Three-dimensional porous photo-thermal fiber felt with salt-resistant property for high efficient solar distillation

The urgent need for fresh water resource is a public issue facing the world. Solar distillation for seawater desalination is a promising freshwater production method. Interfacial solar evaporation systems based on 2D photo-thermal membranes have been widely studied, but salt pollution is one of the main challenges for solar distillation. In order to solve this problem, a hydrophilic three-dimensional (3D) porous photo-thermal fiber felt (PFF) was obtained by one-step method, through a simple polydopamine (PDA) coating method with hydrophobic graphite felt as a substrate. The PFF had a good evaporation rate of 1.48 kg m^?2 h^-1 and its corresponding light-vapor conversion efficiency reached 87.4%. In addition, the PFF exhibited an excellent salt-resistant ability when applied to photo-thermal evaporation of high-salinity seawater with 10 wt% NaCl, owing to its intrinsic 3D macroporous structure for the migration circulation of salt ions. The development of the PFF offers a new route for the exploration of salt-resistant photo-thermal materials and is promising for the practical application of solar distillation.     

网状骨架CVD生长碳纳米管用于重盐水脱盐

目前,太阳能海水淡化领域通过光子管理、纳米尺度热调控、开发新型光热转换材料、设计高效光吸收太阳能蒸馏器等方法实现了界面太阳能驱动蒸汽生成,这种绿色、可持续的脱盐技术已成为近年来的研究热点。碳基材料如碳纳米管、石墨烯、炭黑、石墨等都有涵盖整个太阳光光谱的光吸收能力,是一类新型的光热转换材料。本文通过对材料进行微结构设计,使用化学气相沉积(CVD)技术,在不锈钢网状骨架上生长碳纳米管形成光热转换活性区,以实现高效光吸收、光热转换,并进一步设计了房屋型太阳能蒸发器,其中盐水表面被微米网状-碳纳米管蒸发膜覆盖,利用光热转换过程产生的热量驱动重盐水中的水蒸发产生水蒸气,最后对水蒸气进行冷凝回收实现脱盐。实验结果表明,当光照强度为1个太阳光(1 kW·m~(-2))时,膜表面温度迅速升高并稳定于84.37°C,对于重盐水(100 g·L~(-1) NaCl)的脱盐率达到99.92%,可实现稳定持续的重盐水脱盐。这种方法可用于构建多孔界面光热转换脱盐系统,对设计界面光蒸汽转化膜材料及器件,实现规模化海水淡化具有重要的意义。     

Reduced Graphene Oxide/Carbon Fiber Composite Membrane for Self-floating Solar-thermal Steam Production

Solar-thermal water evaporation has attracted increasing attention owing to the promising potential to solve the global clean water and energy crisis. But, the development of this strategy is limited by the lack of materials with high solar-thermal conversion efficiency, local heating of superficial water, easy preparation and low cost. Herein, we proposed a facile strategy to prepare a reduced graphene oxide/carbon fiber composite membrane, denoted as RGO/CF membrane. The surface of the RGO/CF membrane was highly hydrophobic, endowing the composite membrane with the self-floating ability on the water without any assistance. The light absorbance ability achieved as high as ca. 98% in the wavelength range of 300-1200 nm. The steam evaporation efficiency under the illumination of 3-sun was 97%, generating water steam at a rate of 4.54 kg·m^-2·h^-1. Moreover, the solar-thermal steam production rate showed high stability during successive 30 cycle tests.     

