•Erecting a comprehensive emergy frame evaluating bio-hydrogen-tech industrialization.•Realizing the numerical calculation of the comprehensive efficiency evaluation model.•Distinguishing human-capital, policy-aid and resource-structure in the business case.•Fermentative-organic-wastewater bio-hydrogen is more sustainable.Focusing on the incompatible measurement of the environment property, resources property and economy property, the article aims to make a generalized environment-resource-economy analysis of the processes and to present an overview of different biohydrogen production technologies from the standpoint of the mass production and the whole commercialization chain. One part of the model is the emergy comprehensive efficiency index calculation model, the other is the ternary diagram of structure coefficient for emergy input. The model is used to the organic wastewater of the biohydrogen industrialization demonstration project, and then compared with other biohydrogen and typical renewable energy production technologies. The outputs indicate that the industrialization efficiency of biohydrogen production is available. After the application case of demonstration project, the exploratory work enlightens the similar literature from several aspects. Firstly, the efficiency evaluation model supplies a scientific judgment foundation stone for future laboratory research. Secondly, it provides an alternative theoretical logic to optimize the operation and decision-making of the industrialization and commercialization of the new technologies. Thirdly, it provides a new perspective and quantitative calculation method to effectively integrate that the components comprehensive efficiency of biohydrogen technology change with the different technology processes.

The commercialization of solid oxide fuel cell (SOFC) needs the development of functional materials for intermediate-to-low temperature (400–700 °C, ILT) operation. Recently, we have successfully developed new electrolyte materials for ILT-SOFCs, including Ce0.8Sm0.2O1.9 (SDC), BaCe0.8Sm0.2O2.9 (BCSO) and SDC-carbonate composites. Compared with the state-of-the-art yttria-stabilized zirconia (YSZ), these materials exhibit much higher ionic conductivity at ILT range. Especially, SDC-carbonate composites show an ionic conductivity of 10−2 to 1 Scm−1 between 400 and 600 °C in fuel cell environment. Some new cathode materials were investigated for above electrolyte materials and showed promising performance. Alternative anode materials were developed to directly utilize alcohol fuels. A dry-pressing and co-firing process was employed to fabricate thin SDC and BCSO electrolyte membranes as well as thick SDC-carbonate composite electrolyte with acceptable density on anode substrate. Many efforts have also been made on fabrication of larger-size planar cells and exploitation of reliable sealing materials.Highlights► Advances in the development of ILT-SOFC materials in our lab were reviewed. ► Compatible cathode materials were developed for IT-SOFCs based on SDC electrolyte. ► Thin-film BSCO electrolyte IT-SOFC was fabricated and demonstrated stable output. ► SDC-carbonate composite electrolytes exhibited co-ion or pure proton conduction. ► The composite electrolyte LT-SOFCs showed high performance and good stability.

In this paper anode support was fabricated by tape casting method using SDC-50 wt.% NiO slurry, then printed the Ce0.8Sm0.2O1.9 (SDC) electrolyte on the green piece which is cut out from the dried slurry piece. After at 90 °C drying for 14 h and co-sintered at 1350 °C for 10 h, get the Φ70 mm anode support and electrolyte planar bilayer. Based on the observation of photos and scanning electron microscopy (SEM) indicated that bilayer owns the flat anode support substrate, and the highly dense, crack free electrolyte film which is 12 μm in thickness. Small disks which were cut out from the Φ70 mm bilayer structure electrochemically were examined in a single button-cell mode incorporating a SDC-60 wt.% La0.5Sr0.5Co0.8Fe0.2O3 composite cathode. The single cell was tested at 450 °C∼600 °C, an open-circuit voltage (OCV) of 0.94 V and the maximum power density of 797 mV cm−2 achieved with dry hydrogen as fuel gas and air as oxidant gas at 600 °C.Highlights► Anode support was fabricated by tape casting method using SDC-50wt.%NiO slurry. ► Anode film is about 12 μm in thickness. Cathode is Ba0.5Sr0.5Co0.8Fe0.2O3/SDC. ► The single cell’ achieved 0.32 A·cm−2·at 0.6 V with hydrogen and air at 600 °C.

