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In this work, we prepared a novel material of cobalt nanorods@ cobalt-platinum nanoparticles using a facile, green method. We used a hydrothermal method to first synthesize a cobalt nanorod, which was used as a substrate material on which a ZIF-67 MOF structure was controllably loaded, and then, platinum was loaded into the MOF using a redox substitution reaction, resulting in the formation of a new type of nanocomposites, cobalt nanorods@ cobalt-platinum nanoparticles. The composites were successfully doped with a small amount of precious metal platinum into cobalt nanorods @ cobalt MOF by replacement method, which combines the unique structure of cobalt nanorods, cobalt MOF and high electrocatalytic performance of platinum, realizes the organic combination of precious metal-transition metal and effectively improves the electrocatalytic performance of the composites. The novel composites Co NRs@Co 10 –Pt 1 NPs exhibit high catalytic activity and stability for the hydrogen and oxygen evolution reactions, Tafel slopes is 25 mV dec−1 in HER and 56 mV dec−1 in OER. This work provides a new idea for the preparation step of novel transition metal-precious metal composites and contributes to the effective improvement of the material's performance in electrocatalytic water decomposition reaction. • Cobalt-platinum nanoparticles coated on cobalt nanorods. • Trace noble metal doping greatly improves electrocatalytic performance. • Nanorod structures and small-sized nanoparticles provide more active sites. • High electrocatalytic performance for oxygen and hydrogen evolution reactions. [ABSTRACT FROM AUTHOR]

In this paper, a reflux solar methanol steam reforming reactor (SMSRR) system is proposed for efficient solar thermal hydrogen produced. A two-dimensional (2D) axisymmetric model is used to compare the comprehensive performance of three different SMSRRs: no reflux tube (SMSRR0), flow from the inside of the reflux tube to the outside (SMSRR1) and flow from the outside of the reflux tube to the inside (SMSRR2). The results showed that the reflux SMSRR uses the heat of the fluid at the outlet to further provide the reaction heat, which greatly reduces the outlet temperature, thereby improving the overall performance of the SMORE. By optimizing the diameter of the reflux tube and the operating conditions, the energy conversion rate can be increased by 19.5%, and the temperature distribution coefficients can be increased by 1.89% while the methanol conversion is increased by 6.43%, and the hydrogen yield is increased by 5.96%. • A new solar receiver-reactor of reflux structure is proposed. • A three-dimensional comprehensive model was established for solar receiver-reactors with secondary reflection.. • The optimized reflux reactor greatly reduces ΔT io , thereby improving the energy conversion efficiency. • The reflux structure in the optimized systems enables the reactor to obtain better uniformity of the temperature field. [ABSTRACT FROM AUTHOR]

Micro Fuel cells or microfluidic fuel cells (μMFCs) are one of the most promising power supplies for portable electronics. However, the necessary electrode spacing is required to prevent fuel-crossover and maintain the stable operation, introducing the unavoidable ohmic resistance and retarding the miniaturization. Herein, we propose a novel μMFC device combining the cellulose paper as separator, with selective catalysts at the cathode side to eliminate the unwanted side reactions and increase the system compactness. One single reactant solution containing fuel and electrolyte is applied to keep the device stable operation. The power-generation properties are evaluated in typical alkaline conditions. A great construction simplification makes the device a substantial high-power density of 2.14 W cm−3 and maximum current density of 15.82 A cm−3. The μMFC stacks are arranged in series and parallel manners, which delivers a maximum power output of 23.6 mW and current of 194.6 mA. It is expected that innovative and customizable performance from commercial paper and low-cost carbonaceous catalysts can provide a forum for future advancement in chip-based electrochemical energy generation and storage devices. • Filter paper served as a membrane for μMFC is proposed. • The electrode-pair distance is greatly minimized (∼140 μm). • The optimized μMFC delivers an ultrahigh power density of 2.14 W cm−3. • The μMFC stacks power output of 23.6 mW and current output of 194.6 mA are achievable. [ABSTRACT FROM AUTHOR]