参杂缺陷石墨烯的高分子复合材料导热特性分子动力学模拟

Polymers are widely used advanced materials composed of macromolecular chains, which can be found in materials used in our daily life. Polymer materials have been employed in many energy and electronic applications such as energy harvesting devices, energy storage devices, light emitting and sensing devices, and flexible energy and electronic devices. The microscopic morphologies and electrical properties of the polymer materials can be tuned by molecular engineering, which could improve the device performances in terms of both the energy conversion efficiency and stability. Traditional polymers are usually considered to be thermal insulators owing to their amorphous molecular chains. Graphene-based polymeric materials have garnered significant attention due to the excellent thermal conductivity of graphene. Advanced polymeric composites with high thermal conductivity exhibit great potential in many applications. Therefore, research on the thermal transport behaviors in graphene-based nanocomposites becomes critical. Vacancy defects in graphene are commonly observed during its fabrication. In this work, the effects of vacancy defects in graphene on thermal transport properties of the graphene-polyethylene nanocomposite are comprehensively investigated using molecular dynamics (MD) simulation. Based on the non-equilibrium molecular dynamics (NEMD) method, the interfacial thermal conductance and the overall thermal conductance of the nanocomposite are taken into consideration simultaneously. It is found that vacancy defects in graphene facilitate the interfacial thermal conductance between graphene and polyethylene. By removing various proportions of carbon atoms in pristine graphene, the density of vacancy defects varies from 0% to 20% and the interfacial thermal conductance increases from 75.6 MW·m⁻²·K⁻¹ to 85.9 MW·m⁻²·K⁻¹. The distinct enhancement in the interfacial thermal transport is attributed to the enhanced thermal coupling between graphene and polyethylene. A higher number of broken sp² bonds in the defective graphene lead to a decrease in the structure rigidity with more low-frequency (< 15 THz) phonons. The improved overlap of vibrational density states between graphene and polyethylene at a low frequency results in better interfacial thermal conductance. Moreover, the increase in the interfacial thermal conductance induced by vacancy defects have a significant effect on the overall thermal conductance (from 40.8 MW·m⁻²·K⁻¹ to 45.6 MW·m⁻²·K⁻¹). In addition, when filled with the graphene layer, the local density of polyethylene increases on both sides of the graphene. The concentrated layers provide more aligned molecular arrangement, which result in better thermal conductance in polyethylene. Further, the higher local density of the polymer near the interface provides more atoms for interaction with the graphene, which leads to stronger effective interactions. The relative concentration is insensitive to the density of vacancy defects. The reported results on the thermal transport behavior of graphene-polyethylene composites provide reasonable guidance for using graphene as fillers to tune the thermal conduction of polymeric composites.     

氧化石墨烯基柔性发电机的构筑及其水蒸发发电性能

如何利用自然界广泛存在的水蒸发能是一个具有挑战性的课题。 以表面具有丰富官能团和优异亲水性的氧化石墨烯(GO)做发电材料,以肼还原制备的还原氧化石墨烯(RGO)作电极材料,通过简单滴注法在聚对苯二甲酸乙二酯(PET)衬底上构筑GO/RGO的柔性发电机,并研究其水蒸发诱导的发电性能。 结果表明,固定GO薄膜发电机的工作面积为4.5 cm×1.5 cm,以室温自然水蒸发为驱动力,可以输出90 mV的开路电势(V_oc)以及0.6 μA的短路电流(I_sc),最大功率密度可达1.25 μW/cm³。 该驱动器同时展示出优异的柔性和较高的稳定性。 通过控制体系的水蒸发发生与否,并基于经典流动电势理论,提出了水蒸发诱导的GO/RGO柔性发电机的发电机制。 提出了步骤简易、成本低廉、性能稳定的水蒸发驱动的发电机制备新思路,为新型水蒸发能的利用提供了新途径。     

PVDF⁃CNT自漂浮多孔微珠的制备及在高效太阳能驱动界面水蒸发中的应用

采用操作便捷的相转化法制备了可用于太阳能驱动界面水蒸发的聚偏氟乙烯-碳纳米管(PVDF-CNT) 自漂浮多孔微珠. PVDF-CNT微珠独特的组成和多孔微球结构有助于实现太阳光的高效捕获、 充分的水运 输和快速的蒸汽逸出, 且CNTs含量越高, PVDF-CNT微珠性能越佳. PVDF-CNT微珠最多可吸收约94.5％的太阳光, 2 min内使水面温度从20.8 ℃升高至43.1 ℃. 在1 kW/m²的太阳光模拟器照射下, 水蒸发速率高达1.501 kg/(m²·h), 太阳能转换效率高达94.2%.     

