Yttrium doped Barium cerate and Zirconate heterostructures: deposition and electrochemical characterization

Epitaxial heterostructures consisting of an yttrium doped barium cerate (BCY) layer sandwiched between two yttrium doped barium zirconate (BZY) thin layers have been deposited on insulating (001) MgO substrates by pulsed laser deposition. The first BZY layer was aimed at improving the lattice match with the MgO substrate, the second at protecting the BCY layer. Ionic conductivity has been studied in the 300 – 600°C temperature range as a function of the BCY thickness. Due to the absence of blocking grain boundaries, heterostructures showed a conductivity larger than that of BCY pellets sintered under optimized conditions

La0.8Sr0.2Ga0.8Mg0.2O3-δ thin films for IT-SOFCs: Microstructure and transport properties correlation.

Highly textured La0.8Sr0.2Ga0.8Mg0.2O3 (LSGM) films with columnar structure were grown by pulsed laser deposition on (001) NdGaO3 and SrTiO3 buffered (001) MgO substrates. Combined analysis of the films structure and morphology and EIS measurements showed that the transport properties are mainly limited by perpendicular grain boundaries effects. Increasing the film thickness, columnar nanosized grains tend to coalesce leading to a decrease of grain boundary concentration, hence to enhanced conductivity

Spin-coated La0.8Sr0.2Ga0.8Mg0.2O3-δ Electrolyte on Infiltrated Anodes for Direct Methane Fuel Cells

Dense micrometric La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM) films were deposited by spin-coating on porous LSGM scaffolds characterized by homogeneous pore structure. Porous anodes were infiltrated with aqueous nickel and nickel/copper nitrate solutions, dried and fired at 700°C. Homogeneous metal coating with proper interconnection was observed by SEM, chemical stability was confirmed by XRD, and electrical characterization of anodic substrates was performed. Catalytic activity of different anodes was evaluated ex-situ in a quartz micro-reactor fed with CH4:CO2 mixtureat range 650 and 700°C. To investigate the redox properties of the metallic phases, the anodic substrates were subjected to redox ageing cycles and characterized by H2-TPR

Using olive mill wastewate to improve performance in producing electricity from domestic wastewater by using single-chamber microbial fuel cell

Improving electricity generation from wastewater (DW) by using olive mill wastewater (OMW) was evaluated using single-chamber microbial fuel cells (MFC). Doing so single-chambers air cathode MFCs with platinum anode were fed with domestic wastewater (DW) alone and mixed with OMW at the ratio of 14:1 (w/w). MFCs fed with DW + OMW gave 0.38 V at 1 kO, while power density from polarization curve was of 124.6mW m 2. The process allowed a total reduction of TCOD and BOD5 of 60% and 69%, respectively, recovering the 29% of the coulombic efficiency. The maximum voltage obtained from MFC fed with DW + OMW was 2.9 times higher than that of cell fed with DW. DNA-fingerprinting showed high bacterial diversity for both experiments and the presence on anodes of exoelectrogenic bacteria, such as Geobacter spp. Electrodes selected peculiar consortia and, in particular, anodes of both experiments showed a similar specialization of microbial communities independently by feeding used

CO2/CH4 Reforming High Temperature Proton Conductor(HTPC) Fuel Cells

High temperature proton conductors (HTPCs) based fuel cells directly fed with methane mixtures were investigated. Doped barium zirconate was chosen as electrolyte because of its good chemical stability in CO2 and H2O containing atmosphere. The sintering temperature of doped barium zirconate was decreased down to 1350◦C by doping with 1wt.% ZnO. A co-pressing method was used for fabricating anode supported single cell. Flat and reproducible bottom cell of NiO-BZYZn / BZYZn / Pt were produced. OCV measurements, I-V curves, and impedance spectra were recorded in the 600-750◦C temperature range. The addition of carbon dioxide to methane improved SOFC stability by suppressing coking in Ni anodes

Electrochemical performance of spin coated dense BaZr0.80Y0.16Zn0.04O3-d membranes

The high sintering temperature of Yttrium doped barium zirconate (BZY), the most promising high temperature proton conductor (HTPC) for Intermediate Temperature (400e750 C) Solid Oxide Fuel Cells (IT-SOFCs), has been reduced by using ZnO as a sintering aid. Obtaining a dense electrolyte at a reduced temperature allows conventional fuel cell preparation methods. A reproducible spin coating method to fabricate highly performing anode supported button cells with dense micrometric BZYZn electrolyte layers has been developed. The electrochemical characterization of button cells at 600 C shows promising performance, higher than that of comparable fuel cells from literatur

Organically functionalized titanium oxide/Nafion composite proton exchange membranes for fuel cells applications

An organically-modified ceramic material (TiO2eRSO3H) to be used as filler in Nafion-based composite membranes was synthesized by covalently grafting propylsulfonic acid groups on the surface of TiO2 nanoparticles. Higher ion exchange capacity (IEC) and proton conductivity of the hybrid material (one order of magnitude higher for the functionalized filler) reflected in superior performance of Nafion/TiO2eRSO3H composite membranes compared to Nafion. The highest conductivity value was obtained for the com- posite membrane containing 10 wt. % TiO2eRSO3H (s 1⁄4 0.08 S cm 1 at 140 C). The membranes were tested in a DMFC single cell. The presence of the filler resulted in a general enhancement in the cell response, in terms of both higher power density (PD) delivered and lower methanol crossover with respect to unfilled Nafion membrane. The DMFC containing N_10TiO2eRSO3H membrane showed the best performance at 110 C with a PD of 64 mW cm 2, corresponding to a PD improvement of about 40% with respect to that of Nafion membrane

Development of Nafion/Tin Oxide Composite MEA for DMFC applications

International audienceNafion composite membranes containing either hydrated tin oxide (SnO₂•nH₂O) or sulfated tin oxide (S-SnO₂) at 5 wt.% and 10 wt.% were prepared and characterized. The structural and electrochemical features of the samples were investigated using X-ray diffraction, electrochemical impedance spectroscopy, methanol crossover, and direct methanol fuel cell (DMFC) tests. Highest conductivity values were obtained by using S-SnO₂ as filler (0.094 Scm^-1 at T=110°C and RH=100%). The presence of the inorganic compound resulted in lower methanol crossover and improved DMFC performance with respect to a reference unfilled membrane. To improve the interface of the membrane electrode assembly (MEA), a layer of the composite electrolyte (i.e., the Nafion membrane containing 5 wt% S-SnO₂) was brushed on the electrodes, obtaining a DMFC operating at 110°C with a power density (PD) of 100 mWcm^-2 which corresponds to a PD improvement of 52% with respect to the unfilled Nafion membrane