Abstract Precise control of hydrogen pressure is crucial for the performance and durability of fuel cell systems. With the widely used common-rail injection system, traditional PID controller still dominates. For a long time, the hydrogen pressure fluctuates acutely when hydrogen purge valve switches or load sharply changes with using PID controller. In recent studies, several new control strategies are presented. However, mostly of them are theoretical and experimental. In this study, an improved common-rail injection system, hydrogen injector/ejector assembly is introduced. Based on a real fuel cell system, a Mamdani fuzzy controller is designed to regulate the hydrogen pressure. The algorithm of fuzzy controller is explained in detail. A comparative study is carried out between fuzzy controller and PID controller. According to the results, the stability of hydrogen pressure with using fuzzy controller is better than using PID controller. This research could be useful for the control of fuel cell system. Highlights • The characters of hydrogen pressure's fluctuation was studied. • A Mamdani-type fuzzy control system was designed to controller the hydrogen pressure in fuel cell system. • The algorithm of the fuzzy controller was introduced in detail. • The controller was proved to be valid and effective for real fuel cell systems. • A comparative study is carried out between fuzzy controller and PID controller. [ABSTRACT FROM AUTHOR]

Rapid cold start of proton exchange membrane fuel cell (PEMFC) stack is imperative for the widespread of fuel cell vehicles. In the present work, a two-dimensional transient model of PEMFC stack with coolant recirculation is developed to investigate the cold start characteristics with different strategies. Six different current loading modes are evaluated under −20 °C including constant current loading modes and constant slope ramp current loading modes with various current increase rates and different initial water content. The temperature distribution, ice volume fraction distribution in in-plane and through-plane directions, as well as the output voltage, voltage loss, voltage consistency and coolant temperature are monitored and comprehensively analyzed. The results show that a constant slope ramp current loading mode with relatively large initial current density and appropriate initial water content is beneficial to rapid start-up due to the gradual hydration of the membrane and the increase of temperature. [Display omitted] • A 2D transient cold start model with coolant recirculation is developed. • The influence of current loading modes on cold start process is discussed. • Relationship between voltage consistency and ice distribution is analyzed. • A constant slope ramp current loading strategy is proposed for rapid cold start. [ABSTRACT FROM AUTHOR]

One of the bottleneck problems in the application of hydrolysis hydrogen production technology is the stability and continuity of activity of electrode at large current density. Herein, an ingenious hierarchical self-supporting wood-based carbon electrocatalyst are developed to improve the efficiency and stability of hydrogen evolution at large current density. The wood-carbon framework with open microchannels achieves efficient mass transfer and overall stability of the electrode under long-term high current density. Significantly, metal-organic framework derived cobalt–nickel Metal bridges (Co, Ni–N–C) facilitate the tight interfacial bonding of wood and nickel–cobalt binary alloy nanoparticles, and achieves the coordination of conductivity, stability and porosity in the wood framework and the migration of the d-band center, thereby enhancing the hydrogen evolution reaction (HER) performance and superior durability. This work provides an efficient method for industrial scale application of wood based self-supported hydrogen evolution electrocatalyst electrode. [Display omitted] • Biological porous structural characteristics of wood were retained. • MOF-derived N@CoNi layer in carbonization wood was constructed. • M(CoNi)–N–C bonding realized CoNi layer firmly coated on carbonization wood. • CoNi alloy achieves negative shift of d-band center. • CoNiNP–N@CoNi/CW has excellent HER performance at large current. [ABSTRACT FROM AUTHOR]

Abstract: A mixed phototrophic sludge was enriched from the sediment of a local river for continuous hydrogen production from acetate and butyrate in a complete-mix reactor. At pH 7.0–7.5 and , the optimal hydrogen production rate at 48 h of hydraulic retention time (HRT) for 150 days of steady-state operation averaged with of biomass. The sludge yield averaged -VSS/g-COD. Results of batch experiments showed an optimal pH of 8.5 and an optimal concentration of 2mM for hydrogen production. At 10mM, severely inhibited the hydrogen production. Three of the five OTUs classified from 26 clones developed from the seed sludge were phototrophs, based on phylogenetic analysis. Among them, OTU LA15, which is closely related to Rhodobacter sp., was most likely responsible to the hydrogen production. [Copyright &y& Elsevier]