由单层薄水铝石制备的活性氧化铝处理水中氟离子

The preparation of high-efficiency and low-cost adsorbents for the defluoridation of drinking water remains a huge challenge. In this study, single-layer and multi-layer boehmite were first synthesized via an organic-free method, and active alumina used for fluoride removal from water was obtained from the boehmite. The advantage of a single layer is that more aluminum is exposed to the surface, which can provide more adsorption sites for fluoride. The active alumina adsorbent derived from single-layer boehmite exhibits a high specific surface area and excellent adsorption capacity. The high surface area ensures a high adsorption capacity, and the organic-free synthesis method lowers the preparation cost. The as-prepared adsorbent was characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Fourier-transform infrared spectroscopy (FTIR) and nitrogen adsorption-desorption analysis. The single-layer structure of boehmite was determined from the simulated XRD diffraction pattern of single-layer boehmite. The disappearance of the (020) diffraction peak of boehmite illustrates that the dimensions in the b direction are extremely small, and according to the XRD simulation results, the single-layer structure of boehmite could be determined. Single-layer boehmite with a surface area of 789.4 m²·g^-1 was formed first. The active alumina obtained from the boehmite had a surface area of 678.4 m²·g^-1, and the pore volume was 3.20 cm³·g^-1. The fluoride adsorption of the active alumina was systematically studied as a function of the adsorbent dosage, contact time, concentration, co-existing anions, and pH. The fluoride adsorption capacity of the active alumina obtained from the single-layer boehmite reached up to 67.6 mg·g^-1, which is higher than those of most alumina adsorbents reported in the literature. The adsorption capacities of the active alumina are related to the specific surface area and the number of hydroxyl groups on the surface. Dosages of 0.6, 1.0, and 2.6 g·L^-1 of active alumina were able to lower the 10, 20, and 50 mg·L^-1 fluoride solutions, respectively, below the maximum permissible limit of fluoride in drinking water in China (1.0 mg·L^-1), suggesting that the active alumina synthesized in this work is a promising adsorbent for defluoridation of drinking water. In addition, the fluoride adsorption is applicable in a wide pH range from 4 to 9 and is mainly interfered by SO₄^2- and PO₄^3-. Further investigation suggested that the fluoride adsorption of the active alumina follows the pseudo second-order model and Langmuir isotherm model     

蓝宝石衬底上化学气相沉积法生长石墨烯

化学气相沉积(CVD)法是制备大面积、高质量石墨烯材料的主要方法之一,但存在衬底转移和碳固溶等问题,本文选用蓝宝石衬底弥补了传统CVD法的不足。利用CVD法在蓝宝石衬底上生长石墨烯材料,研究生长温度对石墨烯表面形貌和晶体质量的影响。原子力显微镜(AFM)、光学显微镜(OM)、拉曼光谱和霍尔测试表明,低温生长有利于保持材料表面的平整度,高温生长有利于提高材料的晶体质量。研究氢气和碳源对蓝宝石衬底表面刻蚀作用机理,发现氢气对蓝宝石衬底有刻蚀作用,而单纯的碳源不能对衬底产生刻蚀效果。在1200 ℃下,直径为50 mm的晶圆级衬底上获得平整度和质量相对较好的石墨烯材料,室温下载流子迁移超过1000 cm²·V^-1·s^-1。     

石墨炔与锡烯层状体系的形变势和电声耦合及载流子传输理论研究

我们对sp + sp²杂化的碳同素异形体—石墨炔,以及锡烯等层状体系的电子结构、形变势、电声耦合和电荷输运性质进行了回顾。有些二维石墨炔具有类似石墨烯的狄拉克锥,同时石墨炔电子结构可通过将其沿不同方向裁剪成不同宽度一维纳米带来调节。采用玻尔兹曼输运方程和形变势近似,结合第一性原理计算,我们预测石墨炔电荷载流子室温迁移率可达10⁴–10⁵ cm²·V^-1·s^-1,尤其6, 6, 12-石墨炔,因有两个狄拉克锥及比石墨烯弱的电声耦合,其室温迁移率甚至能高于石墨烯。因此具有独特电子结构和高迁移率的石墨炔能成为继石墨烯之后未来的纳米电子器件材料。此外我们着重分析了形变势方法的适用性：密度泛函微扰理论和瓦尼尔插值技术能精确计算任意波矢和模式的声子对载流子散射,该方法在石墨烯和石墨炔上的运用表明二维平面碳材料中对载流子输运起主导作用的是长波长纵声学声子散射,因而形变势方法是适用的;但通过对锡烯等二维非平面buckling结构的材料声子散射和迁移率的计算,发现此类不具备σ_h对称性的材料有较强的面外声子散射和横声学声子谷间散射,使得常用的形变势失效。     

