•Based on phosphosilicate sol and sulfonated poly(ether ether ketone) polymer, the composite membranes are prepared.•The composite membranes exhibit satisfactory mechanical properties even with 50% inorganic components of their weight.•The composite membrane shows a conductivity of 1.1 mS cm−1 at 250 °C.Phosphosilicate sol/sulfonated poly(ether ether ketone) (PSi/SPEEK) composite membranes are fabricated by a simple mechanical mixing process. SPEEK provided the PSi/SPEEK membranes with satisfactory mechanical properties even when inorganic components made up 50% of their weight. Membrane proton conductivity was evaluated in the 180–250 °C range under ambient conditions of humidification from 100 °C water vapor and without humidity. A proton conductivity of 1.1 mS cm−1 was reached from the composite membrane 5P5Si5/5SPEEK at 250 °C with 100 °C water vapor, because of its improved hygroscopicity and functional groups. The conductivity of the 5P5Si5/5SPEEK membrane in ambient conditions with humidity from 100 °C water vapor was higher than in ambient conditions without humidity. This disparity was especially apparent above 200 °C.

•We fabricate an electrolyte membrane for intermediate temperature fuel cells.•The electrolyte membrane shows excellent mechanical and thermal properties.•The conductivity of the membrane is above 10−3 S cm−1 in the range of 130–230 °C.Solid acids are considered as a promising electrolyte for intermediate temperature fuel cells (ITFCs), but their application is hindered by their inherent shortcomings, including poor mechanical properties, limited chemical stability, low proton conductivity at low temperature and narrow high-conductivity temperature range. Despite much work devoted to addressing these shortcomings, none of them can tackle these issues simultaneously. In view of this, we reported a composite electrolyte membrane based on CsH2PO4, sulfonated poly(ether ether ketone) and phosphosilicate sol. The electrolyte membrane was fabricated by using a simple sol–gel process combined with mechanical ball-milling. The prepared electrolyte membrane exhibits excellent mechanical performance with a tensile strength of 23.5 MPa, despite an inorganics content of 70 wt%. The electrolyte membrane can keep intact even if it is heated to 260 °C. The measurement of proton conductivity shows that the electrolyte membrane can maintain a high conductivity of above 10−3 S cm−1 over a broad temperature range of 130–230 °C under ambient condition without humidifying. The successful fabrication of the electrolyte membrane not only provides a promising membrane for ITFCs, but also opens fresh insights for the development of electrolytes with superior comprehensive performance and the application of solid acids in ITFCs.

•The composite membranes based on phosphosilicate sol and sulfonated poly(ether ether ketone) are fabricated.•The composite membranes show improved proton conductivity, thermal and dimensional stability.•A maximum of the proton conductivity of 0.138 S cm−1 is obtained.•A fuel cell using the composite membrane exhibits a peak power density of 449.9 mW cm−2.The phosphosilicate sol/sulfonated poly(ether ether ketone) (SPEEK) composite membranes are fabricated by using a simple mechanical mixing process. The performance of the composite membranes is investigated, including their morphology, thermal and mechanical properties, water adsorption and swelling ratio, proton conductivity and fuel cell performance. The composite membranes obtain the advantages of both components while avert their disadvantages, showing excellent comprehensive performance. The utilization of SPEEK endows the composite membranes with good mechanical properties even if the proportion of inorganic components in the membranes is as high as 40 wt.%. The incorporation of phosphosilicate sol not only enhances the dimensional and thermal stability of the composite membranes, but also improves their conductivity significantly. A maximum of proton conductivity of 0.138 S cm−1, higher than that of Nafion 212 membrane (0.124 S cm−1), is obtained from the composite membrane 6SPEEK/4(P–Si) under the conditions of 70 °C and 95% relative humidity, owing to its enhanced hygroscopicity and functional groups. Besides, a single fuel cell equipped with the composite membrane 7SPEEK/3(P–Si) releases a peak power density of 449.9 mW cm−2 at 60 °C, higher than that of cells equipped with SPEEK and Nafion 212 membrane measured under the same conditions.

•H3PO4 is used as the template agent in silica antireflective films.•The transmittance of antireflective films is improved dramatically owing to the addition of H3PO4.•The transmittance of films rises first and then decreases slightly with the decrease in H3PO4 concentration.In this work, the feasibility is investigated and confirmed that H3PO4 is used as pore-forming agent in silica antireflective film. The films are prepared by sol–gel method and spinning-coating technique and studied by field-emission scanning electron microscopy (FE-SEM), visible spectroscopy and ellipsometer. The impact of H3PO4 concentration on transmittance is also examined. Transmittance spectra show that silica films feature a marked increase of substrate transmittance almost at all measured wavelengths (325–1000 nm) owing to the addition of H3PO4. With the decrease of H3PO4 concentration, films transmittance will rise first and then decrease slightly. And with an increase of 4.1%, a maximum light transmittance of 95.01% is obtained, which is comparable to some other antireflective films using organic templates.

