Au core-PtAu alloy shell nanowires for formic acid electrolysis

Inefficient electrocatalysts and high-power consumption are two thorny problems for electrochemical hydrogen(H2)production from acidic water electrolysis.Herein we report the one-pot precise synthesis of ultrafine Au core-Pt Au alloy shell nanowires(Au@PtxAu UFNWs).Among them,Au@Pt_0.077 Au UFNWs exhibit the best performance for formic acid oxidation reaction(FAOR)and hydrogen evolution reaction(HER),which only require applied potentials of 0.29 V and-22.6 m V to achieve a current density of 10 m A cm^-2,respectively.The corresponding formic acid electrolyzer realizes the electrochemical H2 production at a voltage of only 0.51 V with 10 m A cm^-2 current density.Density functional theory(DFT)calculations reveal that the Au-riched Pt Au alloy structure can facilitates the direct oxidation pathway of FAOR and consequently elevates the FAOR activity of Au@Pt_0.077 Au UFNWs.This work provides meaningful insights into the electrochemical H₂ production from both the construction of advanced bifunctional electrocatalysts and the replacement of OER.     

Layered Ag-graphene films synthesized by Gamma ray irradiation for stable lithium metal ano des in carb on ate-based electrolytes

Lithium metal batteries are considered as high energy density battery systems with very promising prospects and have bee n widely studied.However,The uncon trollable plating/strippi ng behavior,infinite volume change and den drites formation of lithium metal anode restrict the applicati on.The unc on trolled n ucleati on of lithium caused by the non uniform multi-physical field distributions,can lead to the undesirable lithium deposition.Herein,a graphene composite uniformly loaded with Ag nano-particles(Ag NPs)is prepared through a facile Gamma ray irradiation method and assembled into self-supported film with layered structure(Ag-rGO film).Whe n such film is used as a lithium metal an ode host,the uncontrolled deposition is converted into a highly nucleation-induced process.On one hand,the Ag NPs distributed between the in terlayers of graphe ne can preferentially induce lithium nu cleati on and en able uniform deposition morphology of lithium between interlayers.On the other hand,the stable layered graphene structure can accommodate volume change,stabilize the interface between anode and electrolyte and inhibit dendrites formation.Therefore,the layered Ag-rGO film as anode host can reach a high Coulombic efficiency over 93.3% for 200 cycle(786 h)at a current density of 1 mA cm^-2 for 2 mAh cm^-2 in carbonate-based electrolyte.This work proposes a facile Gamma ray irradiation method to prepare metal/3D-skeleton structure as lithium anode host and demonstrates the potential to regulate the lithium metal deposition behaviors via manipulating the distribution of lithiophilic metal(e.g.Ag)in 3D frameworks.This may offer a practicable thinking for the subsequent design of the lithium metal anode.     

燃放烟花爆竹对空气污染的调查和研究

燃放烟花爆竹是一个历史悠久的民间习俗,在它带来的安全隐患被人们广泛关注的同时,其燃放过程造成的空气污染也不客忽视.本研究通过实验室模拟,测定了燃放一枚鞭炮产生的二氧化硫气体量,并通过收集、分析杭州市区近几年来春节期间空气状况的数据,验证了燃放烟花爆竹造成空气污染的设想,并提出了科学燃放烟花爆竹的方法.     

中国纤维素乙醇技术的研究进展

中国面临着严重的能源短缺和环境污染问题,中国政府正在局部几个省份内政策性鼓励燃料乙醇生产和使用.尽管当前主要是用玉米和谷物作为生产乙醇的原料,然而中国具有大量潜在的低成本的纤维素生物质原料,可以极大地扩大乙醇的产量,降低原料成本.近20年来,由于技术的革命性进步,已使得纤维素乙醇的生产成本从4美元/加仑以上,降低至约1.2-1.5美元/加仑.其中,每吨生物质约44美元.因此,目前乙醇掺汽油具有十分强的市场竞争力.已有几个公司正在建造首批商业纤维素乙醇工厂,虽然这些刚起步的小型设施在合理利用和管理上风险较小,但规模经济需要较大型工厂.尽管配送生物质原料的成本会随需求的增加而增加,但在乙醇生产基础上的生物精炼技术的发展,尤其是化工产品和动力的协同生产,将会使全过程的经济可行性大大提高.进一步深入的基础研究,将解决低成本下实现纤维素的完全利用,以确保在无政策性补贴的前提下,真正使纤维素乙醇成为具有市场竞争力的低成本纯液体燃料.     