钴-聚吡咯-碳载PtNi燃料电池催化剂的制备及应用

采用脉冲微波辅助化学还原合成新型载体钴-聚吡咯-碳(Co-PPy-C)负载PtNi催化剂.利用透射电镜(TEM)和X射线衍射(XRD)研究了催化剂的结构和形貌,此外,利用循环伏安(CV)和线性扫描伏安(LSV)等方法测试了催化剂的电化学活性及耐久性. PtNi/Co-PPy-C催化剂的金属颗粒直径约为1.77 nm,催化剂在载体上分布均匀且粒径分布范围较窄. XRD结果显示, PtNi/Co-PPy-C中Pt(111)峰最强, Pt主要是面心立方晶格.CV结果显示,其电化学活性面积(ECSA)为72.5 m²·g^-1,明显高于商用催化剂Pt/C(JM)的56.9 m²·g^-1.为进一步考查催化剂耐久性,电化学加速5000圈耐久性测试后, PtNi/Co-PPy-C颗粒发生明显集聚, ECSA衰减率和0.9 V下比质量活性衰减率分别为38.2%和63.9%.此外,采用有效面积为50 cm²的单电池用于评价自制催化剂的性能,发现在70 ℃且背压为50 kPa时电池的性能最好,此时自制PtNi/Co-PPy-C催化剂制备膜电极(MEA)的最大功率密度达到523 mW·cm^-2.可见自制催化剂的电化学性能高于商用Pt/C(JM),在质子交换膜燃料电池(PEMFC)领域有一定的应用前景.     

小晶粒ZSM-5沸石的绿色、经济性合成

通过添加少量silicalite-1做为活性晶种在较宽的SiO₂/Al₂O₃比范围内制备得到了小晶粒ZSM-5沸石,对所得样品进行X射线衍射(XRD),扫描电子显微镜(SEM),透射电子显微镜(TEM),N₂吸附-脱附,氨程序升温脱附(NH₃-TPD)以及吡啶吸附红外(Py-IR)表征。研究结果表明活性晶种能有效导向生成ZSM-5沸石,避免杂晶形成并可减小所得沸石的晶粒尺寸;所得ZSM-5在低硅铝比(SiO₂/Al₂O₃ ratio = 30)时呈纳米颗粒聚集体形貌,具有多级孔道结构性质;在较高硅铝比时(SiO₂/Al₂O₃ ratio = 60–120)呈小晶粒形貌,颗粒尺寸大约200 nm。值得注意的是由胶态晶种引入的少量TPAOH不完全堵塞沸石的微孔孔道,因此所得所有沸石均无需提前焙烧除去模板剂即可进行离子交换得到具有酸性的H型ZSM-5沸石,所得酸性H型ZSM-5沸石具有和常规方法得到的相同SiO₂/Al₂O₃比的ZSM-5相似的酸类型、强度和酸量,在催化甲醇转化制备烯烃时呈现出相似的甲醇转化率和烯烃选择性。与常规ZSM-5制备方法比较,该方法能够大大减少模板剂的使用量,避免了样品离子交换前的焙烧,方法绿色清洁、成本低廉,具有很好的潜在的工业应用前景。     

富氮多级孔炭材料的制备及其吸附分离CO2的性能

使用新型含氮聚合物席夫碱为炭源, SBA-15为模板,通过纳米铸型法原位合成微孔-中孔-大孔串联的多级孔富氮炭材料.材料的比表面积为752 m²·g^-1,孔容0.79 cm³·g^-1; X光电子能谱分析表明炭材料中的氮含量高达7.85%(w).将所制备的多孔炭材料应用于CO₂的吸附分离,发现炭材料的微孔发挥主导作用,表面氮掺杂发挥辅助作用.在两者的协同作用下, CO₂吸附量在常压、273 K下可达97 cm³·g^-1, CO₂/N₂和CO₂/CH₄的分离比(摩尔比)分别为7.0和3.2,低压亨利吸附选择性分别为23.3和4.2.采用Toth模型对单组分平衡吸附进行拟合,并根据理想溶液吸附理论(IAST)预测双组分CO₂/N₂和CO₂/CH₄混合气体的分离选择性分别为40和18.     