In this study, a ceria-based composite electrolyte was investigated for intermediate-temperature solid oxide fuel cells (SOFCs) based on SDC–25 wt.% K2CO3. Sodium carbonate co-precipitation process by which SDC powder was adopted and sound cubic fluorite structure was formed after SDC powders were sintered at 750 °C for 3 h. The crystallite size of the particle was 21 nm in diameter as calculated from data obtained through X-ray diffraction. The conductivity of the composite electrolyte proposed in this study was much higher than that of pure SDC at the comparable temperature of 550–700 °C. The transition of the ionic conductivity occurred at 650 °C. Based on this type of composite electrolyte, single cell with the electrolyte thickness of 0.3 mm were fabricated using dry pressing, with nickel oxide adopted as anode and SSC as cathode. The single cell was then tested at 550–700 °C on home-made equipment in this study, using hydrogen/air. The maximum power density and open circuit voltage (OCV) achieved 600 mW cm−2 and 1.05 V at 700 °C, respectively.

The SrTixCo1−xO3−δ (STC, x = 0.05, 0.1, 0.15, 0.2) perovskite-type oxides synthesized by the polymerized complex (PC) method have been investigated as cathode materials for low-temperature solid oxide fuel cells (SOFCs) with composite electrolyte for the first time. Thermogravimetry–differential thermal analysis (TG–DTA) shows the crystallization of SrTi0.1Co0.9O3−δ occurs at 780 °C. The oxides have been stabilized to be a cubic perovskite phase after the B-site is doped with Ti ion. The maximum power density reaches as high as 613 mW cm−2 at 600 °C for SOFC with SrTi0.2Co0.8O3−δ cathode. The maximum power densities increase with the increasing Ti content in the cathode, which can be attributed to the enhancement of conductivity and electrocatalytic activity. The stability of the fuel cell with SrTi0.1Co0.9O3−δ cathode has been examined for 18 h at 600 °C. Only a slight decline in the cell performance can be observed with increasing time. The high performance cathodes together with the low-cost fabrication technology are highly encouraging for development of low-temperature SOFCs.

Sm0.2Ce0.8O1.9 (SDC)/Na2CO3 nanocomposite synthesized by the co-precipitation process has been investigated for the potential electrolyte application in low-temperature solid oxide fuel cells (SOFCs). The conduction mechanism of the SDC/Na2CO3 nanocomposite has been studied. The performance of 20 mW cm−2 at 490 °C for fuel cell using Na2CO3 as electrolyte has been obtained and the proton conduction mechanism has been proposed. This communication demonstrates the feasibility of direct utilization of methanol in low-temperature SOFCs with the SDC/Na2CO3 nanocomposite electrolyte. A fairly high peak power density of 512 mW cm−2 at 550 °C for fuel cell fueled by methanol has been achieved. Thermodynamical equilibrium composition for the mixture of steam/methanol has been calculated, and no presence of C is predicted over the entire temperature range. The long-term stability test of open circuit voltage (OCV) indicates the SDC/Na2CO3 nanocomposite electrolyte can keep stable and no visual carbon deposition has been observed over the anode surface.

Currently, the increasing price of oil and the possibility of global energy crisis demand for substitutive energy to replace fossil energy. Many kinds of renewable energy have been considered, such as hydrogen, solar energy, and wind energy. Many countries including China have their own plan to support the research of hydrogen, because of its premier features. But, at present, the cost of hydrogen energy production, storage and transportation process is higher than that of fossil energy and its commercialization progress is slow. Life cycle cost analysis (LCCA) was used in this paper to evaluate the cost of hydrogen energy throughout the life cycle focused on the stratagem selection, to demonstrate the costs of every step and to discuss their relationship. Finally, the minimum cost program is as follows: natural gas steam reforming – high-pressure hydrogen bottles transported by car to hydrogen filling stations – hydrogen internal-combustion engines.

Perovskite-type La1−xSrxNiyFe1−yO3−δ (x = 0.3, 0.4, 0.5, 0.6, y = 0.2; x = 0.3, y = 0.2, 0.3, 0.4) oxides have been synthesized and employed as cathodes for low-temperature solid oxide fuel cells (SOFCs) with composite electrolyte. The segregation of La2NiO4±δ is observed to increase with the increasing Sr2+ incorporation content according to X-ray diffraction (XRD) results. The as-prepared powders appear porous foam-like agglomeration with particle size less than 1 μm. Maximum power densities yield as high as 725 mW cm−2 and 671 mW cm−2 at 600 °C for fuel cells with the LSNF4628 and LSNF7337 composite cathodes. The maximum power densities continuously increase with the increasing Sr2+ content in LSNF cathodes, which can be mainly ascribed to the possible charge compensating mechanism. The maximum power densities first increase with the Ni ion incorporation content up to y = 0.3 due to the increased oxygen vacancy, ionic conductivity and oxygen permeability. Further increase in Ni ion content results in a further lowering of fuel cell performance, which can be explained by the association of oxygen vacancies and divalent B-site cations in the cathode.