The development of efficient and low-cost alternatives to precious metals as electrocatalysts for electrochemical oxygen evolution (OER), hydrogen evolution (HER) and oxygen reduction (ORR) reactions is an urgent task to solve the current resource shortage problem. Here, we designed a novel enoki shaped catalyst in which FeNi alloy was grown and P was doped on the top of carbon nanotubes (EM-FeNiP@HCNT). The positive repulsion effect between PDDA and Fe2+Ni2+ made FeNi alloy oriented to grow on the top of the carbon nanotubes. C 18 -L-Glu and pyrrole were used as template and carbon source, respectively. After high temperature calcination, C 18 -L-Glu surfactant template was removed, the hollow nanotube structure was formed, the N element was doped and the FeNi ion was reduced to FeNi alloy by one step. EM-FeNiP@HCNT provides superior HER/OER/ORR performance owing to its specific morphology, porous structure, doped P and the synergistic effect between FeNi alloy and P. The prepared EM-FeNiP@HCNT is capable of driving 10 mA cm−2 at 294 (OER) and −224 mV (HER), respectively. The initial and half-wave potential in the ORR reaction require only 0.90 V and 0.78 V. Moreover, the number of transferred electrons of EM-FeNiP@HCNT in the ORR reaction reaches 3.89. The synergistic effect between FeNi and P atom doped carbon substrates provides high electrocatalytic activity and high stability for HER, OER and ORR, which is comparable to or better than that of commercial RuO 2 or Pt/C catalysts. Meanwhile, density functional theory (DFT) calculation shows the composite has low adsorption energy (0.80 V, HER; −2.21 eV, OER/ORR). Therefore, the prepared EM-FeNiP@HCNT shows great application potential as a three-function electrocatalyst. A three-function P-doped catalyst with FeNi alloy directionally grown on the top of carbon nanotubes was prepared; it showed high activity for OER, HER and ORR catalysis. [Display omitted] • Novel catalyst with flammulina mushroom-like structure. • FeNi alloy grows directionally on the top of carbon nanotubes. • Synergistic effect between FeNi alloy and P enhances the catalytic activity. • Catalyst has high specific surface area, large pore structure and high catalytic activity. • High catalytic performance for HER, OER and ORR. [ABSTRACT FROM AUTHOR]

The geometry configuration of proton exchange membrane fuel cell (PEMFC) which is considered as a promising energy conversion device has great influence on PEMFC performance. In this paper, effect of channel-to-rib width ratio and relative humidity of reactant gas on the performance are compared based on two single PEMFCs. The EIS testing results below 50 A are given and analyzed. The results obtained from polarization curves, power density curves and EIS fitting results prove that: 1. Compared with cell 3:4, the anode high humidification has a greater addition to the performance of cell 1:1; 2. PEMFCs with different geometry configurations of flow field have their own suitable working condition ranges; 3. The charge transfer resistance is the dominating factor when current loading is below 2.0 A cm−2. • The performance of two single PEMFCs was evaluated and compared. • EIS fitting results are analyzed with equivalent circuit. • Geometric configuration plays different role under different loading amplitudes. • Charge transfer resistance dominates performance when loading is under 2 A cm−2. [ABSTRACT FROM AUTHOR]

The oxygen starvation in fuel cells is an important reason for the deterioration of durability. The segmented fuel cell is a method to study the gas distribution inside the fuel cell. In order to study the influence of the grooving method on segmented fuel cell and its application in oxygen starvation diagnosis, a five-serpentine-channel three-dimensional two-phase simulation model is established by FLUENT. Through steady-state simulation, the effect of grooving method on fuel cell performance is studied. The overall performance (polarization curve) of the fuel cell drops slightly, but the current density distribution on the anode graphite plate changes greatly due to the grooves. The "current concentration" phenomenon is proposed based on the current density distribution. Through dynamic simulation, the oxygen starvation under current load mode and voltage load mode is simulated, and the "starvation coefficient" is defined as an oxygen starvation diagnostic index. In the current load mode, the "starvation coefficient" never exceed 15%, because when the oxygen starvation is severe, the simulation cannot converge or even cannot maintain, which corresponds to the voltage reversal in reality. However, in the voltage load mode, the "starvation coefficient" can reach up to 100%. The conclusions have important guiding significance for the judgment of the internal reaction uniformity of the segmented fuel cell by grooving method and provide a theoretical basis for judging whether a fuel cell is out of oxygen by segmented fuel cell. • A two-phase CFD simulation model of segmented fuel cell is established. • "Current concentration" phenomenon is proposed based on the current distribution. • "Starvation coefficient" is defined as an oxygen starvation diagnostic index. • Oxygen starvation under current load mode and voltage load mode is compared. [ABSTRACT FROM AUTHOR]

