Kinetic-Thermodynamic Promotion Engineering toward High-Density Hierarchical and Zn-Doping Activity-Enhancing ZnNiO@CF for High-Capacity Desalination

Despite the promising potential of transition metal oxides(TMOs)as capacitive deionization(CDI)electrodes,the actual capacity of TMOs electrodes for sodium storage is significantly lower than the theoretical capacity,posing a major obstacle.Herein,we prepared the kinetically favorable Zn_(x)Ni_(1−x)O electrode in situ growth on carbon felt(Zn_(x)Ni_(1−x)O@CF)through constraining the rate of OH^(−)generation in the hydrothermal method.Zn_(x)Ni_(1−x)O@CF exhibited a high-density hierarchical nanosheet structure with three-dimensional open pores,benefitting the ion transport/electron transfer.And tuning the moderate amount of redox-inert Zn-doping can enhance surface electroactive sites,actual activity of redox-active Ni species,and lower adsorption energy,promoting the adsorption kinetic and thermodynamic of the Zn_(0.2)Ni_(0.8)O@CF.Benefitting from the kinetic-thermodynamic facilitation mechanism,Zn_(0.2)Ni_(0.8)O@CF achieved ultrahigh desalination capacity(128.9 mgNaCl g^(-1)),ultra-low energy consumption(0.164 kW h kgNaCl^(-1)),high salt removal rate(1.21 mgNaCl g^(-1) min^(-1)),and good cyclability.The thermodynamic facilitation and Na^(+)intercalation mechanism of Zn_(0.2)Ni_(0.8)O@CF are identified by the density functional theory calculations and electrochemical quartz crystal microbalance with dissipation monitoring,respectively.This research provides new insights into controlling electrochemically favorable morphology and demonstrates that Zn-doping,which is redox-inert,is essential for enhancing the electrochemical performance of CDI electrodes.

碱金属阳离子对铁卟啉电催化CO_(2)还原的影响

电催化CO_(2)还原反应(CO_(2)RR)可以有效地将温室气体转化为燃料或高附加值的化学品,从而缓解目前人类所面临的环境问题和能源危机,其中开发高效的电催化剂是至关重要的环节.近年来,研究者设计了多种高效的过渡金属配合物(包括Mn,Fe,Co,Ni和Cu)用作CO_(2)RR分子电催化剂,并研究了其中的构效关系,例如,在分子内修饰质子给体取代基或电荷取代基可以显著提高CO_(2)RR的催化效率.而电催化CO_(2)RR的实际应用要在含有碱金属阳离子(例如,Na^(+)和K^(+))的电解质水溶液中进行,但在已有报道中,很少有关于碱金属阳离子对CO_(2)RR的影响.在众多的分子催化剂中,铁卟啉可以以较高的催化活性和选择性实现CO_(2)到CO的转化.重要的是,卟啉环的刚性结构、稳定的配位环境及其骨架上官能团的易于修饰性成为研究CO_(2)RR的构效关系的理想分子模型.基于以上考虑,本文以铁卟啉配合物为分子模型,研究了碱金属阳离子Na^(+)和K^(+)对电催化CO_(2)RR的影响.首先,本文合成了简单的A4型铁卟啉化合物四-(3,4,5-三甲氧基苯基)-铁卟啉(FeP).并采用核磁共振、质谱分析、单晶衍射等表征手段对化合物进行了表征,在含有电解质的DMF溶液中测试其电催化CO_(2)还原性能.实验结果表明,FeP可以实现高效的电催化CO_(2)还原,催化电流随FeP的浓度呈线性增加,说明催化反应速率与催化剂浓度呈一级反应速率关系.较长时间的恒电压电解实验以及电解前后化合物的紫外-可见光谱证实了FeP的稳定性.通过气相色谱对产物进行分析,CO为主要产物,法拉第效率为95%.以上结果均表明,FeP是一个优良的分子催化剂.在此基础上,本文还发现加入Na^(+)和K^(+)均可以显著提升催化活性,而K^(+)的加入使催化电流的提升更加显著,这可能是由于K^(+)在溶液中的迁移速度比Na^(+)更快.基于此实验现象,本文通过在FeP的第二配位层修饰1-氨-18-冠-6-醚官能团(^(N)18C6),合成了^(N)18C6-FeP化合物.结果表明,由于^(N)18C6与Na^(+)/K^(+)之间的配位作用,使得^(N)18C6-FeP比FeP具有更好的电催化CO_(2)RR活性.研究表明,催化活性的提升归因于碱金属阳离子能够通过静电相互作用稳定Fe-CO_(2)中间体.1H NMR谱证实了^(N)18C6基团的确能够螯合碱金属阳离子.本文研究证明了碱金属阳离子对改善电催化CO_(2)RR的积极作用,对于进一步深入了解CO_(2)RR催化反应机理和未来合理的设计高效催化剂也都具有重要意义.

