Defects‑Rich Heterostructures Trigger Strong Polarization Coupling in Sulfides/Carbon Composites with Robust Electromagnetic Wave Absorption

Defects-rich heterointerfaces integrated with adjustable crystalline phases and atom vacancies,as well as veiled dielectric-responsive character,are instrumental in electromagnetic dissipation.Conventional methods,however,constrain their delicate constructions.Herein,an innovative alternative is proposed:carrageenan-assistant cations-regulated(CACR)strategy,which induces a series of sulfides nanoparticles rooted in situ on the surface of carbon matrix.This unique configuration originates from strategic vacancy formation energy of sulfides and strong sulfides-carbon support interaction,benefiting the delicate construction of defects-rich heterostructures in M_(x)S_(y)/carbon composites(M-CAs).Impressively,these generated sulfur vacancies are firstly found to strengthen electron accumulation/consumption ability at heterointerfaces and,simultaneously,induct local asymmetry of electronic structure to evoke large dipole moment,ultimately leading to polarization coupling,i.e.,defect-type interfacial polarization.Such“Janus effect”(Janus effect means versatility,as in the Greek two-headed Janus)of interfacial sulfur vacancies is intuitively confirmed by both theoretical and experimental investigations for the first time.Consequently,the sulfur vacancies-rich heterostructured Co/Ni-CAs displays broad absorption bandwidth of 6.76 GHz at only 1.8 mm,compared to sulfur vacancies-free CAs without any dielectric response.Harnessing defects-rich heterostructures,this one-pot CACR strategy may steer the design and development of advanced nanomaterials,boosting functionality across diverse application domains beyond electromagnetic response.

甘南卓尼(co-ne)历史文化研究综述

卓尼不仅在历史上受到历代中央王朝的关注,而且也是近当代人类学、社会学家们从事学术研究的热点地区,产生了相关方面的诸多研究成果。文章通过对相关论文的盘点,分析了卓尼地域文化研究的现状并展望了未来研究趋势。

试论羌族的生态伦理观念

关爱生命,珍惜自然是人类生存的自然法则。羌族传统的生态伦理观念,体现了人类生存的智慧,也是人们注重对自然的利用和保护,尤其是万物有灵的观念,彰显了羌族与自然平等相处,相互依存的密切关系。羌族在历史的发展过程中,虽居住的地域不同,传统的生态伦理观念却相通,对人们的生产生活实践、处理人与自然的关系和传统文化的继承发挥了举足轻重的作用,文章就羌族的生态伦理观念简要作了概述。

西北民族走廊上的族际亲缘关系研究--兼论其对铸牢中华民族共同体意识的启示

本文以西北民族走廊上的唐、孔两姓为个案,对其“跨”民族的族际亲缘关系进行了分析,表现了中国家族文化中以“和”为核、强调个体忠孝于家庭、家族、国家的伦理价值观念,认为这些“优秀传统文化因子”对于传承“个人-家庭-家族-国家”这一充满差序格局色彩的“文化基因”发挥着筑基树本的作用,成为培育“各民族亲如一家”认同的重要力量,能够为铸牢中华民族共同体意识增益裨助。

卓尼版《大藏经》及其国内外的影响

历史上,藏传佛教寺院不仅具备弘扬佛法的功能,还肩负了传播文化的功能。建于元代的禅定寺,在甘南卓尼历代杨土司的苦心经营下,一度成为安多地区宗教和文化中心,尤其该寺刊刻《大藏经》后,卓尼版《大藏经》举世瞩目,不仅在藏传佛教发展史上产生了深远的影响,在国内外学术界也产生了广泛的影响。文章依据藏汉文文献资料,对卓尼版《大藏经》及其国内外的影响作了论述。

Highly dispersed few-layer MoS_2 nanosheets on S, N co-doped carbon for electrocatalytic H_2 production

