Customizing pyridinic nitrogen coordination in Ni-N-C for electrocatalytic CO2reduction towards CO.

Nickel anchored N-doped carbon electrocatalysts (Ni-N-C) are rapidly developed for the electrochemical reduction reaction of carbon dioxide (CO2RR). However, the high-performanced Ni-N-C analogues design for CO2RR remains bewilderment, for the reason lacking of definite guidance for its structure-activity relationship. Herein, the correlation between the proportion of nitrogen species derived from various nitrogen sources and the CO2RR activity of Ni-N-C is investigated. The x-ray photoelectron spectroscopy (XPS) spectrum combined with the CO2RR performance results show that pyridinic-N content has a positive correlation with CO2RR activity. Moreover, density functional theory (DFT) demonstrates that pyridinic-N coordinated Ni-N4sites offers optimized free energy and favorable selectivity towards CO2RR compared with pyrrolic-N. Accordingly, Ni-Na-C with highest pyridinic-N content (ammonia as nitrogen source) performs superior CO2RR activity, with the maximum carbon monoxide faradaic efficiency (FECO) of 99.8% at -0.88 V vs. RHE and the FECOsurpassing 95% within potential ranging of -0.88 to -1.38 V vs. RHE. The building of this parameter for CO2RR activity of Ni-N-C give instructive forecast for low-cost and highly active CO2RR electrocatalysts.

Three-dimensional ordered macroporous design of heterogeneous cobalt-iron phosphides as oxygen evolution electrocatalyst.

Oxygen evolution reaction (OER) plays a key role in electrochemical conversion, which needs efficient and economical electrocatalyst to boost its kinetics for large-scale application. Herein, a bimetallic CoP/FeP2heterostructure with a three-dimensional ordered macroporous structure (3DOM-CoP/FeP2) was synthesized as an OER catalyst to demonstrate a heterogeneous engineering induction strategy. By adjusting the electron distribution and producing a lot of active sites, the heterogeneous interface enhances catalytic performance. High specific surface area is provided by the 3DOM structure. Additionally, at the solid-gas-electrolyte threephase interface, the electrocatalytic reaction exhibits good mass transfer.In situRaman spectroscopy characterization revealed that FeOOH and CoOOH reconstructed from CoP/FeP2were the true OER active sites. Consequently, the 3DOM-CoP/FeP2demonstrates superior OER activity with a low overpotentials of 300/420 mV at 10/100 mA cm-2and meritorious OER durability. It also reveals promising performance as the overall water splitting anode.

Protective Cerium Oxide Coating Promoted Ce-Doping and Reconstruction of High-Valence NiFe Sulfide toward Robust Overall Water Splitting.

Active and stable electrocatalysts toward oxygen evolution reaction (OER) are essential for alkaline water splitting. Herein, an efficient and durable high-valence NiFe-based OER electrocatalyst is developed, featuring a protective CeO2- x coating to prevent the corrosion of carbon substrates during oxidative OER operation, ensuring excellent catalyst stability. The incorporation of a CeO2- x coating also leads to the formation of a Ce-doped NiFe sulfide catalyst. The Ce modulator enables the dynamic transformation of NiFe sulfide into highly active (oxy)hydroxide species with high-valence Ni sites and enhanced Ni─O covalency, thereby improving its OER catalytic activity. Accordingly, the prepared NiFeS2 /CeO2- x /CC catalyst achieves enhanced OER activity with an overpotential of 260 mV at 100 mA cm-2 in 1.0 m KOH. Moreover, the catalyst achieves 100 mA cm-2 current density at an overpotential of 187 mV for the hydrogen evolution reaction. The anion exchange membrane water electrolyzer reached 500 mA cm-2 at 1.73 V cell voltage with excellent stability for 500 h continuous operation. This study demonstrates a promising approach for the fabrication of robust water-splitting electrocatalysts.

Biological toxicity effects of florfenicol on antioxidant, immunity and intestinal flora of zebrafish (Danio rerio).

