聚丙烯腈电纺纤维材料的研究进展

本文综述了静电纺丝法制备聚丙烯腈纤维材料的研究进展,包括聚丙烯腈纳米纤维的制备条件、金属氧化物涂覆聚丙烯腈纳米纤维、聚丙烯腈纳米纤维的碳化、聚丙烯腈/Ag纳米粒子以及聚丙烯腈/碳纳米管复合静电纺丝,对系列丙烯腈共聚物的静电纺丝研究也进行了总结.     

钨基材料在电催化领域的应用进展

目前有关电催化剂应用的诸多研究领域,特别是商业领域,仍然由贵金属及其氧化物占据,但因其存在高成本和易中毒的壁垒而迫使科研人员把研究目光转向钨基电催化材料。氧化钨在制备条件得到有效控制的前提下可实现晶型结构及钨元素价态的多变,因此易于参加多种电化学反应,可实现对特定电化学反应的有效催化。回顾了不同晶相结构氧化钨基电极材料和不同异质结构钨基电极材料的制备方法、结构优势及其对各类电化学反应的优越催化性能,并从电极材料的制备和结构入手深入分析了文中所涉及电极材料优越催化性能的本质原因。以氧化钨及钨基电极材料的优越电催化性能为主线,辅以对电极材料的制备方法和特殊结构的分析,深入探讨了此类电催化材料的优势和发展方向,并总结本领域近5年的科研成果,为此类研究方向的深入开展提供了一定的借鉴经验。     

生物炭基催化剂电催化分解水制氢

近年来低成本的生物炭材料被用于电解水催化剂,对此展开综述.首先介绍电解水制氢基本原理及生物炭基催化剂的制备,再分析炭化温度、活化、杂原子掺杂、金属和/或金属化合物的负载对催化剂微观组成、性质及其催化活性的影响,以期为高效电解水制氢的生物炭基催化剂的制备提供参考.最后为提高电解过程中催化剂的长期稳定性、尤其OER和中性电...     

液体定向输运电纺纤维材料的研究及进展

静电纺丝法是一种高效、便捷制备微/纳米纤维的方法。制备过程中,通过调控微/纳米纤维化学组成及微观结构,能够实现纤维表面及纤维膜厚度方向浸润性差异或梯度的构筑,进而利用浸润性差异或梯度驱动液体的定向输运。综述了近年来电纺纤维及纤维膜材料在液体定向输运中的研究成果及液体定向输运机理,并对液体单向输运微/纳米纤维材料未来的应用及发展进行了展望。     

碳基硫化钼电催化制氢催化剂的研究进展

金属铂是目前最高效的电催化制氢催化剂,但由于铂存在高成本、低储量等缺点,难以适合广泛的工业应用。因此,寻找低成本、高储量的替代电催化制氢催化剂成为未来发展的方向。二硫化钼因具有制氢活性较高、储量丰富、易于制备等优势越来越受到关注。二硫化钼的制氢活性主要取决于暴露的催化活性位数量和导电性。因此,利用纳米碳材料的高导电性和高比表面积来提高二硫化钼的导电性和制氢催化活性位的数量,是制备高活性二硫化钼电催化剂的重要策略之一。重点介绍了二硫化钼电催化制氢的基本原理,以及采用不同碳材料,如石墨烯、氧化石墨烯、碳纳米管等,改进二硫化钼电催化制氢性能的合成方法、催化效果及反应机理。最后,展望了利用碳材料辅助制备高活性、低成本电催化制氢催化剂的前景。     

静电纺聚碳硅烷制备SiOC超细纤维

以聚碳硅烷(PCS)为先驱体, 采用静电纺丝法和先驱体转化法制备SiOC超细纤维, 研究PCS溶液浓度和表面活性剂对纤维形貌和直径的影响。实验结果表明: 添加表面活性剂后, 纤维分布均匀, 串珠现象消失; 通过调节溶液中PCS比例, 纤维直径分布范围为500~900 nm。力学性能测试表明SiOC纤维毡的抗拉强度可达8.88 MPa。SiOC超细纤维毡也展现出优异的热稳定性和抗化学腐蚀性能, 在苛刻环境中可以作为催化剂载体和过滤材料使用。     