Ultrathin small MoS2nanosheets exhibit a higher electrocatalytic activity for the hydrogen evolution reaction.However,strong interactions between MoS2layers may result in aggregation;together with the low conductivity of MoS2,this may lower its electrocatalytic activity.In this paper we present a method that we developed to directly produce solid S,N co‐doped carbon(SNC)with a graphite structure and multiple surface groups through a hydrothermal route.When Na2MoO4was added to the reaction,polymolybdate could be anchored into the carbon materials via a chemical interaction that helps polymolybdate disperse uniformly into the SNC.After a high temperature treatment,polymolybdate transformed into MoS2at800°C for6h in a N2atmosphere at a heating rate of5°C/min,owing to S2?being released from the SNC during the treatment(denoted as MoS2/SNC‐800‐6h).The SNC effectively prevents MoS2from aggregating into large particles,and we successfully prepared highly dispersed MoS2in the SNC matrix.Electrochemical characterizations indicate that MoS2/SNC‐900‐12h exhibits a low onset potential of115mV and a low overpotential of237mV at a current density of10mA/cm2.Furthermore,MoS2/SNC‐900‐12h also had an excellent stability with only^2.6%decay at a current density of10mA/cm2after5000test cycles.

A novel electro-Fenton hybrid system for enhancing the interception of volatile organic compounds in membrane distillation desalination

Membrane distillation(MD)is a promising alternative desalination technology,but the hydrophobic membrane cannot intercept volatile organic compounds(VOCs),resulting in aggravation in the quality of permeate.In term of this,electro-Fenton(EF)was coupled with sweeping gas membrane distillation(SGMD)in a more efficient way to construct an advanced oxidation barrier at the gas-liquid interface,so that the VOCs could be trapped in this layer to guarantee the water quality of the distillate.During the so-called EF-MD process,an interfacial interception barrier containing hydroxyl radical formed on the hydrophobic membrane surface.It contributed to the high phenol rejection of 90.2% with the permeate phenol concentration lower than 1.50 mg/L.Effective interceptions can be achieved in a wide temperature range,even though the permeate flux of phenol was also intensified.The EF-MD system was robust to high salinity and could electrochemically regenerate ferrous ions,which endowed the long-term stability of the system.This novel EF-MD configuration proposed a valuable strategy to intercept VOCs in MD and will broaden the application of MD in hypersaline wastewater treatment.

Tailoring color emissions from N-doped graphene quantum dots for bioimaging applications

Unlike inorganic quantum dots,fluorescent graphene quantum dots(GQDs)display excitation-dependent multiple color emission.In this study,we report N-doped GQDs(N-GQDs)with tailored single color emission by tuning p-conjugation degree,which is comparable to the inorganic quantum dot.Starting from citric acid and diethylenetriamine,as prepared N-GQDs display blue,green,and yellow light emission by changing the reaction solvent from water,dimethylformamide(DMF),and solvent free.The X-ray photoelectron spectroscopy,ultraviolet-visible spectra results clearly show the N-GQDs with blue emission(N-GQDs-B)have relatively short effective conjugation length and more carboxyl group because H_(2)O is a polar protic solvent,which tends to donate proton to the reagent to depress the H_(2)O elimination reaction.On the other hand,the polar aprotic solvent(DMF)cannot donate hydrogen,the elimination of H_(2)O is promoted and more nitrogen units enter GQD framework.With the increase of effective p-conjugation length and N content,the emission band of N-GQDS red-shifts to green and yellow.We also demonstrate that N-GQDs could be a potential great biomarker for fluorescent bioimaging.