The accumulation of antibiotics in the aquatic environment is increasingly becoming a risk to the health of aquatic animal. The purpose of this study was to investigate the acute and chronic toxicity of florfenicol (FF) to zebrafish. A 56-day chronic toxicity test followed a 96-h acute toxicity test. The chronic toxicity test was divided into five FF concentration groups: 0 mg/L (C), 5 mg/L (T5), 10 mg/L (T10), 20 mg/L (T20) and 40 mg/L (T40). Each group had five replicates, with 20 Zebrafish per replicate. The acute toxicity test results showed that the 96 h-LC50 of FF was greater than 2000 mg/L, indicating low toxicity. The exposure concentrations of FF exceeding 20 mg/L can cause oxidative damage to the liver and gill tissues of fish, leading to the accumulation of oxidative products in the tissues and severe damage to antioxidant capacity. The reactive oxygen species (ROS) generated by severe oxidative stress activates the toll like receptors (TLR) pathway, inducing inflammation in the liver and gill tissues, stimulating the upregulation of inflammatory factor expression levels, and leading to immune system disorders. FF exposure at a concentration of 5 mg/L can lead to a significant decrease in the diversity and evenness of gut microbiota. The concentration of FF in water bodies above 37.52 mg/L poses a potential risk to aquatic products.

A 7.4-Bit ENOB 600 MS/s FPGA-Based Online Calibrated Slope ADC without External Components.

A slope analog-to-digital converter (ADC) amenable to be fully implemented on a digital field programmable gate array (FPGA) without requiring any external active or passive components is proposed in this paper. The amplitude information, encoded in the transition times of a standard LVDS differential input-driven by the analog input and by the reference slope generated by an FPGA output buffer-is retrieved by an FPGA time-to-digital converter. Along with the ADC, a new online calibration algorithm is developed to mitigate the influence of process, voltage, and temperature variations on its performance. Measurements on an ADC prototype reveal an analog input range from 0.3 V to 1.5 V, a least significant bit (LSB) of 2.6 mV, and an effective number of bits (ENOB) of 7.4-bit at 600 MS/s. The differential nonlinearity (DNL) is in the range between -0.78 and 0.70 LSB, and the integral nonlinearity (INL) is in the range from -0.72 to 0.78 LSB.

Correction: Zhang et al. A 7.4-Bit ENOB 600 MS/s FPGA-Based Online Calibrated Slope ADC without External Components. Sensors 2022, 22, 5852.

The authors wish to correct the following errors in the original paper [...].

Cobalt Element Effect of Ternary Mesoporous Cerium Lanthanum Solid Solution for the Catalytic Conversion of Methanol and CO2 into Dimethyl Carbonate.

A citric acid ligand assisted self-assembly method is used for the synthesis of ternary mesoporous cerium lanthanum solid solution doped with metal elements (Co, Zr, Mg). Their textural property was characterized by X-ray diffraction, transmission electron microscopy, N2 adsorption-desorption, X-ray photoelectron spectroscopy and TPD techniques, and so on. The results of catalytic testing for synthesis of dimethyl carbonate (DMC) from CH3OH and CO2 indicated that the DMC yield reached 316 mmol/g on Ce-La-Co solid solution when the reaction temperature was 413 K and the reaction pressure was 8.0 MPa. It was found that Co had synergistic effect with La and Ce, doping of Co on the mesoporous Ce-La solid solution was helpful to increase the surface area of the catalyst, promote CO2 adsorption and activation, and improve the redox performance of solid solution catalyst. The conversion of Co2+ to Co3+ resulted in the continuous redox cycle between Ce4+ and Ce3+, and the oxygen vacancy content of the catalyst was increased. Studies have shown that the catalytic performance of Ce-La-Co solid solution is positively correlated with oxygen vacancy content. On this basis, the reaction mechanism of DMC synthesis from CO2 and CH3OH on the catalyst was speculated.

Co-Production of Dimethyl Carbonate, Dimethoxymethane and Dimethyl Ether from Methanol: Process Design and Exergy Analysis.