The number of hydrogen refuelling stations worldwide has increased to over 700 due to the rapid development of green hydrogen energy. The risk assessment of hydrogen refuelling stations is indispensable to prevent accidents, and its foundation is accident scenarios screening. Although the integrated energy supply station containing fuels such as hydrogen, compressed natural gas (CNG), methanol eliminates the need for building hydrogen refuelling stations separately, the risk assessment for these complex systems has not been comprehensively studied. This paper proposes a scenario screening approach for identifying potential hazards in multi-fuel integrated energy supply stations. The risk of the processing unit was evaluated, and the leakage scenarios were pre-screened to identify credible leakage scenarios that adhere to the principle of maximum credibility by considering the frequency of occurrence and severity of consequences in two parts. Based upon acquired credible leakage scenarios, secondary screening of possible accident consequences was conducted by calculating the value of the credible factor to obtain the final maximum credible accident scenarios (MAS). Credible factors are derived from the accident probability, consequence severity, population density and asset density. By comparing the values of the credible factors, the accident scenarios with a low probability or low severity were eliminated, and the accident scenarios with the highest credible factors of each unit were retained as the MAS that require further consequence simulation analysis. The results offer a crucial foundation for the consequences and risk assessment of integrated energy supply stations. • Potential consequences of accidents caused by hydrogen and other fuel leaks. • Credible scenarios for fuel leaks are identified. • Maximum credible accident scenarios are determined. • Hydrogen compressor and associated piping are most susceptible to jet fires and explosions. [ABSTRACT FROM AUTHOR]

In this work, a new type of Fe 3 O 4 nanoparticles encapsulated in and loaded on hollow carbon nanotubes (HCNTs) wrapped dendritic carbon layers (DCL) architecture were synthesized successfully by a simple method. In the preparation process, hollow polypyrrole (PPy) tubes were used as the base material, iron phthalocyanine (FePc) was applied as iron and carbon source, and the iron in FePc was successfully reduced to Fe 3 O 4 by the reducibility of hydrogen peroxide which were successfully embedded in the hollow PPy tubes and loaded on the outer wall of the PPy tubes. Meanwhile, phthalocyanine, as a carbon source, was wrapped in the outer layer of hollow PPy. After calcination, a carbon layer coated with Fe 3 O 4 nanoparticles was formed. Moreover, iron as a precursor catalyzed to take shape dendritic carbon layers structure during high temperature calcination. Ultimately, the novel Fe 3 O 4 nanoparticles coated in HCNTs and encapsulated in dendritic carbon layers have been successfully prepared which have a relatively unique morphology and structure by an innovative, green and simple preparation method. Fe 3 O 4 nanoparticles are not only embedded in the interior of HCNTs, but also loaded on the outer wall of HCNTs. Greater specific surface area and better electrocatalytic performance are displayed in acquired 2Fe 3 O 4 @N-HCNT@2Fe 3 O 4 @DCL in oxygen evolution reactions (OER) and hydrogen evolution reactions (HER). In this work, a novel method of metal oxide embedding into void internal structure is developed, and a relatively new morphology is obtained, which provides a new train of thought for the progress of material preparation. [Display omitted] • Fe 3 O 4 nanoparticles embedded into and loaded on HCNT with dendritic carbon layer. • A novel structure formed between organic specie and inorganic iron precursor. • Gradient structure formed by competitive cross-linking and polymerization reaction. • 2Fe 3 O 4 @N-HCNT@2Fe 3 O 4 shows high electrocatalytic performance for OER and HER. [ABSTRACT FROM AUTHOR]