胍基铁卟啉显著提高了水溶液中电催化二氧化碳还原的活性和选择性

电催化CO_(2)还原反应(CO_(2)RR)可以制造燃料和增值化学品,为使用化石燃料带来的相关问题提供了理想的解决策略,因此,开发具有高效率、高选择性的CO_(2)RR电催化剂引起了人们的广泛关注.最近的研究表明,第一过渡金属配合物包括Mn,Fe,Co,Ni和Cu,均可作为CO_(2)RR电催化剂.在众多配合物中,铁卟啉化合物是研究结构-功能关系的理想模型复合物之一,因为卟啉大环化合物可以为中心金属离子提供强大而稳定的配位环境,并且可以通过引入各种官能团进行系统修饰,同时也因其在非水溶液中可以高效地催化CO_(2)转化为CO的而备受关注.然而,与非水溶液体系不同,铁卟啉在水溶液中CO_(2)RR表现出较差或中等的选择性,其原因在于当使用水作为反应介质时,竞争性析氢反应会变得严重.众所周知,使用水作为电催化反应溶剂,不仅绿色环保,而且可以充分提供二氧化碳还原过程中所需的质子.因此,开发水溶剂中铁卟啉CO_(2)RR电催化剂,使其在水溶液中表现出高活性高选择性具有重要的现实意义.本文设计并合成了带有胍基的铁卟啉化合物1以及简单的A4型铁卟啉化合物2,利用核磁共振、质谱分析等手段对化合物进行了表征,研究了两种化合物在非水溶液(均相电催化)和水溶液(多相电催化)中对CO_(2)RR的电催化性质.在乙腈溶液中,铁卟啉1及铁卟啉2均能有效地将CO_(2)转化为CO,转化频率表现为1(3.9×10^(5)s^(-1))比2(1.7×10^(4)s^(-1))大一个数量级,表明了胍基在提高电催化CO_(2)RR活性方面的关键作用.更重要的是,胍基具有生物相容性,可以在pH≤7的水溶液中被质子化,因此将化合物负载在碳纳米管(CNTs)上,研究其在0.1 mol L^(-1)KHCO_(3)水溶液中催化CO_(2)RR活性,结果表明,1/CNT显示出非常高的电催化CO_(2)-CO转化选择性,法拉第效率为96%,而2/CNT仅为65%,同时1/CNT在水溶液中长时间电解的CO_(2)RR电催化效率仍然优于2/CNT.综上,本文研究结果表明胍基对提高铁卟啉CO_(2)RR电催化的活性和选择性具有重要意义.

Study on Extraction and Antioxidant Activity of Flavonoids from Dendranthema indicum

[Objectives] To determine the optimal extraction technology of flavonoids in Dendranthema indicum,and analyze the antioxidant activity of total flavonoids in D. indicum. [Methods]D. indicum was used as raw material to extract the total flavonoids by water extraction,alcohol extraction,freeze-thaw,microwave assisted extraction and ultrasonic extraction. [Results]Microwave assisted extraction had the highest extraction rate. Therefore,the microwave assisted extraction was selected as the main method,the ethanol aqueous solution was used as the solvent,and the single factor experiment was carried out with microwave power,ethanol volume fraction,solid-to-liquid ratio and microwave time as the variables. The optimal extraction process of flavonoids was microwave power 400 W,solid-to-liquid ratio 1 ∶ 30,extraction time60 s,ethanol volume fraction 70%,under this condition,the extraction yield was 10. 65 mg/g. The antioxidant activity of flavonoids in D. indicum was determined. The results showed that the highest scavenging rate of DPPH·free radicals was 47. 89%,and the highest scavenging rate of hydroxyl radicals was 98. 00%. [Conclusions]The flavonoids in D. indicum have excellent antioxidant activity. This study is expected to provide a basis for further development of D. indicum products.