Dimethyl carbonate is an important green chemical that has been widely used in the chemical industry. In the production of dimethyl carbonate, methanol oxidative carbonylation has been studied, but the conversion ratio of dimethyl carbonate using this method is too low, and the subsequent separation requires a large amount of energy due to methanol and dimethyl carbonate being azeotrope. In this paper, the strategy of "reaction instead of separation" is proposed. Based on this strategy, a novel process is developed to combine the production of DMC with that of dimethoxymethane (DMM) and dimethyl ether (DME). The co-production process was simulated using Aspen Plus software, and the product purity was up to 99.9%. The exergy analysis of the co-production process and the existing process was carried out. The exergy destruction and exergy efficiency were compared with those of the existing production processes. The results show that the exergy destruction of the co-production process is about 276% less than that of the single-production processes, and the exergy efficiencies in the developed co-production process are significantly improved. The utility loads of the co-production process are significantly lower than that of the single-production process. The developed co-production process increases the methanol conversion ratio to 95%, with a reduced energy requirement. It is proved that the developed co-production process can provide an advantageous option over the existing processes with improved energy efficiency and material savings. The strategy of "reaction instead of separation" is feasible. A new strategy is proposed for azeotrope separation.

ZIF-67-derived N-doped double layer carbon cage as efficient catalyst for oxygen reduction reaction.

The slow kinetic of oxygen reduction reaction (ORR) hampers the practical application of energy conversion devices, such as fuel cells, metal-air batteries. Here, an efficient ORR electrocatalyst consists of Co, Ni co-decorated nitrogen-doped double shell hollow carbon cage (Ni-Co@NHC) was fabricated by pyrolyzing Ni-doped polydopamine wrapped ZIF-67. During the preparation, polydopamine served as a protective layer can effectively prevent the aggregation of Co and Ni nanoparticles during the pyrolysis process, and at the same time forming a carbon layer to grow a double layer carbon cage. This unique hollow structure endows the catalyst with a high specific surface area as well as more exposed active sites. Also benefited from the synergistic effect between Ni and Co nanoparticles, the Ni-Co@NHC catalyst leads to an outstanding ORR performance of half-wave potential (E1/2, 0.862 V), outperforms that of commercial Pt/C catalyst. Additionally, when Ni-Co@NHC was used in the cathode for the zinc-air battery, the cell exhibits high power density (108 mW cm-2) and high specific capacity (806 mAh g-1) at 20 mA cm-2outperforming Pt/C. This work offers a promising design strategy for the development of high-performance ORR electrocatalysts.

Surface-engineered cobalt nitride composite as efficient bifunctional oxygen electrocatalyst.

Efficient and low-cost bifunctional catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are essential for the practical application of rechargeable metal-air batteries. In this work, we developed an efficient cobalt nitride hybrid bifunctional electrocatalyst, which consists of sulfur-doped and mildly oxidized Co5.47N nanoparticles supported on nitrogen-doped reduced graphene oxide sheet (O-S-Co5.47N@N-RGO). The composite exhibits good ORR-OER catalytic activity and excellent stability as well. It delivers an ORR half-wave potential of 0.82 V and an over-potential of 380 mV for OER at 10 mA cm-2 in 0.1 M KOH electrolyte. Density functional theory calculations indicate that the ORR activity of the composite might have originated from the Co-N4 site in the RGO sheet, whereas the surface Co sites on O-S-Co5.47N crystal are responsible for its OER activity. The facile preparation method and insight into the ORR-OER active sites reported in this study advances the development of high-performance bifunctional oxygen electrocatalyst.

Anion-Controlled Cation-Exchange Process: Intercalating α-Titanium Phosphate through Direct Ion Exchange with Alkylammonium Salts.