Nanocrystalline Ce0.8Sm0.2O1.9 (SDC) has been synthesized by a combined EDTA–citrate complexing sol–gel process for low temperature solid oxide fuel cells (SOFCs) based on composite electrolyte. A range of techniques including X-ray diffraction (XRD), and electron microscopy (SEM and TEM) have been employed to characterize the SDC and the composite electrolyte. The influence of pH values and citric acid-to-metal ions ratios (C/M) on lattice constant, crystallite size and conductivity has been investigated. Composite electrolyte consisting of SDC derived from different synthesis conditions and binary carbonates (Li2CO3–Na2CO3) has been prepared and conduction mechanism is discussed. Water was observed on both anode and cathode side during the fuel cell operation, indicating the composite electrolyte is co-ionic conductor possessing H+ and O2− conduction. The variation of composite electrolyte conductivity and fuel cell power output with different synthesis conditions was in accordance with that of the SDC originated from different precursors, demonstrating O2− conduction is predominant in the conduction process. A maximum power density of 817 mW cm−2 at 600 °C and 605 mW cm−2 at 500 °C was achieved for fuel cell based on composite electrolyte.

Lanthanum nickelate based oxides, including La2NiO4+δ (LN), La2Ni0.8Co0.2O4+δ (LNC82) and La2Ni0.8Fe0.2O4+δ (LNF82), were investigated as cathodes for intermediate temperature fuel cells with samaria doped ceria (SDC)–carbonate composite electrolytes. These oxides were synthesized by glycine–nitrate process and characterized by XRD and SEM, showing that all samples annealed at 800 °C for 2 h exhibit a K2NiF4 phase and a foam-like structure. The electrochemical properties of these cathodes were evaluated by fabricating and testing fuel cells with two kinds of composite electrolytes, SDC-20 wt.% (0.53Li/0.47Na)2CO3 and SDC-30 wt.% (0.67Li/0.33Na)2CO3, referred to as SDC(53L47N)20 and SDC(67L33N)30, respectively. Among these three cathodes, LNC82 shows the best cell performances at 500–600 °C. Moreover, fuel cells with SDC(67L33N)30 composite electrolyte present much higher power output than those with SDC(53L47N)20 composite electrolyte. It reveals that cobalt doping greatly enhances the electrochemical property of lanthanum nickelate, and such cathodes are more compatible with the SDC(67L33N)30 composite electrolyte.

Samaria-doped ceria (SDC)/carbonate composite electrolytes were developed for low-temperature solid oxide fuel cells (SOFCs). SDC powders were prepared by oxalate co-precipitation method and used as the matrix phase. Binary alkaline carbonates were selected as the second phase, including (Li–Na)2CO3, (Li–K)2CO3 and (Na–K)2CO3. AC conductivity measurements showed that the conductivities in air atmosphere depended on the salt composition. A sharp conductivity jump appeared at 475 °C and 450 °C for SDC/(Li–Na)2CO3 and SDC/(Li–K)2CO3, respectively. However, the conductivities of SDC/(Na–K)2CO3 increase linearly with temperature. Single cells based on above composite electrolytes were fabricated by dry-pressing and tested in hydrogen/air at 500–600 °C. A maximum power density of 600, 550 and 550 mW cm−2 at 600 °C was achieved with SDC/(Li–Na)2CO3, SDC/(Li–K)2CO3 and SDC/(Na–K)2CO3 composite electrolyte, respectively, which we attribute to high ionic conductivities of these composite electrolytes in fuel cell atmosphere. We discuss the conduction mechanisms of SDC/carbonate composite electrolytes in different atmospheres according to defect chemistry theory.

