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TiO2/SiO2-Based nanocomposites with highly porous structures have received increasing attention due to their excellent photocatalytic activity. In this work, a TiO2/SiO2/Ag ternary composite aerogel with enhanced visible-light photocatalytic activity has been successfully synthesized through a facile sol–gel method combined with a supercritical drying technique. The specific surface area and pore structure of TiO2/SiO2/Ag aerogel could be controlled by adjusting the Si content. The TiO2/SiO2/Ag aerogel with pore size of 9.2 nm achieved the maximum adsorption capacity of oxytetracycline. The presence of SiO2 in TiO2/SiO2/Ag improved the compression strength of the aerogel and thus achieved long-term stability in photocatalysis. Furthermore, the addition of Ag particles in TiO2/SiO2/Ag effectively decreased the recombination of photo-electrons and holes. The photocatalytic degradation rates of oxytetracycline over the TiO2/SiO2/Ag aerogel with a mole ratio of Ag : Si : Ti = 0.1 : 10 : 4 were 3.1 and 2.3 times those over P25 and a TiO2/SiO2 aerogel. The enhanced photocatalytic performance of the TiO2/SiO2/Ag aerogel is attributed to the large specific surface area, 3-D porous structure, high electrical conductivity and compression strength of this novel composite aerogel. [ABSTRACT FROM AUTHOR]

A novel Z‐scheme polyimide (PI)/AgBr@Ag aerogel photocatalyst has been successfully synthesized by combining an in situ precipitation method and a supercritical drying method. The as‐prepared PI/AgBr@Ag‐50 (50 wt % AgBr@Ag in PI/AgBr@Ag) aerogel photocatalyst exhibited excellent photocatalytic activity for oxytetracycline degradation with a rate constant of 0.025 min−1, which was 6.9 and 2.6 times higher than that of the PI aerogel or the AgBr@Ag nanoparticles, respectively. More significantly, the PI/AgBr@Ag‐50 aerogel photocatalyst showed stable cycling, which could be attributed to the high mechanical strength and 3D network of the PI aerogel. The introduction of AgBr@Ag on PI with a heterojunction structure efficiently promoted the separation of electron–hole pairs by a Z‐scheme mechanism. The reduced metallic Ag nanoparticles were found to function as centers for the transfer of electrons from AgBr to PI. This work has revealed a new application for the aerogel PI/AgBr@Ag photocatalyst in environmental protection. Two is better than one: AgBr@Ag nanoparticles were uniformly dispersed on a polyimide (PI) aerogel, and the resultant Z‐scheme PI/AgBr@Ag composite aerogel exhibited excellent photocatalytic activity for oxytetracycline (OTC) degradation under visible light, which can be attributed to the synergy between the AgBr@Ag plasmonic photocatalyst and the PI semiconductor photocatalyst (see figure). [ABSTRACT FROM AUTHOR]

• PI/Ag aerogel photocatalysts were designed by the sol-gel method and ethanol supercritical drying technique, which can induce the formation of Ag C bonds and Ag nanoparticles in PI/Ag aerogels. • The average rate of H 2 production is 166.1 μmol h−1 g−1 for PI/Ag-1 aerogel, which is ca. 8 times as much as that of PI aerogel. • Photocatalytic activity for H 2 production over PI/Ag aerogel is improved much due to the enhanced carrier mobility efficiency, optical absorption and large specific area of the photocatalyst. As one kind of promising photocatalyst, polyimide (PI) still suffers from poor light absorption, low charge transfer efficiency and small specific surface area. Herein, PI/Ag aerogel photocatalysts were designed by the sol-gel method and ethanol supercritical drying technique. As expected, Ag element in PI/Ag aerogel is in two forms, one is introduced into the imide ring of PI in the form of Ag C bond, and another is the dopant Ag atoms. The former kind of Ag element can weaken the planar hydrogen bonding and improve the charge transfer efficiency, and the latter can form LSPR effect and promote the photoelectron-holes separation. Apart from that, the high specific surface area of the aerogel photocatalyst also favors the photocatalysis. All these effects boost the photocatalytic activity of the PI/Ag aerogel photocatalysts. The average rate of H 2 production is up to 166.1 μmol h−1 g−1 for PI/Ag-1 aerogel, which is ca. 8 times as much as that of PI aerogel. The work supplies an efficient approach for constructing effective aerogel photocatalysts for H 2 production. [ABSTRACT FROM AUTHOR]

Abstract: Resorcinol–formaldehyde/alumina composite (RF/Al2O3) gels were initially prepared by using sol–gel techniques, and then dried to aerogels with supercritical fluid CO2. After thermal treatment in argon atmosphere, RF/Al2O3 aerogels were successfully converted to monolithic carbon/alumina composite (C/Al2O3) aerogels. The samples were characterized by BET, SEM, TEM and XRD, and the compressive strengths were measured. The experimental results showed that the C/Al2O3 aerogels exhibited an interpenetrating framework with high mesoporosity. The as-synthesized C/Al2O3 aerogels consisted of spherical carbon particles and alumina (fibrous or columnar), which had high BET surface area (576–831m2/g) and showed high compressive strength (5.4–9.1MPa) and Young’s modulus (286.95–476.71MPa). These novel C/Al2O3 aerogels could possibly be used as thermal isolates, catalysts and adsorbents. [Copyright &y& Elsevier]