-Al. The composites fabricated by the combinations of ball milling speeds and times of (5-7) h×(200-250)rpm and 9 h×300 rpm have the highest σyc and the lowest CTE respectively. Considering the different influence of ball milling parameters on σyc and CTEs, a evaluation coefficient α=σycC⋅εkcCσycM⋅εkcM⋅CTEMCTEC is proposed to evaluate the synergistic influence of mechanical properties and CTEs on the dimensional stability of ND/2024Al composites. Large value of α may lead to high dimensional stability of material, hence the α can be used to determine the ball milling parameters.The ball milling process of 250-300 rpm ball milling speeds and 5-7 h ball milling times are recommended based on α, which causes a 95-100 % increase in σyc and a 30-35 % decrease in CTE compared with 2024Al alloy, respectively.

Zr-Al co-doped SrTiO3 with suppressed charge recombination for efficient photocatalytic overall water splitting.

Zr-Al co-doped SrTiO3 with reduced Ti3+ concentration demonstrates more than 2 times enhancement compared with Al-doped SrTiO3 in photocatalytic overall water splitting. Systematic studies reveal that the co-doping of Zr4+ can reduce the substitution of Ti4+ by Al3+ and effectively suppress the formation of charge carrier recombination centers (Ti3+).

Cl- modification for effective promotion of photoelectrochemical water oxidation over BiVO4.

Postsynthetic treatment is an attractive method to enhance photoelectrochemical water splitting. The facile Cl- modification approach developed in this work remarkably promotes the photocurrent density of BiVO4 up to 2.7 mA cm-2 by facilitating carrier transfer in addition to a charge carrier separation efficiency enhancement.

Conformal BiVO4-Layer/WO3-Nanoplate-Array Heterojunction Photoanode Modified with Cobalt Phosphate Cocatalyst for Significantly Enhanced Photoelectrochemical Performances.

Constructing semiconductor heterojunctions via surface/interface engineering is an effective way to enhance the charge carrier separation/transport ability and thus the photoelectrochemical (PEC) properties of a photoelectrode. Herein, we report a conformal BiVO4-layer/WO3-nanoplate-array heterojunction photoanode modified with cobalt phosphate (Co-Pi) as oxygen evolution cocatalyst (OEC) for significant enhancement in PEC performances. The BiVO4/WO3 nanocomposite is fabricated by coating a thin conformal BiVO4 layer on the surface of presynthesized WO3 nanoplate arrays (NPAs) via stepwise spin-coating, and the decoration of Co-Pi OEC is realized by photoassisted electrodeposition method. The optimized Co-Pi@BiVO4/WO3 heterojunction photoanode shows a maximum photocurrent of 1.8 mA/cm2 at 1.23 V vs RHE in a phosphate buffer electrolyte under an AM1.5G solar simulator, which is 5 and 12 times higher than those of bare WO3 and BiVO4 photoanode, respectively. Measurements of UV-vis absorption spectra, electrochemical impedance spectra (EIS) and photoluminescence (PL) spectra reveal that the enhanced PEC performances can be attributed to the increased charge carrier separation/transport benefited from the type II nature of BiVO4/WO3 heterojunction and the promoted water oxidation kinetics and photostability owing to the decoration of Co-Pi cocatalyst.

Copper nanoparticles selectively encapsulated in an ultrathin carbon cage loaded on SrTiO3 as stable photocatalysts for visible-light H2 evolution via water splitting.

One-nanometre-thick carbon cage encapsulated copper nanopaticles on SrTiO3 (STO) synthesized through a facile chemical vapour deposition method showed remarkable stability and performance for both photocatalytic hydrogen evolution and thermocatalytic reduction of 4-nitrophenol. X-ray photoelectron spectroscopy and Raman results demonstrate that the graphene cage effectively protected Cu nanoparticles from being oxidized.