An efficient approach for the treatment of radioactive waste perfluoropolyether lubricants via a synergistic effect of thermal catalysis and immobilization

Perfluoropolyether(PFPE)lubricants are a kind of high-molecular polymer with many excellent properties.However,the use of PFPEs in the nuclear industry can lead to partial decomposition and carrying radionuclides,resulting in a large amount of radioactive waste PFPE lubricants annually.Moreover,radioactive waste PFPE lubricants are difficult to be effectively treated due to their high stability,the risk of possible leakage of radionuclides,and hypertoxic fluorine-containing by-products.In this study,without any precedent,a strategy of Mn O_(2)-catalyzed decomposition and Na_(2)CO_(3)-immobilized conversion was proposed for PFPE lubricant decomposition and fluorine immobilization simultaneously based on the Lewis acid-base and oxygen vacancies concept.A high fluorine conversion efficiency of 95.4%was achieved.Meanwhile,the mechanism of decomposition suggested that Mn O_(2)mainly provided Lewis acid sites and attacked the(basic)fluorine or oxygen atoms in PFPE molecules.The decomposition of PFPE chains was proceed down and volatile fluorine-containing gas was released by partial electron transfer,intramolecular disproportionation reaction,and unzipping fashion.Subsequently,gas by-products could be further oxidized and then immobilized into fluoride salts by carbonate solid absorbents.Overall,this study provides a simple,safe,and potentially practical strategy for the harmless conversion of refractory fluorinated organic wastes,especially perfluoropolymers.

Effects of scenario-based carbon pricing policies on China's dual climate change mitigation goals: Does policy design matter?

Although the carbon pricing policy is a critical driving factor that will help China achieve economic growth,energy transition,and dual climate change mitigation goals,the kind of carbon pricing policy that will complement the country's current development situation remains controversial.We apply the World Induced Technical Change Hybrid(WITCH)model to explore the heterogeneity and synergy of different carbon pricing policies,and the results indicate that it will be challenging to achieve carbon neutrality before 2060.The study find that the combined policy-a mix of carbon tax and carbon market policies--has the optimal emission reduction effect but comes with the highest economic cost,proving to be unsuitable in the long run.The carbon tax policy is an important transitional means to assist in emission reduction,which can serve as an important supplement to carbon market policy and be phased out after the market mechanism matures.

Electropolymerization of cobalt porphyrins and corroles for the oxygen evolution reaction

Developing large-scale electrocatalysts using molecular complexes for the oxygen evolution reaction(OER)is of great importance. Herein, four cobalt porphyrins and corroles are deposited on electrode substrates using a simple and fast electropolymerization method. Our results showed that Co-1-P@CC, formed by electropolymerizing Co tetrakis(p-N-pyrrolylphenyl)porphyrin(Co-1-P) on carbon cloth(CC), is the most active OER catalyst in the examined Co porphyrins and corroles in alkaline aqueous solutions by displaying an onset overpotential of 380 m V. Long-term electrolysis tests confirmed the stability of these electropolymerized films by functioning as OER electrocatalysts.

Preparation of Ce-TiO_2/carbon aerogel electrode and its performance in degradation of 4-chlorophenol

Ce-TiO2/CA（carbon aerogel） electrode was prepared by sol impregnation approach. The XRD（X-ray diffraction） and Raman spectra reveal that the TiO2 is anatase. The UV-vis diffuse reflectance spectra show that the optical absorption edge for Ce-TiO_2/CA is red-shifted to 535 nm compared with TiO_2/CA. Under visible light irradiation, the photocurrent density increment on Ce-TiO_2/CA is 75 times that on Ce-TiO_2/FTO（fluorine-doped tin oxide）. The electrochemical impedance spectroscopy reveals that the conductivity of CeTiO_2/CA is much better than the Ce-TiO_2/FTO. Furthermore, the Ce-TiO_2/CA can be used to the highest electrosorptive photodegradation for 4-chlorophenol wastewater degradation, which is ascribed predominantly to the efficient reduction of electron-hole pair recombination in the photocatalysts.

Long-term mercury variations in tree rings of the permafrost forest,northeastern China

Permafrost is a potential mercury(Hg)pool released by thawing,which can raise the risk of Hg pollution under global warming.Tree rings are useful archives of environment-specific Hg exposure over long periods.We determined Hg concentrations in tree rings of two dominant tree species(Larix gmelinii Rupr.and Pinus sylvestris var.mongolica)at permafrost sites in northeastern China.The biweighted mean Hg concentrations ranged from 0.36 to 3.96 ng g^(-1) from 1840 to 2014.The tree-ring width had no significant influence on the Hg concentration.Larch Hg increased slightly before the 1970 s and peaked in the 1990 s.However,the pine Hg concentration increased continuously until the 1930 s,decreased rapidly until the 1970 s,then rose to a peak in the late 1980 s.The change of Hg concentrations in larch and pine revealed a time offset of 4 to 5 years,which implied possibly high mobility of Hg in pine tree rings.Higher Hg concentrations from 1920 to 1960 and subsequent decreases in isolated permafrost forests revealed the local geographical Hg cycling history.Lower Hg concentrations and faster increases in larch suggest the role of additional winter Hg loading for the evergreen pine and species-specific differences in root absorption in response to melting permafrost.Our results highlight possible geographical impacts on tree-ring Hg records,improve understanding of Hg cycles in permafrost forest,and suggest a need to sample additional species in a range of permafrost environments.