Binary ligand strategy toward interweaved encapsulation-nanotubes structured electrocatalyst for proton exchange membrane fuel cell

Hierarchically porous architecture of ir on-nitroge n-carb on(Fe-N-C)for oxyge n reducti on reaction(ORR)is highly desired towards efficient mass transfer in the fuel cell device manner.Herein,we reported a binary ligand strategy to prepare zeolitic imidazolate frameworks(ZIFs)-derived precursors,wherein the addition of secondary ligand endows precursors with the capabilities to transform into porously interweaved encapsulation-nanotubes structured composites after calcination.The optimal catalyst,i.e.,termed as Fe₆-M/C-3,exhibits excellent durability with 88.8%current retention after 50,000 seconds in 0.1 M HClO₄solution by virtue of nanoparticles-encapsulation features,which is more positive than the benchmark commercial 20 wt%Pt/C catalyst.Moreover,a promising maximum power density of Fe₆-M/C-3 as cathode catalyst was also dem on strated in proton exchange membrane fuel cells(PEMFCs)measurements.Therefore,this binary ligand approach to the fabrication of hierarchically porous structures would also have significant implications for various other electrochemical reactions.     

Molten salt as ultrastrong polar solvent enables the most straightforward pyrolysis towards highly efficient and stable single-atom electrocatalyst

Currently,pyrolysis as the most widely used method still has some key issues not well resolved for synthesis of carbon-supported single-atom catalysts(C-SACs),e.g.,the sintering of metal atoms at high temperature as well as the high cost and complicated preparations of precursors.In this report,molten salts are demonstrated to be marvellous medium for preparation of C-SACs by pyrolysis of small molecular precursors(ionic liquid).The ultrastrong polarity on one hand establishes robust interaction with precursor and enables better carbonization,resulting in largely enhanced yield.On the other hand,the aggregation of metal atoms is effectively refrained while no nanoparticle or cluster is formed.By this strategy,a C-SAC with atomically dispersed Fe-N₄ sites and a high specific area over 2000 m² g^-1 is obtained,which illustrates high ORR activity in both acid and alkaline media.Moreover,this SAC exhibits superior methanol tolerance and stability after acid soaking at 85℃ for 48 h.It is believed that the molten-salts-assisted pyrolysis can be developed into a routine strategy as it not only can largely simply the synthesis of C-SACs,but also can be extended to prepare other types of SACs.     

镧对Mg-Si合金中Mg2Si相变质的影响

研究了Mg-5Si合金中La的添加对初生Mg2Si相变质的影响。结果表明,适量的La能够有效地变质初生Mg2Si相。基于本文的研究,在添加约0.5%La时,获得了最佳的变质效果,此时,初生Mg2Si相的尺寸减小到25μm以下,其形态从粗大的树枝形状变为多面体形状。然而,当La增加到0.8%或者更高时,初生Mg2Si相又生长为粗大的树枝形态。而且,在凝固过程中发现形成了一些LaSi2化合物,这些化合物的数量随着La的增加而呈现逐渐增加的趋势。     

电感耦合等离子体质谱法测定天然水体中19种元素

建立STD/KED模式-电感耦合等离子体质谱（ICP-MS）法同时测定天然水体中铍、硼、钛、钒、铬、锰、钴、镍、铜、锌、钼、镉、锑、钡、铊、铅、铁、砷和硒19种元素的分析方法。仪器调谐校准后,样品在线加入锂、钪、铑、铋校准溶液校正,以标准曲线内标法定量分析。标准曲线相关系数均大于0.999,样品加标回收率为92.6%～103.6%,质控样品测定值相对标准偏差为0.20%～2.6%(n=6),方法检出限为0.01～0.70μg/L。该方法灵敏度高,操作简便,节省人力,能满足天然水体中19种元素的同时检测需要。     

二氧化钛纳米管的研究进展

二氧化钛纳米管由于其新奇的光电、催化、气敏等性能引起了广泛的关注,在太阳能电池、光催化、环境净化、气体传感器等领域有潜在的应用价值.本文概述了近年来在制备方法、反应机理和组成、晶型和形貌及掺杂和应用方面的进展,并讨论了今后可能的研究发展方向.     