A ceria-based composite electrolyte with the composition of Ce0.8Sm0.2O1.9 (SDC)–30 wt.% (2Li2CO3:1Na2CO3) is developed for intermediate temperature fuel cells (ITFCs). Two kinds of SDC powders are used to prepare the composite electrolytes, which are synthesized by oxalate coprecipitation process and glycine–nitrate process, respectively, and denoted as SDC(OCP) and SDC(GNP). Based on each composite electrolyte, two single cells with the electrolyte thickness of 0.3 and 0.5 mm are fabricated by dry-pressing technique, using nickel oxide as anode and lithiated nickel oxide as cathode, respectively. With H2 as fuel and air as oxidant, all the four cells exhibit excellent performances at 400–600 °C, which can be attributed to the highly ionic conducting electrolyte and the compatible electrodes. The cell performance is influenced by the SDC morphology and the electrolyte thickness. More interestingly, such composite electrolytes are found to be proton conductors at intermediate temperature range for the first time since almost all water is observed at the cathode side during fuel cell operation for all cases. The unusual transport property, excellent cell performance and potential low cost make this kind of composite material a good candidate electrolyte for future cost-effective ITFCs.

Polyethylene glycol (PEG) with different average molecular weight (400, 2000, 6000, 20 000) was used as a templating reagent to synthesize PEG-modified TiO2TiO2 photocatalyst by sol–gel method. This study revealed that PEG molecules of appropriate size acted significantly in well-controlled crystal growth and the enlargement of surface area via the pore-forming function. The Pt cocatalyst was loaded by the photochemical deposition method to investigate its photocatalytic activity for H2H2 evolution from an aqueous ethanol solution. The Pt/PEG-modified TiO2TiO2 photocatalyst showed higher photocatalytic activity than Pt/unmodified TiO2TiO2 and Pt/Degussa P25-TiO2TiO2, among which Pt/PEG6000-TiO2TiO2 demonstrated the highest activity with an average H2H2 evolution rate of 1615μmolh-1. Therefore, the utilization of PEG to modify the microstructure of TiO2TiO2 was proved to be an efficient way to acquire improved photocatalytic performance. The extended studies of the reaction at different temperatures and from a series of hydrocarbon sacrificial reagents were also performed over Pt/PEG6000-TiO2TiO2. The results were helpful to obtain further understanding of the photocatalytic reaction.

Composites consisting of silver and lanthanum stabilized bismuth oxide (La0.15Bi0.85O1.5) were investigated as cathodes for intermediate-temperature solid oxide fuel cells with doped ceria as electrolyte. No stable phases were formed via reaction between La0.15Bi0.85O1.5 and Ag. The microstructure of the interfaces between composite cathodes and Ce0.8Sm0.2O1.5 electrolytes was studied by scanning electron microscopy after sintering at various temperatures. Impedance spectroscopy measurements revealed that the performance of cathode fired at 700 °C was the best. When the optimum fraction of Ag was 50 vol.%, polarization resistance values for the LSB-Ag50 cathode were as low as 0.14 Ω cm2 at 700 °C and 0.18 Ω cm2 at 650 °C. The steady-state polarization investigations on LSB and LSB-Ag50 cathodes were performed using typical three-electrode test cells in air. The results showed that the LSB-Ag50 composite cathode exhibited a lower overpotential and higher exchange current density than LSB, which indicated the electrochemical performance of LSB-Ag50 for the oxygen reduction reaction was superior to the LSB.

BaTi4O9 powders with improved crystal perfection and relatively large surface area were synthesized by the polymerized complex (PC) method calcined at reduced temperatures (700–1,000 °C) relative to the solid-state reaction (SSR) method. BaTi4O9 with a unique pentagonal-prism tunnel structure, combined with different cocatalysts (Pt, Ru, Ni, Cu, Co) as promoters, was investigated towards photocatalytic reactions for H2 evolution from pure water and aqueous ethanol solution. Pt/BaTi4O9 achieved the highest activity from ethanol solution, and subsequently it was focused to study the effect of calcination temperature on photocatalytic activities. The maximum quantum yield for H2 evolution from pure water and ethanol solution was obtained at 700 and 800 °C separately, with the value of 0.9% and 11.7% over Pt/BaTi4O9 photocatalysts.

We report here the performance of a metal-based integrated composite membrane electrode assembly (IC-MEA) in direct methanol fuel cell (DMFC). The IC-MEA integrates the multi-functions of a conventional MEA, gas diffusion layer (GDL) and current collector. It was fabricated by impregnating Nafion electrolyte into a sandwiched structure containing expanding-Polytetrafluoroethylene (e-PTFE) and porous titanium sheets and subsequently coating with catalyst layer and microporous layer (MPL). While operating with air and 2 M methanol under ambient pressure, the IC-MEA in DMFC can yield a maximum power density of 19 mW cm−2 at 26 °C, higher than a in-house made Nafion 115 MEA under the same working conditions. The IC-MEAs has been successfully applied to planar multi-cell stacks.

