Facile Approach for Improving the Interfacial Adhesion of Nanofiber Air Electrodes of Reversible Solid Oxide Cells.

Nanofibers have great promise as a highly active air electrode for reversible solid oxide cells (ReSOCs); however, one thorny issue is how to adhesively stick nanofibers to electrolyte with no damage to the original morphology. Herein, PrBa0.8Ca0.2Co2O5+δ (PBCC) nanofibers are applied as an air electrode by a facile direct assembly approach that leads to the retention of most of the unique microstructure of nanofibers, and firm adhesion of the nanofiber electrode onto the electrolyte is achieved by applying electrochemical polarization. A single cell with the PBCC nanofiber air electrode exhibits excellent maximum power density (1.97 W cm-2), electrolysis performance (1.3 A cm-2 at 1.3 V), and operating stability at 750 °C for 200 h. These findings provide a facile means for the utilization of nanofiber electrodes for high-performance and durable ReSOCs.

Ultrafine, Dual-Phase, Cation-Deficient PrBa0.8Ca0.2Co2O5+δ Air Electrode for Efficient Solid Oxide Cells.

Nanostructured air electrodes play a crucial role in improving the electrocatalytic activity of oxygen reduction and evolution reactions in solid oxide cells (SOCs). Herein, we report the fabrication of a nanostructured BaCoO3-decorated cation-deficient PrBa0.8Ca0.2Co2O5+δ (PBCC) air electrode via a combined modification and direct assembly approach. The modification approach endows the dual-phase air electrode with a large surface area and abundant oxygen vacancies. An intimate air electrode-electrolyte interface is in situ constructed with the formation of a catalytically active Co3O4 bridging layer via electrochemical polarization. The corresponding single cell exhibits a peak power density of 2.08 W cm-2, an electrolysis current density of 1.36 A cm-2 at 1.3 V, and a good operating stability at 750 °C for 100 h. This study provides insights into the rational design and facile utilization of an active and stable nanostructured air electrode of SOCs.

Alloy Metal Nanocluster: A Robust and Stable Photosensitizer for Steering Solar Water Oxidation.

Metal nanoclusters (NCs) have been unleashed as an emerging category of metal materials by virtue of integrated merits including the unusual atom-stacking mode, quantum confinement effect, and fruitful catalytically active sites. Nonetheless, development of metal NCs as photosensitizers is blocked by light-induced instability and ultrashort carrier lifespan, which remarkably retards the design of metal NC-involved photosystems, hence resulting in the decreased photoactivities. To solve these obstacles, herein, we conceptually probed the charge transfer characteristics of the BiVO4 photoanode photosensitized by atomically precise alloy metal NCs, wherein tailor-made l-glutathione-capped gold-silver bimetallic (AuAg) NCs were controllably self-assembled on the BiVO4 substrate. It was uncovered that alien Ag atom doping is able to effectively stabilize the alloy AuAg NCs and simultaneously photosensitize the BiVO4 photoanode, significantly boosting the photoelectrochemical (PEC) water oxidation performances. The reasons for the robust and stable PEC water oxidation activities of the AuAg NCs/BiVO4 composite photoanode were unambiguously unleashed. We ascertain that Ag atom doping in the staple motif of Aux NCs efficaciously protects the NCs from rapid oxidation, enhancing the photostability, boosting the photosensitization efficiency, and thus leading to the considerably improved PEC water splitting activities compared with the homometallic counterpart. This work could afford a new strategy to judiciously tackle the inherent detrimental instability of metal NCs for solar energy conversion.

Study on the enhanced electron-hole separation capability of IrxZn1-xO/Ti electrodes with high photoelectrocatalysis efficiency.

Making full use of low-energy photons and reducing photogenerated carriers' recombination rate have been considered important ways to raise photoelectrocatalysis (PEC) efficiency. In this study, Ir-doped ZnO PEC electrodes were prepared by thermal decomposition method, first principles calculations were used to study the effects of Ir content on the electronic structure and optical properties of IrxZn1-xO coatings, the PEC degradation mechanism of the IrxZn1-xO/Ti electrodes was also tentatively presented. The results indicated that with numbers of Zn atoms replaced by Ir atoms, impurity energy level appeared in ZnO band gap, which reduced the electron transition barriers and increased the number of photogenerated carriers. Besides, IrO2 nanoparticles covered on ZnO nanorods surface, acting as highly efficient electron transfer channels and electrocatalytic active sites, could separate photogenerated electron-hole pairs and enhance PEC performance effectively. PEC performance of IrxZn1-xO/Ti electrodes with different Ir contents under UV irradiation was evaluated by rhodamine B (RhB) removal rate. Compared with pure ZnO electrodes, IrxZn1-xO/Ti ones exhibited much stronger degradation capacity. Specifically, Ir0.09375Zn0.90625O/Ti electrodes showed the highest degradation rate of 99.4 %, and a relatively high rate of 95.2 % after working 100 h continuously, indicating its excellent long-term stability.

Influence of the electronic structures on the heterogeneous photoelectrocatalytic performance of Ti/RuxSn1-xO2 electrodes.

DSA-type Ti/RuxSn1-xO2 electrodes were prepared by thermal decomposition method as photoelectrocatalysts (PECs) and extensively characterized by various sophisticated techniques. First-principles calculations was employed to study the effects of Ru content on the electronic structures of the RuxSn1-xO2 coatings. The photoelectric-synergistic catalytic activity of the Ti/RuxSn1-xO2 electrodes was evaluated for the degradation of methyl orange (MO) in aqueous solution. The results show that the RuO2-SnO2 solid solution could be formed. The band gaps of the RuxSn1-xO2 coatings gradually decreased and eventually turned into metallic conductivity with the increase of ruthenium content. As a PEC electrode, reducing band gap is helpful to improve electronic conductivity and the electrocatalytic activity, but not always advantageous to increase the photocatalytic activity. Because too narrow band gap will sacrifice the photogenerated charge carriers and thus reduce photocatalytic activity of the electrode. In our experiments, the rate constant of Ti/Ru0.05Sn0.95O2 electrode increased with increasing Ru content and exhibited the maximum rate for 5% Ru loading. The stability test showed the photoelectrocatalytic activity of the Ti/Ru0.05Sn0.95O2 electrode almost had no attenuation after 100h photoelectrolysis, revealing that this electrode has good long-term stability.

Stability and spinodal decomposition of the solid-solution phase in the ruthenium-cerium-oxide electro-catalyst.

The phase diagram of Ru-Ce-O was calculated by a combination of ab initio density functional theory and thermodynamic calculations. The phase diagram indicates that the solubility between ruthenium oxide and cerium oxide is very low at temperatures below 1100 K. Solid solution phases, if existing under normal experimental conditions, are metastable and subject to a quasi-spinodal decomposition to form a mixture of a Ru-rich rutile oxide phase and a Ce-rich fluorite oxide phase. To study the spinodal decomposition of Ru-Ce-O, Ru0.6Ce0.4O2 samples were prepared at 280 °C and 450 °C. XRD and in situ TEM characterization provide proof of the quasi-spinodal decomposition of Ru0.6Ce0.4O2. The present study provides a fundamental reference for the phase design of the Ru-Ce-O electro-catalyst.