模板组装制备多孔SiO_2及其在纳米材料中的应用

采用不同的几何模板 ,通过溶胶 -凝胶过程 ,探索了模板组装制备孔径形状、尺寸大小可控的微孔氧化硅材料 ;讨论了模板组装合成材料的孔径控制 。

多孔TiO_2薄膜自洁净玻璃的亲水性和光催化活性

亲水性多孔 Ti O2 薄膜自洁净玻璃以含聚乙二醇的钛醇盐溶胶前驱体中通过浸渍提拉法制备 ;随着前驱物中聚乙二醇加入量的增加 ,多孔 Ti O2 薄膜表面的羟基含量也增加 ,薄膜表面的亲水性增强 ,水与薄膜表面的接触角下降为 0°.该亲水性多孔 Ti O2 薄膜自洁净玻璃具有明显的自洁净和易清洗功能 .紫外 -可见光透过光谱分析表明 ,随着 Ti O2 薄膜中孔径的增大 ,光的散射增强 ,透光率减小 .该 Ti O2 镀膜玻璃对于紫外线具有吸收作用 .甲基橙水溶液的光催化降解实验表明 ,在 Ti O2 薄膜中引入适当大小的微孔可显著增强薄膜的光催化活性 ,但当孔径接近 40 0 nm时 ,薄膜的光催化活性减弱 .

Synthesis of bionic-macro/microporous MgO-modified TiO_2 for enhanced CO_2 photoreduction into hydrocarbon fuels

The stems of water convolvulus were employed as biotemplates for the replication of their optimized 3D hierarchical architecture to synthesize porous MgO-modified TiO2 . The photocatalytic reduction of CO2 with H2O vapor into hydrocarbon fuel was studied with these MgO-TiO2 nanostructures as the photocatalysts with the benefits of improved CO2 adsorption and activation through incorporated MgO. Various factors involving CO2 adsorption capacity, migration of charge carriers to the surface, and the number of activity sites, which depend on the amount of added MgO, determine the photocatalytic conversion efficiency.

Review on porous nanomaterials for adsorption and photocatalytic conversion of CO_2

Photocatalytic conversion of“greenhouse gas”CO2is considered to be one of the most effective ways to alleviate current energy and environmental problems without additional energy consumption and pollutant emission.The performance of many traditional semiconductor photocatalysts is not efficient enough to satisfy the requirements of practical applications because of their limited specific surface area and low CO2adsorption capacity.Therefore,the exploration of photocatalysts with high CO2uptake is significant in the field of CO2conversion.Recently the porous materials appeared to be a kind of superior candidate for enriching the CO2molecules on the surface of photocatalysts for catalytic conversion.This paper first summarizes the advances in the development of nanoporous adsorbents for CO2capture.Three main classes of porous materials are considered:inorganic porous materials,metal organic frameworks,and microporous organic polymers.Based on systematic research on CO2uptake,we then highlight the recent progress in these porous‐material‐based photocatalysts for CO2conversion.Benefiting from the improved CO2uptake capacity,the porous‐material‐based photocatalysts exhibited remarkably enhanced efficiency in the reduction of CO2to chemical fuels,such as CO,CH4,and CH3OH.Based on reported recent achievements,we predict a trend of development in multifunctional materials with both high adsorption capability and photocatalytic performance for CO2utilization.

Cooling of Superheated Refrigerants Flowing inside Tubes Filled with Porous Media： Study of Heat Transfer and Pressure Drop, Carbon Dioxide Case Study

In this work an experimental study combined with an analytical investigation for cooling superheated Carbon Dioxide （CO2） gas were carried out. This work is intended to be part of the super critical Gustav Lorentzen refrigeration cycle of CO2. Experimental and analytical works concentrated on heat transfer and pressure drop for single phase flow during gas cooling inside tubes filled with porous media. Analytical empirical correlations were formulated for the coefficient of convectional heat transfer and for the pressure drop. A comparison between experimental results and that obtained by developed correlations were carried out, and a comparison between these results and literature published ones were carried out too. The results of this research showed that for cooling process the proposed correlations were proved to be acceptably accurate for pressure drop with difference from experimental results of 2%, while for convective heat transfer the difference from experimental results reached about 3%. More than 90% agreement with literature results was obtained. This work can enhance the calculations of heat flux and pressure drop of gases flow inside porous media filled tubes, and can help in the design procedure of heat exchangers and cooling processes.