A bifunctional RuO2–IrO2/Pt electrocatalyst for the unitized regenerative fuel cell (URFC) was synthesized by colloid deposition and characterized by analytical methods like TEM, XRD, etc. The result reveals that RuO2–IrO2 was well dispersed and deposited on the surface of Pt black. With deposited RuO2–IrO2/Pt as the catalyst of oxygen electrode, the performance of fuel cell/water electrolysis of unitized regenerative fuel cell (URFC) was studied in detail. URFC with deposited RuO2–IrO2/Pt shows better performance than that of URFC with mixed RuO2–IrO2/Pt catalyst. Cyclic performance of URFC with deposited RuO2–IrO2/Pt is very stable during 10 cyclic tests.

The solid solution of CaTi1−xZrxO3 (x = 0–0.15) was successfully synthesized by the polymerized complex (PC) method. This study has exhibited the advantage of the PC method to prepare a highly active CaTiO3 compared with the conventional solid-state reaction (SSR) method. More importantly, further improvement in phase purity and large surface area was achieved by the doping of Zr4+, leading to remarkable enhancement of photocatalytic activities compared to pure CaTiO3. The quantum yield for H2 evolution over the most active photocatalyst, Pt (1.0 wt%)/CaTi0.93Zr0.07O3, was 1.91% and 13.3% in photoreactions from pure water and aqueous ethanol solution, respectively for 0.1 g photocatalyst, which was about 3.3 and 2.5 times compared to that of PC-derived CaTiO3.

Dense BaCe0.8Sm0.2O2.90 (BCSO) thin films were successfully fabricated on porous NiO–BCSO substrates by dry pressing process. As characterized by scanning electron microscope, the BCSO films were about 50 μm. With Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) as cathodes, single cells were tested at 600 and 700 °C with humidified (3% HB2O) hydrogen as fuel and oxygen as oxidant. The open circuit voltage of 1.049 V at 600 °C and 1.032 V at 700 °C were achieved, indicating negligible gas permeation through the BCSO thin films. Maximum power densities of 132 and 340 mW/cm2 were obtained at 600 and 700 °C, respectively. The impedance measurements at open circuit conditions showed that there were two rate-limiting processes for the electrode reactions and that the cell performances were essentially determined by the electrode polarization resistances at temperature below 650 °C, which implied that it was essential to reduce the electrode polarization by developing novel electrode materials to improve the performance of ITSOFC based on BCSO electrolyte. Conductivities of BCSO under the cell operating circumstances were obtained as 0.00416, 0.00662 and 0.00938 Scm− 1 at 500, 600 and 700 °C, respectively. The activation energy of BCSO conductivity was calculated as 29.5 and 43.8 kJ/mol for the temperature range of 550–700 °C and of 400–550 °C, respectively. Endurance test was firstly carried out with 75 μm BCSO electrolyte at 650 °C at the operating voltage of 0.7 V and current density about 0.12 A/cm2. Both voltage and current density remained stable for 1000 min.

The He-reference method and modified tangent-mass method are introduced to measure and calculate the hydrogen storage capacity of carbon nanotubes by using high-pressure microbalance. These two methods can correctly calibrate the effect of buoyancy and determine the adsorption isotherm. Well-aligned carbon nanotubes were measured by two methods to provide reference data for future studies.

We studied the electrochemical hydrogen storage properties of activated carbon (AC) material mixed with copper. The discharge capacity of AC–Cu electrode which reached 510 mAh/g after 384 cycles, is much higher than that of the CNT–Cu electrodes. The plateau of discharge potential for AC–Cu electrode was very long and flat and reached −0.88 V vs. Hg/HgO, which was far from the potential of copper oxidation. The discharge plateau gradually appeared and continually lengthened with the increase of cycle number. Cyclic voltammetric experiments showed that the adsorption and desorption of hydrogen occurred on the surface of activated carbon and the active site increased with the increase of cycle number. The mechanism for electrochemical storage of hydrogen in AC–Cu electrode may be mainly physisorption.