Cu^+-incorporated TiO_2 overlayer on Cu_2O nanowire photocathodes for enhanced photoelectrochemical conversion of CO_2 to methanol

In this paper, we report photoelectrochemical（PEC） conversion of carbon dioxide（CO_2） using photocathodes based on Cu_2O nanowires（NWs） overcoated with Cu~＋-incorporated crystalline TiO_2（TiO_2–Cu~＋ ）shell. Cu_2O NW photocathodes show remanent photocurrent of 5.3% after 30 min of PEC reduction of CO_2.After coating Cu_2O with TiO_2–Cu~＋ overlayer, the remanent photocurrent is 27.6%, which is an increase by5.2 fold. The charge transfer resistance of Cu_2O/TiO_2–Cu~＋ is 0.423 k/cm2, whereas Cu_2O photocathode shows resistivity of 0.781 k/cm2 under irradiation. Mott–Schottky analysis reveals that Cu~＋ species embedded in TiO_2 layer is responsible for enhanced adsorption of CO_2 on TiO_2 surface, as evidenced by the decrease of capacitance in the Helmholtz layer. On account of these electrochemical and electronic effects by the Cu~＋ species, the Faradaic efficiency（FE） of photocathodes reaches as high as 56.5% when TiO_2–Cu~＋ is added to Cu_2O, showing drastic increase from 23.6% by bare Cu_2O photocathodes.

Engineering vacancy and hydrophobicity of two-dimensional TaTe_(2)for efficient and stable electrocatalytic N_(2)reduction

Demand for ammonia continues to increase to sustain the growing global population.The direct electrochemical N2 reduction reaction(NRR)powered by renewable electricity offers a promising carbon-neutral and sustainable strategy for manufacturing NH3,yet achieving this remains a grand challenge.Here,we report a synergistic strategy to promote ambient NRR for ammonia production by tuning the Te vacancies(VTe)and surface hydrophobicity of two-dimensional TaTe_(2)nanosheets.Remarkable NH3 faradic efficiency of up to 32.2%is attained at a mild overpotential,which is largely maintained even after 100 h of consecutive electrolysis.Isotopic labeling validates that the N atoms of formed NH4+originate from N2.In situ X-ray diffraction indicates preservation of the crystalline structure of TaTe_(2)during NRR.Further density functional theory calculations reveal that the potential-determining step(PDS)is*NH_(2)+(H^(+)+e^(-))/NH3 on VTe-TaTe_(2)compared with that of*+N2+(H^(+)+e^(-))/*N-NH on TaTe_(2).We identify that the edge plane of TaTe_(2)and VTe serve as the main active sites for NRR.The free energy change at PDS on VTe-TaTe_(2)is comparable with the values at the top of the NRR volcano plots on various transition metal surfaces.

Electrocatalytic Reduction of CO_(2)to CO with Almost 100%Faradaic Efficiency Using Oxygen-Vacancy Enriched Two-Dimensional MgO

The design and development of cheap,abundant,and efficient electrocatalysts for selective CO_(2)electroreduction is highly desirable yet remains an ongoing challenge.Herein,we report on our discovery of the use of two-dimensional MgO rich in oxygen vacancies(VO)as an electrocatalyst for the efficient reduction of CO_(2)to yield CO in 1-butyl-3-methylimidazolium hexafluorophosphate dissolved in acetonitrile.The faradaic efficiency toward CO reaches as high as 99.6±0.24%with a current density of up to 40.8 mA cm−2.Density functional theory calculations illustrate that the introduction of VO in MgO substantially lowers the reaction-free energy for the transformation of ^(*)COO^(−) to ^(*)COOH,the potential determining step,which greatly boosts CO_(2)conversion efficiency.This work opens the way to realizing economic and efficient CO_(2)electrolysis of group II metals.

Comparative toxicity of silver nanoparticles and silver ions to Escherichia coli

With the increase in silver（Ag）-based products in our lives, it is essential to test the potential toxicity of silver nanoparticles（Ag NPs） and silver ions（Ag ions） on living organisms under various conditions. Here, we investigated the toxicity of Ag NPs with Ag ions to Escherichia coli K-12 strain under various conditions. We observed that both Ag NPs and Ag ions display antibacterial activities, and that Ag ions had higher toxicity to E. coli K-12 strain than Ag NPs under the same concentrations. To understand the toxicity of Ag NPs at a cellular level, reactive oxygen species（ROS） enzymes were detected for use as antioxidant enzymatic biomarkers. We have also studied the toxicity of Ag NPs and Ag ions under various coexistence conditions including： fixed total concentration, with a varied the ratio of Ag NPs to Ag ions; fixed the Ag NPs concentration and then increased the Ag ions concentration; fixed Ag ions concentration and then increasing the Ag NPs concentration.Exposure to Ag NPs and Ag ions clearly had synergistic toxicity; however, decreased toxicity（for a fixed Ag NPs concentration of 5 mg/L, after increasing the Ag ions concentration） to E. coli K-12 strain. Ag NPs and Ag ions in the presence of L-cysteine accelerated the bacterial cell growth rate, thereby reducing the bioavailability of Ag ions released from Ag NPs under the single and coexistence conditions. Further works are needed to consider this potential for Ag NPs and Ag ions toxicity across a range of environmental conditions.Environmental Significance Statement： As silver nanoparticles（Ag NPs）-based products are being broadly used in commercial industries, an ecotoxicological understanding of the Ag NPs being released into the environment should be further considered. Here, we investigate the comparative toxicity of Ag NPs and silver ions（Ag ions） to Escherichia coli K-12 strain, a representative ecotoxicological bioreporter. This study showed that toxicities of Ag NPs and Ag ions to E. coli K-12 strain display different relationships when existing individually or when coexisting, and in the presence of L-cysteine materials. These findings suggest that the toxicology research of nanomaterials should consider conditions when NPs coexist with and without their bioavailable ions.