Effects of water quality on the coagulation performances of humic acids irradiated with UV light

The presence of humic acid in drinking water treatment has received significant attention in recent years because of its adverse effects on the removal of many pollutants in coagulation. In this paper, the effects of water quality including pH, turbidity, alkalinity, and hardness on the removal of humic acid were investigated in a UV light hybridized coagulation process. Our results suggested that UV light radiation could effectively improve the removal rate of humic acid in coagulation under both neutral and basic conditions, and the variations of the selected water quality parameters had little adverse effect on the function of UV light. After UV light radiation, the removal rate of the nitro-humic acid （NHA） increased from 20% to 60% in coagulation, and increased further to 75% and 85% for the raw waters with 10.0 NTU kaolin and 100mg.L-1 hardness, respectively. In addition to NHA, the removal rates of the humic acid extracted from peat coal （PHA） and the humic acid provided by Japan metals and chemicals company （JHA） in coagulation were also improved, both in the range of 80%-90% after undergoing UV light radiation. By changing the radiation location from prior to coagulation to the flocculation process, similar experimental results were obtained. The formation of positive charged sites after UV light radiation was considered to be the primary factor that led to an enhanced removal of the humic acid in coagulation.

Quantitative Analysis and Prediction of China's Natural Gas Consumption in Different Sectors Based on Bayesian Network

In view of the heterogeneity of natural gas consumption in different sectors in China,this paper utilizes Bayesian network(BN)to study the driving factors of natural gas consumption in power generation,chemical and industrial fuel sectors.Combined with Bayesian model averaging(BMA)and scenario analysis,the gas consumption of the three sectors is predicted.The results show that the expansion of urbanization will promote the gas consumption of power generation.The optimization of industrial structure and the increase of industrial gas consumption will enhance the gas consumption of chemical sector.The decrease of energy intensity and the increase of gas consumption for power generation will promote the gas consumption of industrial fuel.Moreover,the direct influencing factors of gas price are urbanization,energy structure and energy intensity.The direct influencing factors of environmental governance intensity are gas price,urbanization,industrial structure,energy intensity and energy structure.In 2025,under the high development scenario,China’s gas consumption for power generation,chemical and industrial fuel sectors will be 66.034,36.552 and 109.414 billion cubic meters respectively.From 2021 to 2025,the average annual growth rates of gas consumption of the three sectors will be 4.82%,2.18%and 4.43%respectively.

Tuning Electronic Structures of Covalent Co Porphyrin Polymers for Electrocatalytic CO_(2) Reduction in Aqueous Solutions

Improving the selectivity of the electrocatalytic CO_(2) reduction reaction(CO_(2)RR)over hydrogen evolution in aqueous solutions is required but challenging because the two reactions occur at close thermodynamic potentials and compete with each other.Herein,we report on the selective CO_(2)RR in aqueous solutions utilizing covalent Co porphyrin polymers with fine-tuned electronic structures.

Bioinspired iron porphyrins with appended poly-pyridine/amine units for boosted electrocatalytic CO_(2) reduction reaction

Developing highly efficient electrocatalysts for the CO_(2) reduction reaction(CO_(2)RR)has attracted increasing interest in the past decade.Herein,we report on the design and synthesis of Fe porphyrin 1 with an appended N,N-di(2-picolyl)ethylenediamine(DPEN)unit that boosts electrocatalytic activity for CO_(2)-to-CO conversion in acetonitrile with water as the proton source.By mimicking carbon monoxide dehydrogenase(CODH),1 has poly-pyridine/amine units located at the active site to form hydrogen-bonded water-containing networks that enable fast proton transfer.The protonated and positively charged DPEN unit can also stabilize CO_(2) reduction intermediates through electrostatic and hydrogen-bonding interactions.These factors make 1 a highly active electrocatalyst for the CO_(2)RR by achieving a TOFmax of 5.0​×​10^(4)​s^(−1) with water providing the protons.These critical roles of the DPEN unit in the CO_(2)RR are further supported by theoretical studies.This work is significant to highlight the benefits of using molecular catalysts to elucidate structural effects.