基于电催化析氧反应的硫化物催化剂研究进展

氢能作为一种可燃烧的新型能源,凭借其清洁无污染等优点,被认为是人类从根本上解决能源与环境等全球性问题的理想替代能源.电解水是生产高纯度氢气的重要方法之一,也是现代清洁能源技术的重要组成部分.随着实际需求的不断增长,如何利用高效低耗的电催化剂来提升反应速率,已经成为当前新能源领域的研究重点之一.电解水反应由阴极析氢反应(HER)和阳极析氧反应(OER)两个半反应组成,其中HER反应相对容易进行;而相比于HER反应,OER反应动力学缓慢,是影响电解水效率的主要原因.为了提高电解水制氢的能量转化效率,高效OER电催化剂成为研究电解水制氢技术的关键因素.过渡金属催化剂由于其特殊的d轨道结构和在地球上丰富的储备量成为OER催化剂研究领域的热点,但是目前存在的主要问题是,与贵金属催化剂相比,过渡金属催化剂的催化活性较差.因此,发展一些高催化活性和高效稳定的电催化剂,成为该领域研究关注的重点.在过去的十余年间,硫化物、硒化物、磷化物和硼化物等非贵金属基OER电催化剂被大量研究并取得了长足的发展.在这些催化剂中,硫化物型电催化剂不仅具有成本优势,而且在析氧过电位、耐久性等方面正在接近甚至超越RuO2和IrO2等贵金属催化剂,颇具应用潜力.本文主要介绍了电解水析氧反应在不同电解质中的反应机理,从硫化物型OER电催化剂的物理化学性质入手,证实了硫化物型OER电催化剂在析氧反应中具有独特的优势,最后综述了有关硫化物型OER电催化剂在改进策略等方面的研究进展.     

Hydrogen evolution from water splitting on nanocomposite photocatalysts

The photocatalytic production of H₂ in one step is potentially one of the most promising ways for the conversion and storage of solar energy. The paper overviews our recent studies on the photocatalysts splitting water into hydrogen under irradiation. The attention was mainly focused on the promotion effects of nanosized modifications in the interlayer and surface of photocatalysts for hydrogen evolution with visible light. The photocatalytic activity depended significantly on modification techniques, such as loading, proton exchange, and intercalation. The formation of a ‘‘nest’’ on the particle surface promoted a uniform distribution and strong combination of the nanosized particles on the surface of catalysts. By the methods of intercalation and pillaring as well as by selecting both host and guest, a large variety of molecular designed host–guest systems were obtained. Cadmium sulfide (CdS)-intercalated composites showed higher activity and stability. This activity of K₄Ce₂M₁₀O₃₀ (M = Ta, Nb) evolving H₂ under visible light irradiation was enhanced by the incorporation of Pt, RuO₂ and NiO as co-catalysts. Especially, the nanosized NiO_x (Ni–NiO double-layer structure) greatly prompted the photocatalytic H₂ evolution significantly.     

Hydrogen production from water splitting of real-time industry effluent using novel photocatalyst

The simultaneous degradation of real-time industrial effluent and hydrogen production was carried out in this study, taking into account the global clean energy demand. A novel photocatalyst based on a metal–organic framework and spindle-shaped titanium dioxide nanoparticles was synthesized to perform photocatalytic water splitting reactions. The resulting composite (MIL-53@TiO_2, MIL: Matériaux de l′Institut Lavoisier) was characterized by standard analytical methods. The photocatalytically active MIL-53@TiO₂ composite produced hydrogen without using any sacrificial agents. The hydrogen production was observed to be 0.26 mmol in the presence of TiO₂ which increased to 7.9 mmol in the presence of MIL-53@TiO₂ composite after 180 min of irradiation. The corresponding hydrogen evolution rate was 26.33 mmol h^-1g^?1, which was observed 30 times higher than the pristine materials. The remarkable photoactivity was due the superior charge separation property and less recombination of the charge carrier pair in the MIL-53@TiO₂ composite. Furthermore, the photocatalyst exhibited excellent reusability for hydrogen production up to 4 cycles. The results shown in the present work may be extended for large-scale applications.     

Hydrogen production from water by thermochemical cycles

It is expected that in the future hydrogen will play a major role in the storage, distribution, and usage of energy involving its various physical states: gaseous—solid hydride—cryogenic liquid. One of the most modern concepts for the production of hydrogen from water, thermochemical cycles, is reviewed and a compilation of 72 published cycles is presented.     