Removal of Pb(Ⅱ) from aqueous solution by hydrous manganese dioxide:Adsorption behavior and mechanism

Hydrous manganese dioxide （HMO） synthesized by redox of potassium permanganate and hydrogen peroxide was used as an adsorbent for Pb（Ⅱ） removal.The specific surface area,pore volume and BJH pore diameter of the HMO were 79.31m2/g,0.07cm3/g and 3.38 nm,respectively.The adsorption equilibrium at 298K could be well described by the Langmuir isotherm equation with q max value of 352.55mg/g.The negative values of G and the positive values of H and S indicated the adsorption process was spontaneous and endothermic.The pseudo second-order equation could best fit the adsorption data.The value of the calculated activation energy for Pb（Ⅱ） adsorption onto the HMO was 38.23 kJ/mol.The uptake of Pb（Ⅱ） by HMO was correlated with increasing surface hydroxyl group content and the main adsorbed speciation was PbOH＋.The final chemical state of Pb（Ⅱ） on the surface of HMO was similar to PbO.HMO was a promising candidate for Pb（Ⅱ） removal from aqueous solution.

基于聚苯胺/二氧化钛/天然纤维素的污水自清洁太阳能水蒸发装置

水体污染是当前造成淡水短缺的主要原因之一.利用太阳能水蒸发装置从海水或污水中生产淡水是一种简单有效且节能的解决淡水危机的方式,引起了广泛的关注.然而,污染物的共同蒸发或沉积可能会降低水蒸发过程中的效率和淡水质量.本文基于天然木质纤维素(NCF)、聚苯胺(PANI)和二氧化钛(TiO_(2))开发了自清洁太阳能水蒸发器,其具有宽吸收、亲水性强、导热系数低等优点.通过在聚合物溶液中加入木质纤维素,聚苯胺纳米纤维在NCF表面聚合形成介孔网络.P25 TiO_(2)纳米颗粒作为光催化剂分散到上述反应液中,通过简单的过滤形成PANI/TiO_(2)/NCF复合材料.由于太阳水蒸发器装置中PANI的光热效应与TiO_(2)纳米颗粒的光催化降解的协同作用,水蒸发速率可达2.36 kg m^(-2)h^(-1)(1个太阳光照射下),且可有效降解污染物(100 ppm四环素).更重要的是,在工作10 h后,该太阳能水蒸发器装置仍然保持稳定的水蒸发速率,且没有污染物的积聚.光催化和光热效应相结合的双功能太阳能水蒸发装置在有机污染物水中具有自清洁作用,具有很大的应用潜力.

研发双层结构的碳基水凝胶材料提高太阳能水蒸发效率

太阳能水蒸发对于解决净水危机潜力无限.随着研究的深入,研发高效光热转换材料和合理的材料结构设计均可以提高光热蒸发速率.因此,我们设计合成了一种双层碳基水凝胶复合材料.在一个太阳光照条件下,其最大蒸发速率可达2.19 kg m^(−2)h^(−1),光热转换效率可达93.7%.同时,该复合材料展现了优异的海水淡化性能及良好的稳定性,扩展了实际应用范围.除此之外,其可控规模化及便携性可以自如面对多种复杂的应用环境,成本低廉可以使其大规模应用于经济落后地区,为复合结构水凝胶蒸发器的生产提供了可供参考的设计思路和策略.

具有优越电催化析氢性能的超小碳负载FeRu合金

电化学水分解是将可再生能源产生的间歇性电能转化为高纯度氢气的一种极具前景的绿色能源技术.目前,高效制氢催化剂主要由贵金属及其化合物组成,而贵金属的高成本及稀缺性,限制了其在大规模工业化制氢中的应用.因此,探索低成本,高电化学活性、高稳定性的电解水制氢催化剂至关重要.合金化材料以短程或长程有序结构存在,具有增强的电化学性能.因此,本文采用两步法制备超小碳负载FeRu合金纳米电催化剂并将其应用于电催化析氢反应.Fe_(0.05)Ru_(0.05)/XC-72双功能电催化剂粒径为2.1 nm,在碱性淡水和海水电解质中表现出优异的活性和耐久性.10 mA cm^(-2)时,在1 mol L^(-1)KOH、1 mol L^(-1)KOH+0.5 mol L^(-1)NaCl和1 mol L^(-1)KOH+海水中分别表现出13、15和18 mV的过电位.在1 mol L^(-1)KOH介质和-0.07 V(相比于可逆氢电极)条件下,Fe_(0.05)Ru_(0.05)/XC-72的析氢质量活性高达11.32Amg^(-1)_(noble metal).在1 mol L^(-1)KOH中,Fe_(0.05)Ru_(0.05)/XC-72电催化剂具有24 h以上的长期析氢反应(HER)稳定性.理论计算表明,引入Fe形成的FeRu合金可以诱导电子效应,使其对*H的吸附能力增强,进一步提高了HER性能.本工作对制备高电活性、高稳定性的钌基电催化剂具有重要的启发意义.