Due to the large difference in atomic size between Zr and Nb, TiVNbZr high entropy alloy possesses greater lattice distortion. The change of Zr content can affect the stability of hydrides, which can have an important impact on the hydrogen storage performance. In order to explore the effect of Zr/Nb on hydrogen storage properties, Ti 32.5 V 27.5 Nb 40- x Zr x (x = 7.5, 10, 12.5, 15) high entropy alloys composed of BCC phase are designed. It is found that with the increase of Zr/Nb, the dendritic microstructures first disappear and then gradually become coarse. The Zr-rich BCC phase and the Nb-rich BCC phase appear in the interdendritic and dendritic regions, respectively. Ti 32.5 V 27.5 Nb 25 Zr 15 shows excellent activation performance, which is related to the Zr-rich BCC phase with the most catalytic phase on the surface. The hydrogen storage performance of low Zr/Nb composition is better at low temperature, and that of high Zr/Nb composition becomes better after rising to high temperature. This is because with the change of Zr/Nb, low temperature can promote the hydrogen absorption reaction and high temperature can increase the diffusion rate of hydrogen atoms in the interstitial positions of the alloy. Ti 32.5 V 27.5 Nb 32.5 Zr 7.5 achieves the best hydrogen absorption capacity of 1.71 wt % at 150 °C. All components undergo a transition from the BCC phase to the FCC phase during the hydrogen absorption process, and then change to a single-phase BCC structure after dehydrogenation. With the increase of Zr content, the first step desorption temperature raises in turn, owing to the stronger thermal stability of hydride. • The formation of Zr-rich BCC phase is beneficial to the improvement of hydrogen storage performance. • With the increase of Zr/Nb ratio, TiVNbZr high-entropy alloy can obtain greater lattice distortion. • The Zr-rich BCC phase has better sensitivity at high temperatures, but it is less sensitive to low temperatures. [ABSTRACT FROM AUTHOR]

In this work, we prepared a nitrogen-doped right-chiral carbon nanotubes @ porous Ni–Fe alloy nanoparticles (N-D-HCNT@pNi-Fe NPs). In the preparation process, a chiral amino acid chain (C 18 -D-Glu) was used as the template, in which pyrrole was polymerized as carbon and nitrogen source. According to the connection between pyrrole and transition metal ions, the transition metal ions were loaded onto C 18 -D-Glu. After one step of high temperature calcination process, nitrogen doping, removal of pore-forming agent, reduction of transition metal nanoparticles and synthesis of chiral carbon nanotubes were completed in one step. Combined with the chiral structure of chiral carbon nanotubes, the high electrocatalytic performance of metal alloy nanoparticles and the high specific surface area formed by the porous structure, the composite obtained high electrocatalytic performance in oxygen evolution (OER) and hydrogen evolution reactions (HER). This study provides a new idea for the application of chiral carbon nanotubes in the field of electrocatalytic energy and a new method for the preparation of composite materials based on chiral carbon nanotubes. • Prepared N-doped right-chiral carbon nanotubes @ porous Ni–Fe alloy nanoparticles. • Pyrrole as C, N sources, P123 as pore-forming agents and metal ions as precursors. • N doping, pore-forming agent removal, metal ions reduction by one-step calcination. • High specific surface area of chiral CNTs and porous structure of Ni–Fe alloys. • High electrocatalytic performance for oxygen and hydrogen evolution reactions. [ABSTRACT FROM AUTHOR]

Reactant starvation is unfavorable to the durability and life extension of PEMFC engines. In this paper, a 25 cm2 segmented PEMFC is assembled to investigate starvation phenomenon, and the contour maps of current distribution are given to analyze the reactant starvation mechanism. The experimental results prove the high-quality homogeneity of current with triple-serpentine configuration even under starvation conditions. The air starvation experiments suggest the migration of lowest current region and the variation trend of standard deviation with the increasing of stoichiometry. The survival time increases with the anode stoichiometry, and the current density of anode downstream constantly increases with the reversal of cell, reflecting severe hydrogen starvation in these local areas. It is concluded ORR dominates the specific current distribution rather than any other electrochemical reactions. This study sheds the light of improving the lifespan and potential large-scale commercialization realization of PEMFC engines. [Display omitted] • Systematical analysis on reactant starvation of PEMFC was performed. • Triple-serpentine flow field exhibits excellent homogeneity of current density. • The lowest current area moves downstream with the increment of air supply. • Behavior of current density near the outlet closely relates to hydrogen supply. • Complexity of involved reactions affects the uniformity of current distribution. [ABSTRACT FROM AUTHOR]

