Tailoring the electron-blocking layer by addition of YSZ to Ba-containing anode for improvement of ceria-based solid oxide fuel cell

The in-situ fabrication of an electron-blocking layer between the Ba-containing anode and the ceria-based electrolyte is an effective approach in suppressing the internal electronic leakage in ceria-based solid oxide fuel cell (SOFC). To improve the thickness of the electron-blocking layer and to research the effect of the layer thickness on the improvement of SOFC, a Ba-containing compound (0.6NiO-0.4BaZr_0.1Ce_0.7Y_0.2O_3-δ) modified by Y stabilized zirconia (YSZ) was employed as a composite anode in this research. SEM analyses demonstrated that the thickness of the interlayer can be simply controlled by regulating the proportion of YSZ at anode. The in-situ formed interlayer in the cell with the anode modified by 20?mol% YSZ possesses a thickness of 0.9?µm which is more suitable for the cell achieving an enhanced performance.     

An ionic conductor Ce0.8Sm0.2O2−δ (SDC) and semiconductor Sm0.5Sr0.5CoO3 (SSC) composite for high performance electrolyte-free fuel cell

An advanced electrolyte-free fuel cell (EFFC) was developed. In the EFFC, a composite layer made from a mixture of ionic conductor (Ce_0.8Sm_0.2O_2?δ, SDC) and semiconductor (Sm_0.5Sr_0.5CoO₃, SSC) was adopted to replace the electrolyte layer. The crystal structure, morphology and electrical properties of the composite were characterized by X-ray diffraction analysis (XRD), scanning electron microscope (SEM), and electrochemical impedance spectrum (EIS). Various ratios of SDC to SSC in the composite were modulated to achieve balanced ionic and electronic conductivities and good fuel cell performances. Fuel cell with an optimum ratio of 3SDC:2SSC (wt.%) reached the maximum power density of 741 mW cm^?2 at 550 °C. The results have illuminated that the SDC-SCC layer, similar to a conventional cathode, can replace the electrolyte to make the EFFC functions when the ionic and electronic conductivities were balanced.     

Coating layer-free synthesis of sub-4 nm ordered intermetallic L10-PtCo catalyst for the oxygen reduction reaction

The ordered intermetallic PtM alloys with L1₀ structure are considered as the most promising oxygen reduction reaction (ORR) catalysts owing to the strong chemical bond between Pt and M atoms effectively suppresses the leaching of M atoms. However, the preparation of ultrafine L1₀-PtM alloy nanoparticles with high ordering degree is still a challenge because the nanoparticles tend to agglomerate during high-temperature annealing. Herein, we propose a coating layer-free strategy to controllably synthesize sub-4 nm highly ordered intermetallic L1₀-PtCo catalyst. The strong interaction between N-doped carbon (NC) and PtCo(OH)x effectually inhibits the agglomeration of nanoparticles during thermal treatment, while the O vacancies generated by the thermal decomposition of PtCo(OH)x are beneficial to prepare the highly ordered intermetallic L1₀-PtCo alloy. The as-obtained L1₀-PtCo/NC alloy catalyst shows excellent ORR activity in both half-cell and single cell tests, which is much better than that of disordered A1-PtCo/NC and commercial Pt/C catalysts. This work provides a facile and efficient method for fabricating the ordered intermetallic L1₀-PtM alloy catalysts with high ordering degree.     

Industrial grade rare-earth triple-doped ceria applied for advanced low-temperature electrolyte layer-free fuel cells

In this study, the mixed electron-ion conductive nanocomposite of the industrial-grade rare-earth material (La³⁺, Pr³⁺ and Nd³⁺ triple-doped ceria oxide, noted as LCPN) and commercial p-type semiconductor Ni_0.8Co_0.15Al_0.05Li-oxide (hereafter referred to as NCAL) were studied and evaluated as a functional semiconductor-ionic conductor layer for the advanced low temperature solid oxide fuel cells (LT-SOFCs) in an electrolyte layer-free fuel cells (EFFCs) configuration. The enhanced electrochemical performance of the EFFCs were analyzed based on the different semiconductor-ionic compositions with various weight ratios of LCPN and NCAL. The morphology and microstructure of the raw material, as-prepared LCPN as well the commercial NCAL were investigated and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and energy-dispersive X-ray spectrometer (EDS), respectively. The EFFC performances and electrochemical properties using the LCPN-NCAL layer with different weight ratios were systematically investigated. The optimal composition for the EFFC performance with 70 wt% LCPN and 30 wt% NCAL displayed a maximum power density of 1187 mW cm^?2 at 550 °C with an open circuit voltage (OCV) of 1.07 V. It has been found that the well-balanced electron and ion conductive phases contributed to the good fuel cell performances. This work further promotes the development of the industrial-grade rare-earth materials applying for the LT-SOFC technology. It also provides an approach to utilize the natural source into the energy field.     