基于混合溶剂有机电解液的超低温孔洞石墨烯超级电容

适用于极低温环境的石墨烯超级电容具有广阔的应用前景。然而,由于片层间严重的堆叠团聚,目前石墨烯超级电容的低温储能性能并不理想。本文使用H₂O₂氧化刻蚀法制备了孔洞石墨烯(rHGO),将传统有机溶剂碳酸丙烯酯(PC)和低凝固点溶剂甲酸甲酯(MF)混合制备了混合溶剂有机电解液,组装获得了能够在-60 ℃极低温环境下稳定工作的超级电容。结果表明,该超级电容在-60 ℃下的比电容为106.2 F·g^-1,相对于常温电容(150.5 F·g^-1)的性能保持率高达70.6%,显著优于未做处理的石墨烯(52.3%)以及文献中的其他石墨烯材料。得益于孔洞化形貌中丰富的介孔和大孔所形成的离子传输通道和缩短的离子传输路径,孔洞石墨烯内的离子扩散阻抗远小于普通石墨烯,且受温度降低的影响更小。在-60 ℃的极低温条件下,该超级电容表现出26.9 Wh·kg^-1的最大能量密度和18.7 kW·kg^-1的最大功率密度,优于传统碳材料的低温超级电容性能。-60 ℃时在5 A·g^-1电流密度下循环充放电10000次后电容保持率达89.1%,具有良好的低温循环稳定性。     

热剥离法制备石墨烯纳米片对Pb2+和Cd2+的吸附

石墨粉氧化后,在氮气气氛下,快速高温剥离制得石墨烯纳米片。采用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(HRTEM)、拉曼(Raman)光谱、傅里叶变换红外(FT-IR)光谱和氮气吸附-脱附等分析手段对石墨烯样品进行了表征。这些分析测试结果显示:石墨烯样品主要由很薄的1-4层石墨组成,呈褶皱状态,比表面积为628.5 m²·g^-1。研究了石墨烯吸附水溶液中的Pb²⁺和Cd²⁺的pH值、吸附时间、吸附温度和金属离子初始浓度等影响因素, Pb²⁺和Cd²⁺的最大吸附量分别为460.20和72.39 mg·g^-1。结果表明,热剥离法制得的高质量石墨烯纳米片可以作为一种高效的从水中去除Pb²⁺和Cd²⁺的吸附材料。     

Acetic Acid Assistant Hydrogenation of Graphene Sheets with Ferromagnetism

Ferromagnetism of pure carbon-based materials has been widely researched for several years. In therocially and experimentally, semi-hydrogenation graphene sheets exhibit ferromagnitism, which is related to the degree of hydrogenation. Here we reported the controllable hydrogenation of graphene using ball-milling method with acetic acid as hydrogenating agent. The hydrogenation graphene sheets were characterized by means of transmission electron microscopy(TEM), Raman spectroscopy and X-ray photoelectron spectroscopy, and magnetic measurement. The relusts of Raman spectroscopy demonstrate that the relative intensity of D band increases with the hydrogenation degree. The resluts of magnetic meansurement indicate the maximal magnetic moment of 0.274 A·m²/kg at 2 K for semi-hydrogenation graphene.     