Uncommon Intramolecular Charge Transfer Effect and Its Potential Application in OLED Emitters

Planarized intramolecular charge transfer(PLICT)state can facilitate the fluorescence process thanks to the relative excellent planarity.Recently,we have discovered that the excited state quinone-conformation induced planarization(ESQIP)occurring on tetraphenylpyrazine(TPP)based derivatives could furnish them with PLICT feature.Unlike to the well-known intramolecular charge transfer,strengthening the electron-donating nature on the donor(D)moiety did not impair the PLICT.The calculation results showed that planarization of the TPP based compounds scarcely accompanied with energy wastage while amount of energy was required for the torsion on geometries.In the polar solvents,the energy consumption for planarization could further decrease,but that for twisting structure would increase.To take advantage of the transformation of the frontier orbitals'distribution,the PLICT type materials would perform a potential application on organic light-emitting diodes(OLEDs).     

超细SiO2负载型水溶性铑膦配合物催化剂研究

用超细SiO2负载水溶性铑膦配合物,并研究其对1-已烯氢甲酰化的催化性能。结果表明,粒径为10-20nm的超细SiO2负载水溶性铑膦配合物所表现的催化活性比颗粒SiO2负载型催化剂高3倍多,且可在较宽的含水量范围内保持高反应活性。当膦铑摩尔比为50,超细SiO2负载型催化剂含水量为25%-55%（质量分数）、烯铑摩尔比为2500、反应温度373K和CO/H2（1/1,体积比）压力4.0MPa的反应条件下,其1-已烯氢甲酰化的反应转化数为450h^-1,产物醛的选择性为100%,醛的n/i比值达3.2。     

低硅铝比ZSM-5分子筛上C4烃的催化裂解反应

以低硅铝比(n(SiO2)/n(Al2O3)=20-45)的ZSM-5分子筛为催化剂, 研究了混合C4烃的催化裂解反应, 并对不同硅铝比的ZSM-5分子筛进行了酸性表征. 混合C4烃的催化裂解反应结果表明, 低硅铝比的ZSM-5分子筛具有较高的低温催化活性, 高硅铝比ZSM-5分子筛催化剂上乙烯和丙烯的收率高于低硅铝比ZSM-5分子筛催化剂, 低硅铝比ZSM-5分子筛上苯和甲苯的收率高于高硅铝比ZSM-5分子筛催化剂. 在反应温度为625 ℃时, 硅铝比为20的ZSM-5分子筛催化剂上乙烯、丙烯、苯和甲苯的总收率可达79.42%. 酸性表征结果表明, 硅铝比低的ZSM-5分子筛具有更多的Bronsted(B)酸酸量、Lewis(L)酸酸量及总酸酸量, 这是低硅铝比ZSM-5分子筛具有低温高活性及高的苯和甲苯收率的原因.     

羰基铑簇合物衍生的多相烯烃氢甲酰化催化剂的性能及红外表征

在常压下,Rh_4(CO)_(12)或Rh_6(CO)_(16)簇合物衍生的Rh/SiO_2对乙烯,丙烯氯甲酰化反应表现出良好的催化活性和选择性,并有利于直线醛的形成.乙烯氢甲酰化体系的表面催化比活性与Rh分散性的关系表明.乙烯氢甲酰化反应具有结构敏感性,而乙烯加氢反应具有结构非敏感性,高分散的金属表面有利于主反应的选择性.通过红外光谱跟踪,发现表面Rh在反应气氛中显示零价.根据接触时间对催化反应的影响,推测多相烯烃氢甲酰化及加氢反应都在Ph~0活性中心上进行.另外,担载羰基铑簇合物的热分解红外研究结果指出,表面羰基化合物金属中心上的配位不饱和性对氢甲酰化催化活性似乎起着重要影响,簇合物只有完全脱羰才能提供高活性的催化中心.在反应气氛和CO气氛中,担载Rh_6(CO)_(16)表现出一致的热稳定性,说明反应气中的CO对稳定羰基物起着主导作用.     