•A direct methanol fuel cell with a composite membrane is prepared.•The methanol permeability of the composite membrane is lower than that of Nafion®.•The direct methanol fuel cell releases a peak power density of 73.1 mW cm−2.A direct methanol fuel cell (DMFC) with a proton-conducting composite membrane, which is synthesized from Nafion®/phosphosilicate (NPS) glass and sulfonated poly(ether ether ketone) (SPEEK) polymer, is prepared, and its performance is evaluated at different cell temperatures, methanol flow rates, and oxygen backpressures. The methanol permeability of the NPS/SPEEK composite membrane is determined to be 7.5 × 10−7 cm2 s−1. The developed DMFC releases a peak power density of 73.1 mW cm−2 at a cell temperature of 85 °C.

Based on Nafion®/phosphosilicate (NPS) glass and sulfonated poly(ether ether ketone) (SPEEK) polymer, proton-conducting NPS/SPEEK composite membranes are prepared by a simple mechanical ball-milling approach. The chemical structure, morphology, pore structure, and proton conductivity of the NPS/SPEEK composite membranes are investigated. Due to the incorporation of the SPEEK polymer, the obtained composite membranes exhibit sufficient flexibility and remarkably reduced pore volume compared to fragile and highly porous NPS glass. On the other hand, the NPS/SPEEK composite membranes exhibit improved proton conductivities compared with pure SPEEK. Specifically, the composite membranes display quite high proton conductivities of above 10−3 S cm−1 in the temperature range from 30 to 80 °C at 90% relative humidity, while pure SPEEK shows moderate proton conductivities of 10−3–10−4 S cm−1 under the same conditions. For a single H2/O2 fuel cell equipped with the NPS/SPEEK composite membrane, a peak power density of 322 mW cm−2 is obtained at 65 °C.Graphical abstractHighlights► Based on Nafion®/phosphosilicate glass and sulfonated poly(ether ether ketone) polymer, the composite membranes are prepared by a simple mechanical ball-milling approach. ► The composite membranes exhibit sufficient flexibility and remarkably reduced pore volume. ► The composite membranes display quite high proton conductivities of above 10−3 S cm−1. ► A single H2/O2 fuel cell equipped with the composite membrane releases a peak power density of 322 mW cm−2.

H2/O2 fuel cells equipped with proton-conducting Nafion®/phosphosilicate (NPS) glass membranes, which are prepared from phosphosilicate glass and a perfluorosulfonic acid polymer, are characterized, and their performances are improved step by step by using Nafion® resin as an adhesive, increasing operation temperature, adopting a thin-film pressure sensor, and reducing glass membrane thickness. Finally, the fuel cell with a 500 μm thick NPS glass membrane releases a peak power density of 207 mW cm−2 at 70 °C.Graphical abstractHighlights► H2/O2 fuel cells equipped with proton-conducting Nafion®/phosphosilicate (NPS) glass membranes, which are prepared from phosphosilicate glass and a perfluorosulfonic acid polymer, are characterized. ► The fuel cell performances are improved step by step by using Nafion® resin as an adhesive, increasing operation temperature, adopting a thin-film pressure sensor, and reducing glass membrane thickness. ► The fuel cell with a 500 μm thick NPS glass membrane releases a peak power density of 207 mW cm−2 at 70 °C.

An ultra-thin, free-standing proton-conductive membrane of Nafion®/Phosphosilicate/Nafion® (NPN) with a sandwich structure has been prepared. The NPN membrane of thickness 960 nm shows extremely low methanol permeability of 1 × 10−8 cm2 s−1, and area specific resistance (ASR) smaller than 0.2 Ω cm2.

An integrated, crack-free glass monolith is prepared via a modified sol–gel approach. It has an accessible network of channels consisting of anisotropic pores of widths ca. 20–50 nm and lengths ca. 100–250 nm. The glass monolith exhibits a transparency change based on humidity, which is utilized as a basis for optical humidity measurements. On the other hand, the glass monolith shows high proton conduction in humid atmosphere, and its proton conductivity reaches a value of 0.12 S cm−1 at 30 °C and 80% relative humidity.Graphical abstractResearch highlights▶ Optical humidity sensing, proton-conducting sol-gel glass monolith is prepared. ▶ The glass monolith exhibits proton conductivities of of ca. 10−1 S cm−1. ▶ The transmittance of the glass monolith changes with humidity. ▶ This glass monolith is utilized for optical humidity measurements.