The critical factors of photocatalytic H2 production from seawater by using TiO_(2)as photocatalyst

The solar H_(2)generation directly from natural seawater is a sustainable way of green energy.However,it is limited by a low H_(2)generation rate even compared to fresh water.In this report,TiO_(2)is chosen as a model photocatalyst to disclose the critical factor to deteriorate the H_(2)generation rate from seawater.The simulated seawater(SSW),which is composed of eight ions(Na^(+),K^(+),Ca^(2+),Mg^(2+),Cl^(−),Br^(−),SO_(4)^(2−),and CO_(3)^(2−)),is investigated the effect of each ion on the H_(2)production.The results indicate that all ions have a negative effect at the same concentration as in the seawater except Br−.The CO_(3)^(2−)has the most serious deterioration,and the H_(2)production rate lowers near 40%even at[CO_(3)^(2−)]of 1.5 mmol·L^(−1).The H_(2)production rate can be recovered to 85%if the CO_(3)^(2−)is excluded from the SSW.To understand the reason,the zeta potential of the TiO_(2)treated with different ions aqueous solution reveals that the zeta potential decreases when it is treated with CO_(3)^(2−)and SO_(4)^(2−)due to they can adsorb on the surface of TiO_(2)nanoparticles.Fourier transform infrared(FTIR)and thermogravimetric analysis-mass spectroscopy(TGA-MS)further confirm that the adsorbed ion is mainly from CO_(3)^(2−).Since the pH of seawater is about 8.9 between pKa1(6.37)and pKa2(10.3)of H_(2)CO3,the CO_(3)^(2−)should exist in the form of HCO3−in the seawater.We proposed a simple method to remove the adsorbed HCO3−from the TiO_(2)surface by adjusting the pH below the pKa1.The results indicate that if a trace amount of HCl(adjusting pH~6.0)is added to the SSW,the H_(2)production rate can be recovered to 85%of that in pure water.

拉萨地区表观健康人群血清同型半胱氨酸水平分析和参考区间初步调查

目的分析拉萨地区不同民族表观健康人群的同型半胱氨酸(HCY)水平及其影响因素,初步建立参考区间。方法参考区间建立。分析西藏自治区人民医院2018年1月至12月820名表观健康体检人群血清HCY(μmol/L)水平,将全部人群按照民族、性别、年龄、季节分组,使用一般线性模型分析民族、性别、年龄、季节组别中血清HCY水平的差异。依据CLSI C28文件,使用Nested ANOVA和Z检验分析并确定临床应用中是否需要分组建立参考区间。结果经一般线性模型分析民族、年龄、性别对血清HCY存在显著影响,其中藏族HCY水平高于汉族(P<0.001);男性HCY水平高于女性(P<0.001);50岁以上人群HCY水平高于50岁以下人群(P=0.01),血清HCY水平在季节分布上差异无统计学意义(P=0.22)。Nested ANOVA和Z检验确定临床应用中需要依据民族和性别建立拉萨地区HCY的参考区间。其中,藏族男性的HCY参考区间为<22.41μmol/L,藏族女性HCY的参考区间为<18.41μmol/L。结论拉萨地区表观健康人群血清HCY水平在不同民族、性别、年龄人群中略有差异,本研究成功建立了西藏地区藏族男性和藏族女性的HCY参考区间。