长链烷基二苯基膦—铑配合物催化烯烃氢甲酰化反应研究

研究了烷基二苯基膦-铑配合物RhCl(CO0(n-C8H17PPh2)2(1)和RhCl(Co)(n-C12H25PPh2)2（2）对1-辛烯氢甲酰化反应的催化性能。结果表明,配合物1比2具有更高的催化活性,而配合物2对生成正构醛的选择性更好;当催化剂浓度或膦/铑比增加时,配合物2催化成正构醛的选择性呈下降趋势,显示出与以PPh3为配体时的不同的性能。     

羟基硅酸镁纳米管负载非晶态Co-B催化环己烯氢甲酰化

采用浸渍化学还原法制备羟基硅酸镁纳米管(MgSNTs)负载非晶态钴硼催化剂(Co-B/MgSNTs)。应用X衍射技术(XRD),透射电子显微镜(TEM),X射线光电子能谱仪(XPS),元素分析(ICP)和比表面积(BET)分析等手段对催化剂进行了表征。研究了催化剂对于环己烯氢甲酰化反应的催化活性及循环使用。研究结果表明,具有高比表面积(250 m2·g-1)、较强耐受性和稳定性的MgSNTs可以有效的分散金属粒子,防止活性中心团聚和流失,催化环己烯的转化率为75.8%,醛的选择性为65.8%,实验重复3次以上,催化剂依然保持良好的催化活性和选择性。     

Water/Oil Biphasic Hydroformylation of Higher Olefins over a TPPTS-Rh/SiO2 Catalyst

A novel TPPTS-Rh/SiO2 catalyst, prepared by directly modifying a heterogeneous highsurface-area Rh/SiO2 catalyst with water-soluble TPPTS ligands, could decrease the resistance of mass transfer in water/oil biphasic media for the hydroformylation of higher olefins. The catalytic performance for hydroformylation on this biphasic TPPTS-Rh/SiO2 catalyst system was higher than those of the traditional biphasic HRhCO(TPPTS)3 systems, owing to the chemical bonds between the highly dispersed Rh metal particles and the TPPTS ligands. The catalyst system is applicable for hydroformylation of higher olefins such as 1-dodecene.     

Water／Oil Biphasic Hydroformylation of Higher Olefins over a TPPTS-Rh／SiO2 Catalyst

A novel TPPTS-Rh/SiO2 catalyst, prepared by directly modifying a heterogeneous high-surface-area Rh/SiO2 catalyst with water-soluble TPPTS ligands, could decrease the resistance of masstransfer in water/oil biphasic media for the hydroformylation of higher olefins. The catalytic performancefor hydroformylation on this biphasic TPPTS-Rh/SiO2 catalyst system was higher than those of thetraditional biphasic HRhCO(TPPTS)3 systems, owing to the chemical bonds between the highly dispersedRh metal particles and the TPPTS ligands. The catalyst system is applicable for hydroformylation ofhigher olefins such as 1-dodecene.     

有机-无机杂化L-Rh/SiO2氢甲酰化催化剂的研究Ⅰ.PPh3-Rh/SiO2的催化性能及表征

 利用有机-无机杂化的概念,以三苯基膦直接修饰Rh/SiO2制备了PPh3-Rh/SiO2多相催化剂. 在浆态床烯烃氢甲酰化反应中,该催化剂在10 MPa,373 K温和条件下的活性和选择性远高于Rh/SiO2的活性和选择性,与相应的均相催化剂HRhCO(PPh3)3的性能相当,且具有易分离的优点. 31P MAS NMR和XPS技术表征结果表明,催化剂中的配体PPh3与高度分散的Rh之间存在配位作用,形成了兼具多相和均相催化性能的有机-无机杂化催化剂. 该催化剂对不同碳数烯烃的氢甲酰化反应都具有较好的催化性能.     

Water/Oil Diphasic Hydroformylation of Higher Olefins over a TPPTS-Rh/SiO_2 Catalyst

A novel TPPTS-Rh/SiO2 catalyst, prepared by directly modifying a heterogeneous high-surface-area Rh/SiO2 catalyst with water-soluble TPPTS ligands, could decrease the resistance of mass transfer in water/oil biphasic media for the hydroformylation of higher olefins. The catalytic performance for hydroformylation on this biphasic TPPTS-Rh/SiO2 catalyst system was higher than those of the traditional biphasic HRhCO(TPPTS)3 systems, owing to the chemical bonds between the highly dispersed Rh metal particles and the TPPTS ligands. The catalyst system is applicable for hydroformylation of higher olefins such as 1-dodecene.     

担载型水溶性膦铑配合物催化剂研究

烯类氢甲酰化反应包括了均相催化的某些重要应用。含贵金属和贵重配体的均相催化剂与产物的分离及制备高活性、高选择性、高稳定性催化剂,是均相催化及其多相化最活跃的研究领域之一。对于氢甲酰化催化剂多相化,在基础研究和技术上都仍存在如何解决好催化活性、反应选择性变化或金属流失等问题。将HRh(CO)[P(m-C_6H_4SO_33Na)_3]_3担载在亲水性