Daan Cui

Enhanced Oxygen Reduction Activity and Solid Oxide Fuel Cell Performance with a Nanoparticles-Loaded Cathode

Reluctant oxygen-reduction-reaction (ORR) activity has been a long-standing challenge limiting cell performance for solid oxide fuel cells (SOFCs) in both centralized and distributed power applications. We report here that this challenge has been tackled with coloading of (La,Sr)MnO3 (LSM) and Y2O3 stabilized zirconia (YSZ) nanoparticles within a porous YSZ framework. This design dramatically improves ORR activity, enhances fuel cell output (200-300% power improvement), and enables superior stability (no observed degradation within 500 h of operation) from 600 to 800 °C. The improved performance is attributed to the intimate contacts between nanoparticulate YSZ and LSM particles in the three-phase boundaries in the cathode.

Gadolinia-doped ceria barrier layer produced by sputtering and annealing for anode-supported solid oxide fuel cells

We prepared gadolinia-doped ceria (GDC) barrier layers by sputtering and annealing at various temperatures. We then investigated the effects of the GDC barrier layers on the performance of anode-supported solid oxide fuel cells. Sputtering at 200 °C readily produced a uniform, thin layer of cubic GDC. Sputtering and annealing at 900–1100 °C formed uniform, thin, dense films, which effectively prevented the reaction between the yttria-stabilized zirconia electrolyte and the Ba0.5Sr0.5Co0.8Fe0.2O3–δ cathode. The single cells assembled with the thin, dense GDC barrier layers sputtered at 200 °C and annealed at 900–1000 °C exhibited excellent electrochemical performance.

Insight into the oxygen reduction reaction on the LSM|GDC interface of solid oxide fuel cells through impedance spectroscopy analysis

Doped ceria is commonly used to promote the performance of solid oxide fuel cells (SOFCs) with a lanthanum strontium manganite (LSM) cathode, but the oxygen reduction reaction (ORR) activity on the interface between LSM and doped ceria is not conclusive due to the complexity of the cathode and problematic analysis of the impedance spectra. Here, to elucidate the role of the LSM|GDC interface in the ORR, we constructed a simple LSM|GDC interface and analyzed the impedance data using a method based on the calculation of the distribution function of relaxation times (DRT). DRT analysis demonstrates that the ORR on the LSM|GDC interface possesses similar activation energies for oxygen dissociation and the subsequent oxygen atom reduction but involves an easier oxygen incorporation process in comparison with the LSM|YSZ interface. Addition of the GDC interlayer causes a decrease in cell performance because poor LSM|GDC interfaces lead to depressed dominant electrode processes of oxygen dissociation and the subsequent oxygen atom reduction. These results provide useful insight into the ORR on the LSM|GDC interface, favoring the design of a high-performance doped ceria-enhanced LSM cathode.

Tuned depositing Ag clusters on ZrO2 nanocrystals from silver mirror reaction of silver–dodecylamine complexes

We for the first time have synthesized Ag/ZrO2 nanocomposites from silver mirror reaction in toluene, which refers to the reduction of silver–dodecylamine complexes by acetaldehyde (CH3CHO) in the presence of ZrO2 nanocrystals. The obtained nanocomposites show excellent catalytic activity in the successive reduction of p-nitrophenol (4-NP) by NaBH4.

TiO2-modified La0.6Sr0.4Co0.2Fe0.8O3-δ cathode for intermediate temperature solid oxide fuel cells

A La0.6Sr0.4Co0.2Fe0.8O3-delta(LSCF) cathode modified using nanosized TiO2 was direct prepared on the yttria stabilized zirconia (YSZ) electrolyte in an intermediate temperature solid oxide fuel cell. TiO2 prevents reaction between LSCF and YSZ, which would have formed a SrZrO3 phase. The cell with a LSCF-0.25 wt% TiO2 cathode exhibited a current density that was 1.6 times larger than that with a pure LSCF cathode at 0.7 V and 600 degrees C. Electrochemical impedance spectra showed the accelerated incorporation of oxygen anions into the YSZ electrolyte with the TiO2-modified LSCF cathode. The improvement was attributed to the suppressed formation of a non-conductive SrZrO3 layer at the cathode/electrolyte interface