The contact pressure distribution plays a key role to the proton exchange membrane (PEM) fuel cell performance. The purpose of this study is to propose an equivalent stiffness model combined with an equivalent beam model to predict the contact pressure distribution for a large fuel cell stack. With the established equivalent stiffness model, the equivalent values of contact pressure is revealed. Moreover, these equivalent values are extended by an iterative calculation for contact pressure distribution with an established equivalent beam model. Finally, the presented model is compared to a three-dimensional FEA model. This equivalent stiffness model has high accuracy only with a 4.1% tolerance and the correlation coefficient of FEA and equivalent beam model for the contact pressure distribution at transverse and longitudinal direction is 0.976 and 0.998. This presented equivalent model is effective and can provide a direction for future work on high-performance fuel cell stack design and optimization. • Contact pressure distribution is important to the PEM fuel cell performance. • Equivalent stiffness model can obtain the contact pressure value. • Equivalent beam model can predict the contact pressure distribution. • The effectiveness of the presented model is validated with a FEA model. [ABSTRACT FROM AUTHOR]

Gd 5 Mg 95-x Ni x (x = 5,10,15) alloys were melted in a vacuum induction furnace, and the phase composition, microstructure and storage properties of gaseous hydrogen were investigated using scanning electron microscopy (SEM) and X-ray diffractometry (XRD). Hydrogen storage performance includes hydrogen absorption/desorption capacity, particle powder and platform pressure. The activation energy, entropy and enthalpy of the dehydrogenation reaction were calculated. The results show that GdMg 5 , Mg 2 Ni are the main phase and the secondary phase of the alloys respectively. After hydrogen absorption, the main phase transformation is MgH 2 , and the secondary phases are Mg 2 NiH 4 and GdH 3. After dehydrogenation, the main phase transformation is Mg, and the secondary phases are Mg 2 Ni and GdH 2. GdH 3 has poor thermal stability and can be easily decomposed into GdH 2. Hydrogen storage capacity gradually decreases as the nickel content increases, but the kinetic performance is significantly improved. The change in nickel content has no significant effect on the thermodynamic. • Gd 5 Mg 95-x Ni x (x = 5,10,15) alloys were prepared by vacuum induction melting. • The alloys have excellent hydrogen storage properties after only one activation. • Gd 5 Mg 85 Ni 10 alloy has a reversible hydrogen storage capacity of up to 5.84 wt% at 360 °C. • Gd 5 Mg 85 Ni 10 alloy has good kinetic and thermodynamic properties. [ABSTRACT FROM AUTHOR]

Carbon-assisted water electrolysis uses carbon oxidation reaction replacing oxygen evolution reaction to decrease the anode potential and the energy consumption for water electrolysis hydrogen production. However, the mass transfer between carbon particle-electrolyte-anode limits its energy saving effect. Based on the principle of self-corrosion/oxidation of carbon-based electrode materials, the biochar sacrificial anode was proposed and investigated to solve the mass transfer issue in carbon slurry assisted water electrolysis for hydrogen production. Results showed that the activity and stability of sacrificial anode could be improved simultaneously in high concentration alkaline electrolyte using pinewood char as active substance, graphite as conductive agent and coal liquefying residue as binder. The biochar anode produced less oxygen than Pt anode, and the anode potential of biochar was 60–76% of that Pt anode. The application of biochar as sacrificial anode offers an industrial clean, scalable and sustainable idea to obtain green hydrogen. • The substitution of OER was achieved by biochar sacrificial anode. • The sacrificial anode avoids mass transfer of carbon assisted water electrolysis. • The optimal ratio of biochar/graphite/binder is 1:1:1. • Cell voltage of water electrolysis reduced about 20%. • Larger size anode could extend service life biochar sacrificial anode. [ABSTRACT FROM AUTHOR]