Several alkylammonium salts were used in the study of α-titanium phosphate (α-TiP) intercalation chemistry. The characterization results demonstrated that the expected intercalation by direct ion exchange could be successfully achieved without any addition of an extra amine substance. Our findings are different from the current opinion that by the ion-exchange method, without the assistance of bases, large cations are difficult to exchange into the narrow interlayer space of α-tetravalent metal phosphate directly because of the small interlayer distance. Studies found that alkylammonium cations, for example, n-butylammonium cation, could be directly exchanged into the interlayer space merely by choosing salts with appropriate anions such as phosphate, phosphite, sulfite, citrate, and malate ions. In the case of phosphates, besides n-butylammonium, the exchange of n-hexylammonium, cyclohexylammonium, and pyridinium with interlayer protons was investigated and successfully accomplished as well. The uptake values for these four cations were 0.420, 0.595, 0.571, and 0.335 g/g, respectively. A mechanism study revealed that although the relevant exchange reaction seemed only to involve the proton of α-TiP and the alkylammonium cation of the salt, the strength of the conjugate acid of the anion from the salt-the counterion-was proven to be the key factor in this process.

A novel technology coupling extraction and foam fractionation for separating the total saponins from Achyranthes bidentata.

A novel technology coupling extraction and foam fractionation was developed for separating the total saponins from Achyranthes bidentata. In the developed technology, the powder of A. bidentata was loaded in a nylon filter cloth pocket with bore diameter of 180 µm. The pocket was fixed in the bulk liquid phase for continuously releasing saponins. Under the optimal conditions, the concentration and the extraction rate of the total saponins in the foamate by the developed technology were 73.5% and 416.2% higher than those by the traditional technology, respectively. The foamates obtained by the traditional technology and the developed technology were analyzed by ultraperformance liquid chromatography-mass spectrometry to determine their ingredients, and the results appeared that the developed technology exhibited a better performance for separating saponins than the traditional technology. The study is expected to develop a novel technology for cost effectively separating plant-derived materials with surface activity.

How To Get Isocyanate?

Isocyanate, a pivotal chemical intermediate to synthesize polyurethane with widespread applications in household appliances, automobiles, and construction, is predominantly produced via the phosgene process, which currently holds a paramount status in industrial isocyanate production. Nonetheless, concerns arise from the toxicity of phosgene and the corrosiveness of hydrogen chloride, posing safety hazards. The synthesis of isocyanate using nonphosgene methods represents a promising avenue for future development. This article primarily focuses on the nonphosgene approach, which involves the formation of carbamate through the reaction of nitro-amino compounds with carbon monoxide, dimethyl carbonate, and urea, among other reagents, subsequently leading to the thermal decomposition of carbamate to get isocyanate. This paper emphasizes the progress in catalyst development during the carbamate decomposition process. Single-component metal catalysts, particularly zinc, exhibit advantages such as high activity, cost-effectiveness, and compatibility with a wide range of substrates. Composite catalysts enhance isocyanate yield by introducing a second component to adjust the active metal composition. The central research direction aims to optimize catalyst adaptation to reaction conditions, including temperature, pressure, time, and solvent, to achieve high raw material conversion and product yield.

Lattice Strain with Stabilized Oxygen Vacancies Boosts Ceria for Robust Alkaline Hydrogen Evolution Outperforming Benchmark Pt.

Earth-abundant metal oxides are usually considered as stable but catalytically inert toward hydrogen evolution reaction (HER) due to their unfavorable hydrogen intermediate adsorption performance. Herein, a heavy rare earth (Y) and transition metal (Co) dual-doping induced lattice strain and oxygen vacancy stabilization strategy is proposed to boost CeO2 toward robust alkaline HER. The induced lattice compression and increased oxygen vacancy (Ov) concentration in CeO2 synergistically improve the water dissociation on Ov sites and sequential hydrogen adsorption at activated Ov-neighboring sites, leading to significantly enhanced HER kinetics. Meanwhile, Y doping offers stabilization effect on Ov by its stronger Y─O bonding over Ce─O, which endows the catalyst with excellent stability. The Y,Co-CeO2 electrocatalyst exhibits an ultra-low HER overpotential (27 mV at 10 mA cm-2) and Tafel slope (48 mV dec-1), outperforming the benchmark Pt electrocatalyst. Moreover, the anion exchange membrane water electrolyzer incorporated with Y,Co-CeO2 achieves excellent stability of 500 h under 600 mA cm-2. This synergistic lattice strain and oxygen vacancy stabilization strategy sheds new light on the rational development of efficient and stable oxide-based HER electrocatalysts.