Selective electroreduction of carbon dioxide to formic acid on electrodeposited SnO_2@N-doped porous carbon catalysts

Electrocatalytic reduction of CO_2 is a promising route for energy storage and utilization. Herein we synthesized SnO_2 nanosheets and supported them on N-doped porous carbon (N-PC) by electrodeposition for the first time. The SnO_2 and N-PC in the SnO_2@N-PC composites had exellent synergistic effect for electrocatalytic reduction of CO_2 to HCOOH. The Faradaic efficiency of HCOOH could be as high as 94.1% with a current density of 28.4 mA cm-2 in ionic liquid-MeCN system. The reaction mechanism was proposed on the basis of some control experiments. This work opens a new way to prepare composite electrode for electrochemical reduction of CO_2.

Room-temperature liquid metal synthesis of nanoporous copper-indium heterostructures for efficient carbon dioxide reduction to syngas

Nanoporous metals show promising performances in electrochemical catalysis.In this paper,we report a self-supporting bimetallic porous heterogeneous indium/copper structure synthesized with a eutectic gallium-indium(EGaIn)material on a copper substrate.This nanoporous copper-indium heterostructure catalyst exhibits excellent performance in the reduction of carbon dioxide to syngas.The ratio of H_(2)/CO is tunable from 0.47 to 2.0 by changing working potentials.The catalyst is highly stable,showing 96%maintenance of the current density after a 70-h continuous test.Density functional theory calculations reveal that the indium/copper interface induces charge redistribution within the copper surface,leading to the formation of two distinct active sites,namely,Cu^(δ)and Cu0,and enabling a high-performance generation of CO and H_(2).This work provides a new strategy for obtaining self-supporting nanoporous metal electrode catalysts.

Pyrene-based covalent triazine framework towards high-performance sensing and photocatalysis applications

Porous organic polymers(POPs)are an emerging class of porous materials,having many promising applications in a variety of areas.Among them,covalent triazine frameworks(CTFs)featuring conjugated and porous structures can be well applied in optoelectronics.To achieve high optoelectronic performance,usually the design and synthesis of CTFs based on appropriate building blocks is critical.Here we report the synthesis of two fluorescent CTFs based on typical fluorescent building blocks,in which CTF-Py constructed from a pyrene(Py)building block was reported for the first time,showing prospective applications in the sensing of nitroaromatics with high sensitivity,and photocatalytic water splitting and carbon dioxide reduction with high performance in comparison with other porous organic materials.

In-situ observation for formation and dissociation of carbon dioxide hydrate in porous media by magnetic resonance imaging

The study of formation and dissociation of CO 2 hydrate in porous media was characterized by magnetic resonance imaging (MRI) system in in situ conditions. This work simulated porous media by using glass beads of uniform size. The growth and dissociation habit of CO2 hydrate was observed under different temperature and pressure conditions. The induction time and the hydrate saturation during the growth and dissociation process in different sizes of porous media were obtained by using the MRI signal intensity. The results indicate that hydrate growth rate and the induction time are affected by the size of porous media, pressure, and degree of supercooling. There are three hydrate growth stages, i.e., initial growth stage, rapid growth stage and steady stage. In this study,the CO2 hydrate forms preferentially at the surface of vessel and then gradually grows inward. The hydrate tends to cement the glass beads together and occupies the pore gradually. As the hydrate decomposes gradually, the dissociation rate increases to the maximum and then decreases to zero.

Microporous polymer based on hexaazatriphenylene-fused triptycene for CO2 capture and conversion

Chemical conversion of carbon dioxide(CO2)to value-added useful chemicals like cyclic carbonates represents one potential solution to climate warming.Here,a kind of porous organic polymer(HAT-TP)with large surface area and excellent carbon dioxide uptake capacity is prepared via a condensation reaction to introduce hexaazatriphenylene(HAT)units into triptycene(TP)-based microporous polymer.HAT-TP can coordinate with zinc ions,and the resulting polymer(Zn/HAT-TP)can be utilized as an efficient recyclable catalyst for chemical conversion of CO2 into cyclic carbonates with epoxides.