TiO2 sensitized by red-, green-, blue-emissive carbon dots for enhanced H2 production

Carbon dots(Cdots)with a broad light absorption range could be a potential stable sensitizer for TiO2,which is an excellent ultraviolet(UV)response photocatalyst.Herein,we systematically investigated the different color emissive Cdots-sensitized TiO2 for H2 production.Firstly,all kinds of Cdots enhanced the photocatalytic properties of TiO2.All the Cdots-sensitized TiO2 exhibits visible light H2 production due to their absorption in the visible light region.The photocurrent and H2 production amount display strong dependence on the light absorption range of Cdots.The blue-emissive Cdots endow the weak H2 production rate due to its weak absorption in the visible light.The enhanced photocatalytic activities are mainly contributed to the strong light absorbance and high-efficient charge separation.The light absorption of green-and red-emissive Cdots is another main factor for the high catalytic activities besides charge separation.

Enhanced photocatalytic N2 fixation by promoting N2 adsorption with a co-catalyst

Photocatalytic N2 fixation involves a nitrogen reduction reaction on the surface of the photocatalyst to convert N2 into ammonia.Currently,the adsorption of N2 is the limiting step for the N2 reduction reaction on the surface of the catalyst.Based on the concept of photocatalytic water splitting,the photocatalytic efficiency can be greatly enhanced by introducing a co-catalyst.In this report,we proposed a new strategy,namely,the loading of a NiS co-catalyst on CdS nanorods for photocatalytic N2 fixation.Theoretical calculation results indicated that N2 was effectively adsorbed onto the NiS/CdS surface.Temperature programmed desorption studies confirmed that the N2 molecules preferred to adsorb onto the NiS/CdS surface.Linear sweep voltammetry results revealed that the overpotential of the N2 reduction reaction was reduced by loading NiS.Furthermore,transient photocurrent and electrochemical impedance spectroscopy indicated that the charge separation was enhanced by introducing NiS.Photocatalytic N2 fixation was carried out in the presence of the catalyst dispersed in water without any sacrificial agent.As a result,1.0 wt% NiS/CdS achieved an ammonia production rate of 2.8 and 1.7 mg L-1 for the first hour under full spectrum and visible light(λ>420 nm),respectively.The catalyst demonstrated apparent quantum efficiencies of 0.76%,0.39% and 0.09% at 420,475 and 520 nm,res pectively.This study provides a new method to promote the photocatalytic efficiency of N2 fixation.

Enhancing photocatalytic performance by constructing ultrafine TiO2 nanorods/g-C3N4 nanosheets heterojunction for water treatment

Photocatalysis is considered to be a clean, green and efficient method to purify water. In this report, we first developed a highly efficient ultrafine TiO2 nanorods/g-C3N4 nanosheets （TiO2 NR/CN NS） composites via a simple hydrothermal method. Tiny TiO2 nanorods （diameter： ～1.5 nm and length： ～8.3 nm） were first loaded in situ on the CN NS by adding graphitic carbon nitride （g-C3N4） to the reaction solution. The TiO2 NR/CN NS composites present high charge separation efficiency and broader light absorbance than P25 TiO2. Furthermore, we illustrate that the TiO2 NR/CN NS catalyst possesses high performance for the photocatalytic degradation of the common and stubborn pollutants in water, such as the rhodamine B （RhB） dye and phenol. Under visible light （λ 〉 420 nm） irradiation, the apparent rate of the TiO2 NR/CN NR is 172 and 41 times higher than that of the P25 TiO2 and TiO2 NR, respectively. Additionally, we speculated that the heterojunction formed between TiO2 NR and CN NS, which is the basis for the experiments we have designed and the corresponding results. We demonstrated that reactive oxidative species such as superoxide anion radical and holes play critical roles in the degradation, and the hydroxyl radical contributes nothing to the degradation.