Size Effect of Cu Nanoparticles in Cu/g-C3N4 Composites on Properties for Highly Efficient Photocatalytic Reduction of CO2 to Methanol.

The main goal of this work is to develop cheap photocatalysts for the efficient photocatalytic reduction of CO2 to methanol with water. A series of composites of Cu/g-C3N4 were prepared via a solvothermal method. Copper nanoparticle (Cu NP) size in Cu/g-C3N4 can be easily controlled by adjusting the synthesis temperature. The Cu/g-C3N4 material with the proper size of Cu NP (CuCN-100) had the best photocatalytic property (675 µmol·g-1·h-1) in reducing the amount of CO2 to methanol at room temperature under normal pressure. The particle size of Cu NPs is the key factor to improve the catalytic activity and stability because of the improved transfer and separation of photogenerated charges with the small Cu NPs. Although the sample with large Cu NPs (CuCN-200) initially gave a better activity than that of CuCN-100 due to the formation of double heterojunction, its activity was thoroughly lost after two runs resulting from the continuous photocorrosion. This work provides a valuable insight for preparing efficient semiconductor-metal photocatalysts.

Study on the Adsorption Properties of Oxalic Acid-Modified Cordierite Honeycomb Ceramics for Neutral Red Dyes.

Removal of organic dyes from water by monolithic adsorbents is considered as an efficient and no-secondary pollution method. Herein, for the first time cordierite honeycomb ceramics (COR) treated with oxalic acid (CORA) were synthesized. This CORA exhibits outstanding removal efficiency toward the azo neutral red dyes (NR) from water. After optimizing the reaction conditions, the highest adsorption capacity of 7.35 mg·g-1 and a removal rate of 98.89% could be achieved within 300 min. Furthermore, investigation of the adsorption kinetics indicated this adsorption process could be described as a pseudo-second-order kinetic model with k 2 and q e of 0.0114 g·mg-1·min-1 and 6.94 mg·g-1, respectively. According to the fitting calculation, the adsorption isotherm could also be described as the Freundlich isotherm model. The removal efficiency could be maintained above 50% after 4 cycles, negating the need for toxic organic solvent extraction, offering a method for bringing the technology one step closer to industrial application and giving CORA promising potential in practical water treatment.

Spatiotemporal variation in vegetation phenology and its response to climate change in marshes of Sanjiang Plain, China.

Sanjiang Plain is the largest marsh distribution area of China, and marshes in this region significantly affect regional carbon cycle and biodiversity protection. The vegetation phenology of marsh significantly affects the energy exchange and carbon cycle in that region. Under the influence of global climatic change, identifying the changes in phenology and their responses to climatic variation in marshes of Sanjiang Plain is essential for predicting the carbon stocks of marsh ecosystem in that region. Using climate and NDVI data, this paper analyzed the spatiotemporal variations in the start (SOS), end (EOS), and length (LOS) of vegetation growing season and explored the impacts of climatic variation on vegetation phenology in marshes of Sanjiang Plain. Results showed that the SOS advanced by 0.30 days/a, and EOS delayed by 0.23 days/a, causing LOS to increase significantly (p < .05) by 0.53 days/a over marshes of Sanjiang Plain. Spatially, the large SOS advance and EOS delay resulted in an obvious increasing trend for LOS in northern Sanjiang Plain. The rise of spring and winter temperatures advanced the SOS and increased the LOS, and the rise in temperature in autumn delayed the EOS in marshes of Sanjiang Plain. Our findings highlight the necessity of considering seasonal climatic conditions in simulating marsh vegetation phenology and indicate that the different influences of climatic variation on marsh vegetation phenology in different regions should be fully considered to assess the marsh ecosystem response to climatic change in Sanjiang Plain.

Variation in Vegetation Phenology and Its Response to Climate Change in Marshes of Inner Mongolian.