Revealing the effect of anion-tuning in bimetallic chalcogenides on electrocatalytic overall water splitting

Enhancing electrocatalytic water splitting performance by modulating the intrinsic electronic structure is of great importance. Here, porous bimetallic oxide and chalcogenide nanosheets grown on carbon paper denoted as NiCo₂X₄/CP (X = O, S, and Se) are prepared to demonstrate how the anion components affect the electronic structures and thereby disclose the correlation between their intermediates interaction and catalytic activities. The experimental characterization and theoretical calculation demonstrate that Se and S substitution can promote the ratio of Co³⁺/Co²⁺ and thereby modulate the electronic structure accompanied with the upshift of d band centers, which not only enhance the inner conductivity but also regulate the interaction between the catalyst surface and intermediates, especially for the adsorption of absorbed H and hydroperoxy intermediates towards respective hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). As a result, a full alkaline electrolyzer using NiCo₂Se₄/CP and NiCo₂S₄/CP as cathode and anode delivers a low voltage of 1.51 V at 10 mA·cm⁻², which is comparable even superior to most transition metal-based electrolyzers.

     

Ultrafine porous fibers electrospun from cellulose triacetate

Ultrafine porous cellulose triacetate (CTA) fibers were prepared by electrospinning with methylene chloride (MC) and a mixed solvent of MC/ethanol (EtOH) and their intra- and inter-fiber pore structures was investigated. Ultrafine porous CTA fibers electrospun with MC had isolated circular shape pores with a narrow size distribution in the range of 50–100 nm. In the case of ultrafine CTA fibers electrospun with MC/EtOH (90 / 10 v/v), they had interconnected larger pores in the range of 200–500 nm. These porous structures were induced by phase separation resulting from the rapid evaporation of solvent during the electrospinning process. However, non-porous corrugated fibers were obtained from MC/EtOH (85 / 15 v/v) and MC/EtOH (80 / 20 v/v) due to their lower vapor pressure. The pore sizes in ultrafine CTA fibers electrospun with MC showed a bimodal distribution centered at ∼17 and ∼64 nm. CTA fibers electrospun with MC/EtOH (90 / 10 v/v) showed the greatest porosity due to their larger intra-fiber pores and fiber diameter.     

Reaction environment self-modification on low-coordination Ni2+ octahedra atomic interface for superior electrocatalytic overall water splitting

Large scale synthesis of high-efficiency bifunctional electrocatalyst based on cost-effective and earth-abundant transition metal for overall water splitting in the alkaline environment is indispensable for renewable energy conversion. In this regard, meticulous design of active sites and probing their catalytic mechanism on both cathode and anode with different reaction environment at molecular-scale are vitally necessary. Herein, a coordination environment inheriting strategy is presented for designing low-coordination Ni²⁺ octahedra (L-Ni-8) atomic interface at a high concentration (4.6 at.%). Advanced spectroscopic techniques and theoretical calculations reveal that the self-matching electron delocalization and localization state at L-Ni-8 atomic interface enable an ideal reaction environment at both cathode and anode. To improve the efficiency of using the self-modification reaction environment at L-Ni-8, all of the structural features, including high atom economy, mass transfer, and electron transfer, are integrated together from atomic-scale to macro-scale. At high current density of 500 mA/cm², the samples synthesized at gram-scale can deliver low hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) overpotentials of 262 and 348 mV, respectively.

     

NiFe-植酸复合物的室温制备及其全解水电催化性能

制备高稳定性、高活性双功能催化剂用于全解水制氢是氢能源大规模商业化应用的重要环节之一。本文以植酸(PA)、六水合氯化铁(FeCl₃·6H₂O)和六水合氯化镍(NiCl₂·6H₂O)为原料,采用两步室温浸渍法在泡沫镍(NF)上制备了片状无定形植酸-镍铁双金属复合材料(NiFe-PA)。采用线性扫描伏安法(LSV)考察了NiFe-PA修饰NF电极(NiFe-PA/NF)在碱性条件(1.0 mol/L KOH)的电解水催化性能。实验结果表明：由于NiFe双金属之间的协同效应,NiFe-PA/NF作为双功能催化剂显示出优越的析氧和析氢性能。NiFe-PA/NF电极在50 mA·cm^-2电流密度下析氧反应的过电位仅需220 mV;在10 mA·cm^-2电流密度下的析氢反应的过电位为135 mV。将NiFe-PA/NF组装成双电极系统用于全解水,达到10 mA·cm^-2电流密度的电池电压仅需1.61 V,低于贵金属催化剂体系RuO₂