Preparation of an Anti-Aggregation Silica/Zinc/Graphene Oxide Nanocomposite with Enhanced Adsorption Capacity

Nanomaterials play a significant role in adsorption treatment of dye wastewater, but irreversible aggregation of nanoparticles poses a significant problem. In this work, nanomesoporous zinc-doped silicate (NMSZ) was prepared by an in situ method. To prevent agglomeration, NMSZ was covalently bonded to graphene oxide (GO) sheets to form a nano-silica/zinc/graphene oxide composite (GO-NMSZ), aimed at removal of cationic dye methylene blue (MB). For comparison, undoped mesoporous silica (MS) was also synthesized and modified to obtain a silica/graphene oxide composite (GO-MS). The materials were characterized by powder XRD, SEM, FTIR spectroscopy, TEM, nitrogen sorption, and X-ray photoelectron spectroscopy (XPS). Preservation of the oxygen-containing groups of GO in the composites led to higher adsorption capacities. The best GO-NMSZ composite exhibited an enhanced adsorption capacity of 100.4 mg g⁻¹ for MB compared to those of undoped GO-MS (80.1 mg g⁻¹) and nongrafted NMSZ (55.7 mg g⁻¹). The nonselective character of GO-NMSZ is demonstrated by effective adsorption of anionic dye Congo red (127.4 mg g⁻¹) and neutral dye isatin (289.0 mg g⁻¹). The adsorption kinetics, adsorption isotherms, and a thermodynamic study suggested that MB adsorption occurs by chemisorption and is endothermic in nature.     

聚乙烯醇载银海绵的制备及界面光热驱动水蒸发性能

利用光热材料的太阳能水蒸发技术是一种绿色、 环保地解决淡水资源短缺的重要技术, 但光热材料的制备成本、 蒸发效率和热损失等因素限制了其推广应用. 本文采用一锅法制备了聚乙烯醇载银海绵(AgNPs/PVA)太阳能界面蒸发器, 并研究了AgNPs含量对AgNPs/PVA在太阳能驱动水蒸发过程中光热性能的影响. 研究结果表明, 当AgNPs的质量为PVA的10%时, 制备的AgNPs/PVA在1 kW/m ²的太阳光强度下具有最优的蒸发速率, 水蒸发速率可达1.62 kg?m ^?2?h ^?1, 为纯水(0.42 kg?m ^?2?h ^?1)的3.9倍. 本文制备的AgNPs/PVA具有制备工艺简单、 亲水性能优良和蒸发性能良好的特点, 在太阳能驱动水蒸发领域具有较大的应用前景.     

微波辅助快速制备2D/1D ZnIn2S4/TiO2 S型异质结及其光催化制氢性能

The threat and global concern of energy crises have significantly increased over the last two decades. Because solar light and water are abundant on earth, photocatalytic hydrogen evolution through water splitting has been considered as a promising route to produce green energy. Therefore, semiconductor photocatalysts play a key role in transforming sunlight and water to hydrogen energy. To date, various photocatalysts have been studied. Among them, TiO₂ has been extensively investigated because of its non-toxicity, high chemical stability, controllable morphology, and high photocatalytic activity. In particular, 1D TiO₂ nanofibers (NFs) have attracted increasing attention as effective photocatalysts because of their unique 1D electron transfer pathway, high adsorption capacity, and high photoinduced electron–hole pair transfer capability. However, TiO₂ NFs are considered as an inefficient photocatalyst for the hydrogen evolution reaction (HER) because of their disadvantages such as a large band gap (~3.2 eV) and fast recombination of photoinduced electron–hole pairs. Therefore, the development of a high-performance TiO₂ NF photocatalyst is required for efficient solar light conversion. In recent years, several strategies have been explored to improve the photocatalytic activity of TiO₂ NFs, including coupling with narrow-bandgap semiconductors (such as ZnIn₂S₄). Recently, microwave (MW)-assisted synthesis has been considered as an important strategy for the preparation of photocatalyst semiconductors because of its low cost, environment-friendliness, simplicity, and high reaction rate. Herein, to overcome the above-mentioned limiting properties of TiO₂ NFs, we report a 2D/1D ZnIn₂S₄/TiO₂ S-scheme heterojunction synthesized through a microwave (MW)-assisted process. Herein, the 2D/1D ZnIn₂S₄/TiO₂ S-scheme heterojunction was constructed rapidly by using in situ 2D ZnIn₂S₄nanosheets decorated on 1D TiO₂ NFs. The loading of ZnIn₂S₄ nanoplates on the TiO₂ NFs could be easily controlled by adjusting the molar ratios of ZnIn₂S₄ precursors to TiO₂ NFs. The photocatalytic activity of the as-prepared samples for water splitting under simulated solar light irradiation was assessed. The experimental results showed that the photocatalytic performance of the ZnIn₂S₄/TiO₂ composites was significantly improved, and the obtained ZnIn₂S₄/TiO₂ composites showed increased optical absorption. Under optimal conditions, the highest HER rate of the ZT-0.5 (molar ratio of ZnIn₂S₄/TiO₂= 0.5) sample was 8774 μmol·g^-1·h^-1, which is considerably higher than those of pure TiO₂ NFs (3312 μmol·g^-1·h^-1) and ZnIn₂S₄nanoplates (3114 μmol·g^-1·h^-1) by factors of 2.7 and 2.8, respectively. Based on the experimental data and Mott-Schottky analysis, a possible mechanism for the formation of the S-scheme heterojunction between ZnIn₂S₄ and TiO₂ was proposed to interpret the enhanced HER activity of the ZnIn₂S₄/TiO₂heterojunctionphotocatalysts.      