Abstract: This paper proposes a hierarchical model for automotive fuel cell system evaluation, comparison and applicability assessment through Analytic Hierarchy Process. A dual-layer criterion based hierarchical model is proposed, which features 9 sub-performances and 18 indices. Criterion weights and scoring function are both established. Experimental application is carried out to illustrate the evaluation process and how the proposed model operates. Results show that the sub-performance derived from automotive powertrain requirements represented the overall characteristics of the PEMFCs. The selected 18 most significant indices also made each sub-performance quantitatively assessable. [Copyright &y& Elsevier]

Abstract: Batch tests were conducted to investigate the effect of co-substrates, including glucose, xylose and starch, on thermophilic anaerobic conversion of microcrystalline cellulose using mixed culture enriched from anaerobic digestion sludge (ADS). Up to 30.9% of cellulose was utilized with xylose as co-substrate. When using glucose as co-substrate, cellulose conversion rate reached the maximum of 0.048 g/l/h at cellulose loading of 5.0 g/l. Illumina high-throughput sequencing of the 16S rRNA gene revealed that the thermophilic consortium exclusively consisted of Clostridium (more than 70% of all sequences). Growth of Thermoanaerobacterium over Clostridium would inhibit cellulose conversion capacity of the consortium. But the growth of Thermoanaerobacterium could be repressed by pH higher than pH 6.0. Co-substrates caused noticeable variation of bacterial community structure. Predominance of Thermoanaerobacterium over Clostridium was observed when monosugars (glucose and xylose) were used as co-substrate without pH control. Starch was ineffective as co-substrate because it competed with cellulose for Clostridium. [Copyright &y& Elsevier]

Abstract: The effect of ferrous ion (0–3.2mg/l) on photo heterotrophic hydrogen production was studied in batch culture using sodium lactate as substrate. The results showed that hydrogen production by Rhodobacter sphaeroides was significantly suppressed when was limited. Hydrogen production increased linearly with an increase in concentration in the range of 0–1.6mg/l; reaching a maximum at 2.4mg/l. When hydrogen production was suppressed in the above medium, a pH increase to 8.9 was observed, and the ratio of lactate utilized to total organic carbon removal was found to be increased, indicating that more soluble organic products were produced. Under the limited conditions, ferrous iron was shown to have a greater effect on hydrogen production by Rb. sphaeroides than that by the anaerobic heterotrophic bacterium Clostridium butyricum. [Copyright &y& Elsevier]

Abstract: Phototrophic hydrogen production from glucose by pure and co-cultures of Clostridium butyricum and Rhodobacter sphaeroides was studied in batch experiments. Results showed that in all batches hydrogen was produced after a lag phase of about 10h; pure culture of R. sphaeroides produced hydrogen at rates substantially lower than C. butyricum. In co-culture systems, R. sphaeroides even with cell populations 5.9 times higher still could not compete with C. butyricum for glucose. In co-culture systems, R. sphaeroides syntrophically interacted with C. butyricum, using the acetate and butyrate produced by the latter as substrate for hydrogen production. Hydrogen production was ceased in all batches when the pH was lowered to the level of pH 6.5, resulting from the accumulation of fatty acids. It was also demonstrated in this study that fluorescence in situ hybridization (FISH) was an effective means for the quantification of the relative abundance of individual bacteria in a co-culture system. [Copyright &y& Elsevier]

Abstract: Batch experiment results showed that hydrogen production from rice slurry was found most effective at pH 4.5, 37°C treating a slurry containing 5.5g-carbohydrate/L. An anaerobic digester sludge was used as seed after a 100°C heat treatment for 30min. After a 36h acclimation period, the sludge had a maximum specific hydrogen production rate of 2.1L/(g-VSSd) and a hydrogen yield of 346mL/g-carbohydrate, corresponding to 62.6% of stoichiometric yield. The effluent was composed mostly of acetate (28.3–43.0%) and butyrate (51.4–70.9%). Based on the 16S rDNA analysis, the 28 clones developed from this acidophilic hydrogen-producing sludge may be classified into nine OTUs, all of which are affiliated with the genus Clostridium. Phylogenetic analysis shows that eight OTUs (96.4% of population) form a distinct group with Clostridium sp. 44a-T5zd. Results indicate the acidophilic hydrogen-producing bacteria found in this study are unknown, and warrant further studies. [Copyright &y& Elsevier]