Nanocrystalline low-silica X zeolite as an efficient ion-exchanger enabling fast radioactive strontium capture

NaA zeolite(Si/Al=1.00)has been commercially applied for capturing radioactive 90Sr^(2+)because of its high surface charge density,effectively stabilizing the multivalent cation.However,owing to its narrow micropore opening(4.0Å),large micron-sized crystallites,and bulkiness of hydrated Sr^(2+),the Sr^(2+)exchange over NaA has been limited by very slow kinetics.In this study,we synthesized nanocrystalline low-silica X by minimizing a water content in a synthesis gel and utilizing a methyl cellulose hydrogel as a crystal growth inhibitor.The resulting zeolite exhibited high crystallinity and Al-rich framework(Si/Al of approximately 1.00)with the sole presence of tetrahedral Al sites,which are capable of high Sr^(2+)uptake and ion selectivity.Meanwhile,the zeolite with a FAU topology has a much larger micropore opening size(7.4Å)and a much smaller crystallite size(~340 nm)than NaA,which enable significantly enhanced ion-exchange kinetics.Compared to conventional NaA,the nanocrystalline low-silica X exhibited remarkably increased Sr^(2+)-exchange kinetics(>18-fold larger rate constant)in batch experiments.Although both the nanocrystalline low-silica X and NaA exhibited comparable Sr^(2+)capacities under equilibrated conditions,the former demonstrated a 5.5-fold larger breakthrough volume than NaA under dynamic conditions,attributed to its significantly faster Sr^(2+)-exchange kinetics.

Tobacco as a promising crop for low-carbon biorefinery

Energy crops play a vital role in meeting future energy and chemical demands while addressing climate change.However,the idealization of lowcarbon workflows and careful consideration of cost-benefit equations are crucial for their more sustainable implementation.Here,we propose tobacco as a promising energy crop because of its exceptional water solubility,mainly attributed to a high proportion of water-soluble carbohydrates and nitrogen,less lignocellulose,and the presence of acids.We then designed a strategy that maximizes biomass conversion into bio-based products while minimizing energy and material inputs.By autoclaving tobacco leaves in water,we obtained a nutrient-rich medium capable of supporting the growth of microorganisms and the production of bioproducts without the need for extensive pretreatment,hydrolysis,or additional supplements.Additionally,cultivating tobacco on barren lands can generate sufficient biomass to produce approximately 573 billion gallons of ethanol per year.This approach also leads to a reduction of greenhouse gas emissions by approximately 76%compared to traditional corn stover during biorefinery processes.Therefore,our study presents a novel and direct strategy that could significantly contribute to the goal of reducing carbon emissions and global sustainable development compared to traditional methods.

Programmable polyketide biosynthesis platform for production of aromatic compounds in yeast

To accelerate the shift to bio-based production and overcome complicated functional implementation of natural and artificial biosynthetic pathways to industry relevant organisms,development of new,versatile,bio-based production platforms is required.Here we present a novel yeast-based platform for biosynthesis of bacterial aromatic polyketides.The platform is based on a synthetic polyketide synthase system enabling a first demonstration of bacterial aromatic polyketide biosynthesis in a eukaryotic host.

Perovskite synthesizability using graph neural networks

Perovskite is an important material type in geophysics and for technologically important applications.However,the number of synthetic perovskites remains relatively small.To accelerate the high-throughput discovery of perovskites,we propose a graph neural network model to assess their synthesizability.Our trained model shows a promising 0.957 out-of-sample true positive rate,significantly improving over empirical rule-based methods.Further validation is established by demonstrating that a significant portion of the virtual crystals that are predicted to be synthesizable have already been indeed synthesized in literature,and those with the lowest synthesizability scores have not been reported.While previous empirical strategies are mainly applicable to metal oxides,our model is general and capable of predicting the synthesizability across all classes of perovskites,including chalcogenide,halide,and hydride perovskites,as well as anti-perovskites.We apply the method to identify synthesizable perovskite candidates for two potential applications,the Li-rich ion conductors and metal halide optical materials that can be tested experimentally.

CRISPy-web: An online resource to design sgRNAs for CRISPR applications

CRISPR/Cas9-based genome editing has been one of the major achievements of molecular biology,allowing the targeted engineering of a wide range of genomes.The system originally evolved in prokaryotes as an adaptive immune system against bacteriophage infections.It now sees widespread application in genome engineering workflows,especially using the Streptococcus pyogenes endonuclease Cas9.To utilize Cas9,so-called single guide RNAs(sgRNAs)need to be designed for each target gene.While there are many tools available to design sgRNAs for the popular model organisms,only few tools that allow designing sgRNAs for non-model organisms exist.Here,we present CRISPy-web(http://crispy.secondarymetabolites.org/),an easy to use web tool based on CRISPy to design sgRNAs for any userprovided microbial genome.CRISPy-web allows researchers to interactively select a region of their genome of interest to scan for possible sgRNAs.After checks for potential off-target matches,the resulting sgRNA sequences are displayed graphically and can be exported to text files.All steps and information are accessible from a web browser without the requirement to install and use command line scripts.