二氧化硅包覆的杂多酸在双氧水存在条件下催化氧化甘油

催化剂的酸性和氧化还原性在催化生物质平台分子转化过程中起着非常重要的作用,杂多酸具有较强的酸性以及优良的氧化还原性,因而杂多酸在生物质催化转化领域备受关注。本文利用溶胶-凝胶法和硅烷化方法将杂多酸催化剂封装在二氧化硅载体内部,随后以傅立叶红外光谱、X-射线衍射仪、热重分析仪、透射电子显微镜、扫描电镜等手段对合成的材料进行了表征。红外光谱表明杂多酸在催化剂中保持了其完整结构,X-射线衍射表明杂多酸高度分散在二氧化硅载体上,电镜表征显示催化剂呈球形纳米颗粒形貌。基于以上表征结果,我们将包覆的杂多酸催化剂应用于甘油氧化,在以过氧化氢为氧化剂,温和反应条件下,合成的材料对甘油氧化具有良好的催化活性,其中对甲酸的选择性大约为70%,对乙醇酸的选择性大约为27%。硅烷化过程对于催化剂循环起着重要的作用,单纯二氧化硅的比表面积为287 m²·g^-1,二氧化硅包覆杂多酸经过硅烷化后,其比表面积降为245 m²·g^-1,而且孔径也有所降低。单纯二氧化硅与水的接触角为0°,而二氧化硅包覆的杂多酸在硅烷化之后的催化剂具有很强的疏水性,与水的接触角为137°。根据这些催化剂表征数据说明硅烷化过程不仅可以显著提高催化剂的疏水性,而且同时限制了载体孔径,阻止杂多酸流失到反应体系中,与传统的浸渍法将杂多酸负载在二氧化硅载体上得到的催化剂相比,催化剂的循环利用性显著提高。反应后的催化剂结构与新鲜催化剂相比,并没有发生明显变化。催化剂经过一次循环后,表面暴露了更多的活性中心,活性稍有提高。催化剂在反应体系中加入强质子酸可以显著提高反应的催化性能,揭示了Bronsted酸在甘油氧化过程中对甘油分子的活化起着重要的作用。     

石墨烯三维结构组装体制备及光热水蒸发和水处理研究进展

水资源短缺是世界长期面临的问题,当前全球80多个国家的约15亿人口面临淡水不足,其中26个国家的3亿人口完全生活在缺水状态。近年来,人们开发了新型太阳能界面水蒸发材料和技术,能够利用高效光热材料吸收太阳能转化为热能,实现大量的、快速的水蒸发,冷凝后收集便得到洁净水,是一种高效、绿色、低成本水处理和解决水资源短缺的方法。石墨烯三维组装体材料的物理和化学性质优异,光热转化效率高,同时其太阳光吸收率高,内部微纳孔道丰富,具有良好的水传输通道,表面水蒸发面积大,在太阳光照射下能够实现超高的水蒸发速率,在光热水处理方面展现了巨大的科学研究意义和实用价值。本文将综述石墨烯三维组装体的制备及光热水处理方面的研究进展,包括石墨烯三维结构组装体制备方法,其光热水蒸发性能,总结了石墨烯三维结构组装体在光热水蒸发及水处理方面的应用,最后分析了石墨烯三维结构组装体光热水处理面临的问题及展望。