Abstract: Phototrophic hydrogen production was conducted using individual substrates, acetate and butyrate, which are the main products of dark fermentation. Effects of initial pH (ranging 5.0–10.0) and individual substrate concentrations (acetate ranging from 800 to 4100mg/l, and butyrate ranging from 1000 to 5100mg/l) on phototrophic hydrogen production were evaluated. The maximum hydrogen yields were 2.5mol-H2/mol-acetate at an initial pH of 8.0 treating 800mg/l of acetate, 3.7mol-H2/mol-butyrate at an initial pH of 9.0 treating 1000mg/l of butyrate. Analyses of DGGE (denaturing gradient gel electrophoresis) profiles of 16S rDNA fragments and FISH (fluorescent in situ hybridization) images show that both phototrophic hydrogen-producing sludges comprised only one predominant species resembling Rhodobacter capsulatus with over 80% relative abundance. [Copyright &y& Elsevier]

Widely acknowledged by experts, the inconsistency between the cells of the proton exchange membrane fuel cell stack during operation is an important cause of the fuel cell life decay. Existing studies mainly focus on qualitative analysis of the effects of operating parameters on fuel cell stack consistency. However, there is currently almost no quantitative research on predicting the voltage consistency through operating parameters with machine learning methods. To solve this problem, a three-dimensional model of proton exchange membrane fuel cell stack with five single cells is established in this paper. The Computational Fluid Dynamic (CFD) method is used to provide the source data for prediction model. After predicting the voltage consistency with several machine learning methods and comparing the accuracy through simulation data, the integrated regression method based on Gradient Boosting Decision Tree (GBDT) gets the highest score (0.896) and is proposed for quickly predicting the consistency of cell voltage through operating parameters. After verifying the GBDT method with the experimental data from the fuel cell stack of SUNRISE POWER, in which the accuracy score is 0.910, the universality and accuracy of the method is confirmed. The influencing sensitivity of each operating parameter is evaluated and the current density has the greatest influence on the predicted value, which accounts for 0.40. The prediction of voltage consistency under different combination of operating parameters can guide the optimization of structural parameters in the process of the fuel cell design and operating parameters in the process of fuel cell control. • Predict voltage consistency through operating parameters with machine learning. • Gradient Boosting Decision Tree (GBDT) method gets the highest score. • The universality and accuracy of GBDT method are verified by experiments. • The influencing sensitivity of each parameter is evaluated. [ABSTRACT FROM AUTHOR]

Abstract As an energy conversion device that converts hydrogen energy into electrical energy, the fuel cell is one of the most promising. Starvation is the main reasons that shortens the lifetime of Proton Exchange Membrane Fuel Cell (PEMFC) for vehicle usage. Therefore, combining the experimental and simulation results, as well as previous studies, based on the external characteristics of PEMFCs, the mechanism of judging the starvation in PEMFCs is explored. It provides a theoretical basis for judging the starvation using external characteristics. In addition, the starvation index is proposed to solve the problem that the starvation in the process of fuel cell loading, which could not be evaluated in the past. This factor can provide guidance for matching and controlling the fuel cell supply system, as well as optimizing the internal structural parameters of the fuel cell. [ABSTRACT FROM AUTHOR]

This paper presents the design and simulation validation of two energy management strategies for dual-stack fuel cell electric vehicles. With growing concerns about environmental issues and the fossil energy crisis, finding alternative methods for vehicle propulsion is necessary. Proton exchange membrane (PEM) fuel cell systems are now considered to be one of the most promising alternative energy sources. In this work, the challenge of further improving the fuel economy and extending the driving range of a fuel cell vehicle is addressed by a dual-stack fuel cell system with specific energy management strategies. An efficiency optimization strategy and an instantaneous optimization strategy are proposed. Simulation validation for each strategy is conducted based on a dual-stack fuel cell electric vehicle model which follows the new European driving cycle (NEDC). Simulation results show that a dual-stack fuel cell system with proposed energy management strategies can significantly improve the fuel economy of a fuel cell vehicle and thus lengthen the driving range while being able to keep the start-stop frequency of the fuel cell stack within a reasonable range. [ABSTRACT FROM AUTHOR]