A proton-conducting glass membrane based on porous phosphosilicate and perfluorosulfonic acid polymer was prepared via a modified sol–gel approach. The morphology, pore structure, water uptake property, proton conductivity and fuel cell performance of the membrane were investigated in this work. The hybrid glass membrane showed extremely high proton conductivity of 0.1 S cm−1 in humid atmosphere. In the H2/O2 fuel cell measurement, an open circuit potential (OCV) of 0.94 V and a maximum output power density of 42.6 mW cm−2 was obtained at 25 °C.

Porous silica xerogels are prepared by sol–gel syntheses templated with Brij56 or F127 surfactants. The porous properties of the obtained silica xerogels are characterized by N2 sorption measurements. The F127 surfactant-templated silica xerogel exhibits a pore size distribution peaking at 4.2 nm in the mesopore region, a pore surface are of 510 m2 g−1, and a pore volume of 0.545 mL g−1, while the Brij56 surfactant-templated silica xerogel has a bimodal pore size distribution with maxima at 0.65 nm and near 2 nm in the micropore region, a pore surface area of 739 m2 g−1, and a pore volume of 0.354 mL g−1. Their water vapor sorption properties are evaluated under various relative humidity at 25 and 35 °C using gravimetric technique. The results show that the F127 surfactant-templated xerogel with larger pore size and higher volume could absorb a large amount of water molecules at high humidity and efficiently release it at low humidity, such that it has a large water adsorption–desorption capacity, whilst the Brij56 surfactant-templated xerogel with smaller pore size and larger pore surface area could maintain a high water content even at low humidity levels.Graphical abstractResearch highlights► Porous silica xerogels have been prepared by sol-gel synthesis templated with oligomeric Brij56 and triblock copolymer F127 non-ionic surfactants. ► The F127-templated silica xerogel has a preponderant mesoporosity, while the Brij56-templated silica xerogel has a high fraction of microporosity. ► The F127 surfactant-templated xerogel could absorb a large amount of water molecules at high humidity, and efficiently release it at low humidity. ► The Brij56 surfactant-templated xerogel could maintain a high water content level even at a low humidity.

We report monolithic and transparent phosphosilicate membranes (PSMs) for high proton conduction. The membrane material was derived from the sol–gel precursors of tetraethoxysilane (TEOS) and orthophosphoric acid (H3PO4), which were subjected to hydrothermal treatment at 150 °C for 30 h. The obtained PSMs exhibited proton conductivities of up to 10−1 S cm−1, which is comparable to those of available commercial membranes, such as a Nafion® membrane. The unique hydrothermal treatment that we employed and the utilization of H3PO4 as raw material are believed to be responsible for the high proton conduction of the resulting PSMs.Graphical abstractResearch highlights► We have developed monolithic and transparent phosphosilicate membranes (PSMs) showing high proton conduction. The membrane material was derived from the sol–gel precursors of tetraethoxysilane (TEOS) and orthophosphoric acid (H3PO4), which were subjected to a hydrothermal treatment at 150 °C. ► The developed PSMs exhibit proton conductivities of ca. 10−1 S cm−1, and reach a surprisingly high proton conductivity of 0.21 S cm−1 at 90 °C under 70% relative humidity, which is about twice as high as that of a Nafion membrane. ► It is suggested that the unique hydrothermal treatment that we employed and the utilization of H3PO4 as a raw material are responsible for the high proton conduction of the obtained PSMs. ► Such phosphosilicate membranes with high proton conductivity and low cost are expected to be promising for use in fuel cells and sensors, etc.

•A mesoporous silica membrane was fabricated on a macroporous alumina support.•A heat-sealing treatment procedure is introduced.•Air-cushion can prevent the infiltration of the precursor solution into pores.We report a unique technique for fabricating a uniform and crack-free surfactant-templated silica membrane on a porous alumina support. The porous alumina support was first subjected to a heat-sealing treatment, and then a mesoporous silica membrane derived from a surfactant template was deposited thereon by sol–gel processing. The surface topography of the silica membrane has been characterized. With the aid of the sealing procedure, an air-cushion was formed to provide sufficient additional supporting force to support the precursor film and prevent permeation of the precursor into the pores. The sol–gel deposition on the porous alumina support formed a uniform, crack-free silica membrane.