Inner Mongolia has a large area of marsh wetland in China, and the marsh in this region is important for maintaining ecological balance. Understanding variations in vegetation phenology of marsh ecosystems and their responses to climatic change is crucial for vegetation conservation of marsh wetlands in Inner Mongolia. Using the climate and NDVI data during 2001-2020, we explored the spatiotemporal changes in the start (SOS), end (EOS), and length (LOS) of vegetation growing season and analyzed the effects of climate change on vegetation phenology in the Inner Mongolia marshes. Results showed that SOS significantly (p < 0.05) advanced by 0.50 days/year, EOS significantly delayed by 0.38 days/year, and thus LOS considerably increased by 0.88 days/year during 2001-2020 in marshes of Inner Mongolia. Warming temperatures in winter and spring could significantly (p < 0.05) advance the SOS, and increased summer and autumn temperatures could delay EOS in Inner Mongolia marshes. We found for the first time that daytime maximum temperature (Tmax) and night minimum temperature (Tmin) had asymmetric effects on marsh vegetation phenology. Increasing Tmax had a stronger advancing effect on SOS than increasing Tmin from December to April. The increase of Tmin in August could obviously delayed EOS, while increasing Tmax in August had no significant effect on EOS. This study highlights that the asymmetric influences of nighttime and daytime temperatures should be taken into account in simulating marsh vegetation phenology in temperate arid and semi-arid regions worldwide, particularly in the context of global asymmetric diurnal warming.

Effect of spaceflight on the phenotype and proteome of Escherichia coli.

Microbial safety has become a research hotspot with the development of manned space technology. Escherichia coli is a conditional pathogen that can cause infectious diseases. Therefore, it is necessary to study the influence of the space environment on E. coli. Phenotypic experiments including growth curves, morphology, and environmental resistance experiment were used to study the phenotypic changes of E. coli after exposure to the space environment for 12 days carried by the "SJ-10" satellite. Tandem mass tag was used to assess the proteome change of E. coli. We found that the survival rate of E. coli in the spaceflight group was decreased when cultivated in acidic and high-salt environments. Proteomic analysis identified 72 downregulated proteins involved in chemotaxis, intracellular pH elevation, glycolate catabolic process, and glutamate metabolic process in the spaceflight group. Meanwhile, only one protein mtr that was involved in the uptake of tryptophan in E. coli was upregulated in the spaceflight group. Our research showed that proteomics results can explain phenotypic results, which demonstrated the successful application of proteomics in mechanism research. Our data provide a comprehensive resource for understanding the effect of the space environment on E. coli.

Spatiotemporal Change of Net Primary Productivity and Its Response to Climate Change in Temperate Grasslands of China.

The temperate grasslands in China play a vital part in regulating regional carbon cycle and climate change. Net primary productivity (NPP) is a crucial index that reflects ecological function of plants and the carbon sequestration capacity of grassland ecosystem. Climate change can affect NPP by changing vegetation growth, but the effects of climate change on the NPP of China's temperate grasslands remain unclear. Based on MODIS data and monthly climate data during 2000-2020, this study explored the spatiotemporal changes in grassland NPP and its response to climate change in temperate grasslands of China. We found that the annual NPP over the entire China's temperate grasslands increased significantly by 4.0 gC/m2/year from 2000 to 2020. The annual NPP showed increasing trends for all the different grassland vegetation types, with the smallest increase for temperate desert steppe (2.2 gC/m2/year) and the largest increase for temperate meadow (5.4 gC/m2/year). The correlation results showed that increased annual precipitation had a positive relationship with the NPP of temperate grasslands. Increased summer and autumn precipitation could increase grassland NPP, particularly for the temperate meadow. With regard to the effects of temperatures, increased temperature, particularly the summer maximum temperature, could decrease annual NPP. However, increased spring minimum temperature could increase the NPP of temperate desert steppe. In addition, this study found, for the first time, an asymmetric relationship between summer nighttime and daytime warming and the NPP of temperate meadow. Specifically, nighttime warming can increase NPP, while daytime warming can reduce NPP in temperate meadow. Our results highlight the importance of including seasonal climate conditions in assessing the vegetation productivity for different grassland types of temperate grasslands and predicting the influences of future climate change on temperate grassland ecosystems.