Effect of defects on photocatalytic activity of rutile TiO2 nanorods

To further understand the effect of structural defects on the electrochemical and photocatalytic properties of TiO2, two synthetic approaches based on hydrothermal synthesis and post-synthetic chemical reduction to achieve oxygen defect- implantation were developed herein. These approaches led to the formation of TiO2 nanorods with uniformly distributed defects in either the bulk or on the surface, or the combination of both, in the formed TiO2 nanorods （NRs）. Both approaches utilize unique TiN nanoparticles as the reaction precursor. Electron microscopy and Brunauer-Emmett-Teller （BET） analyses indicate that all the studied samples exhibit similar morphology and similar specific surface areas. X-ray photoelectron spectroscopy （XPS） and electron paramagnetic resonance （EPR） data confirm the existence of oxygen defects （Vo）. The photocatalytic properties of TiO2 with different types of implanted Vo were evaluated based on photocatalytic H2 production. By optimizing the concentration of Vo among the TiO2 NRs subjected to different treatments, significantly higher photocatalytic activities than that of the stoichiometric TiO2 NRs was achieved. The incident photon-to-current efficiency （IPCE） data indicate that the enhanced photocatalytic activity arises mainly from defect-assisted charge separation, which implies that photo-generated electrons or holes can be captured by Vo and suppress the charge recombination process. The results show that the defective TiO2 obtained by combining the two approaches exhibits the greatest photocatalytic activity enhancement amon~ all the samples.

A metal-free carbon dots for wastewater treatment by visible light active photo-Fenton-like reaction in the broad pH range

Carbon dots(Cdots)has been proved to possess the catalytic decomposition of H_(2)O_(2) in the photocatalytic system.It is a potential photo-Fenton catalyst.Since multiple emissive Cdots have different light response range.There is rarely investigation on the performance of Cdots based photo-Fenton on the light wavelength.Herein,blue,green and red emissive carbon dots were synthesized from the different ratio of o-phenylenediamine and catechol by the solvothermal method.They exhibit different light adsorption range from UV to visible light.Furthermore,the photo-Fenton reactivity of Cdots was studied for catalyzing the decomposition of H_(2)O_(2) to generate free hydroxyl radicals and consequently applying for the removal of methyl blue.The results exhibit that Cdots with the broader light adsorption rang possess the stro nger catalytic activity for the photo-Fenton reaction.The H_(2)O_(2) decomposition rate of red emissive Cdots is 0.074 min^(-1),which is 2.64 and 1.46 times than the blue and green emissive Cdots,respectively.And the radical detection results confirm that the photo-Fenton happens in the reaction.In addition,the Cdots photo-Fenton can be carried out in the broad pH range from acidic to basic solution,which has a great potential to treat wastewater in the neutral system.

Surface hydrophobic modification enhanced catalytic performance of electrochemical nitrogen reduction reaction

Electrocatalytic nitrogen reduction reaction(NRR)is a sustainable approach for NH_(3)production with low energy consumption.However,competing hydrogen reduction reaction(HER)in aqueous solution results in low NH_(3)production and Faraday efficiency(FE).Here,MoS_(2)nanostructures with a hydrophobic surface are synthesized by alkyl thiols modification.Aerophilic and hydrophobic surface facilitates an efficient three-phase contact of N_(2),H_(2)O,and catalyst.Thus,localized concentrated N_(2)molecules can overcome the mass transfer limitation of N2 and depress the HER due to lowering the proton contacts.Although the active-sites decrease with the increase of the alkyl chain since the thiol may cover the active site,the optimized electrocatalyst achieves NH_(3)yield of 12.86×10^(-11)mol·cm^(-2)·s^(-1)at-0.25 V and 22.23%FE,which are 4.3 and 24 times higher than those of MoS2-CP electrocatalyst,respectively.The increased catalytic performance is attributed to the high N_(2)adsorption and depressed HER.