Efficient electron-blocking layer-free planar heterojunction perovskite solar cells with a high open-circuit voltage

Perovskite solar cells (PSCs) with a simple device structure are particularly attractive due to their low cost and convenient fabrication process. Herein, highly efficient, electron-blocking layer (EBL)-free planar heterojunction (PHJ) PSCs with a structure of ITO/CH₃NH₃PbI₃/PCBM/Al were fabricated via low-temperature, solution-processed method. The power conversion efficiency (PCE) of over 11% was achieved in EBL-free PHJ-PSCs, which is closed to the value of PSC devices with the PEDOT:PSS as the EBL. It is impressed that the open-circuit voltage (V_oc) up to 1.06 V, an average value of 1.0 V for 43 devices, was obtained in EBL-free PHJ-PSCs. The electrochemical impedance spectroscopy (EIS) results suggested that the high PCE and V_oc are attributed to the relatively large recombination resistance and low contact resistance in EBL-free PHJ-PSCs. The solution-processed, EBL-free PHJ structure paves a boulevard for fabricating high-efficiency and low-cost PSCs.     

Flexible,hole transporting layer-free and stable CH3NH3PbI3/PC61BM planar heterojunction perovskite solar cells

Hole transporting layer (HTL)-free CH₃NH₃PbI₃/PC₆₁BM planar heterojunction perovskite solar cells were fabricated with the configuration of ITO/CH₃NH₃PbI₃/PC₆₁BM/Al. The devices present a remarkable power conversion efficiency (PCE) of 11.7% (12.5% best) under AM 1.5G 100 mW cm⁻² illumination. Moreover, the HTL-free perovskite solar cells on flexible PET substrates are first demonstrated, achieving a power conversion efficiency of 9.7%. The element distribution in the HTL-free perovskite solar cell was further investigated. The results indicated that the PbI₂ enriched near the PC₆₁BM side for chlorobenzene treatment via the fast deposition crystallization method. Without using HTL on the ITO, the device is stable with comparison to that with poly(3,4-ethylenedioxylenethiophene): poly(styrene sulfonate) (PEDOT:PSS) as HTL. In addition, the fabricating time of the whole procedure from ITO substrate cleaning to device finishing fabrication only cost about 3 h for our mentioned devices, which is much more rapid than other structure devices containing other transporting layer. The high efficient and stable HTL-free CH₃NH₃PbI₃/PC₆₁BM planar heterojunction perovskite solar cells with the advantage of saving time and cost provide the potential for commercialization printing electronic devices.     

Device characteristics of amorphous indium-gallium-zinc-oxide channel capped with silicon oxide passivation layers

It was investigated how the amorphous indium-gallium-zinc-oxide (a-IGZO) channel of a back-gate of thin film transistor (TFT) is affected by the deposition of silicon oxide layers on their top surfaces by radio frequency magnetron sputtering. Preliminary investigations showed that the deposition of silicon oxide layer caused damages to the surfaces of pristine silicon wafers resulting in substantial roughening. However, bombardments by the energetic particles involved in the sputtering process seem to have played beneficial roles in that the a-IGZO channel TFTs showed improved performances in respect of the carrier density, field effect mobility, and on-off current ratio. Such improvements are attributed to the modification of the a-IGZO channel to decrease the concentration of oxygen vacancy sites and/or to average the oxygen vacancy sites thereby increasing the carrier concentrations and decreasing the density of trap sites, as revealed in the negative shift of the threshold voltage. On the other hand, such channel modification by the passivation process resulted in the slight increase in the subthreshold swing. It is suggested that the a-IGZO channel TFTs can be passivated by simple sputtering process without etch stop layer since the process rather improved the device performances despite some damages to the passivated surfaces.