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Exploring the fine-structure of cesium lead bromide (CsPbBr3) perovskite nanocrystals (NCs) is not only vital to fundamental understanding of recombination mechanism of exciton but also crucial for improving the performance of quantum light emitters and spintronic devices. Herein, utilizing low-temperature magneto-photoluminescence (PL) measurement, we provide the direct PL spectral feature of the dark exciton in CsPbBr3single crystal, and demonstrate that the singlet dark exciton is located ∼20 meV below the triplet bright exciton. Furthermore, no significant polarization effect was measured from magnetic-polarization method, indicating that there is no spin selectivity for dark exciton.

Sr-doped LaMnO3, as one of the most successful cathodes for solid oxide fuel cells (SOFCs), can effectively function at high temperatures. However, its cathode kinetics considerably decreases with decreasing temperature, rendering it unsuitable for SOFCs operating at intermediate temperatures. In this study, La0.5Sr0.5MnO3−δ(LSM) is coated with TiO2to create the LSM + TiO2cathode. TiO2is shown to modify the electronic structure at the LSM/TiO2interface, allowing for charge accumulation for the O atoms at the interface. The activated O atoms enhance the formation of oxygen vacancies, which benefit the oxygen diffusion ability. Using LSM + TiO2as a cathode for proton-conducting SOFCs (H-SOFCs) operating at intermediate temperatures, the corresponding fuel cell demonstrated enhanced cell output performance compared with cells employing solely LSM or TiO2cathodes, exhibiting the synergistic effect of combining LSM and TiO2. Additionally, the LSM + TiO2cells achieved a power output of 1118 mWcm−2at 700°C, the highest yet reported value for H-SOFCs with LSM cathodes. LSM + TiO2was demonstrated to be stable against CO2and steam, allowing for steady functioning of the cell under working conditions, thereby resolving the problem of LSM’s poor performance in H-SOFCs while retaining remarkable stability.

The Ba0.5Sr0.5Co0.8Fe0.2O3−δ(BSCF) + Co3O4composite material is evaluated as a cathode for proton-conducting solid oxide fuel cells (H-SOFCs), which provides a new strategy to solve the thermal mismatch problem between the cathode and electrolyte without impairing the cathode performance. BSCF is a well-known cathode material for intermediate-temperature SOFCs, but its performance for H-SOFCs is unsatisfactory. One reason for the relatively low performance is the poor contact between the BSCF cathode and the electrolyte due to the high thermal expansion of BSCF. The relatively low melting point of Co3O4is taken in this study as an advantage to bond the BSCF cathode to the electrolyte, mitigating the poor contact problem for the BSCF with the electrolyte. Furthermore, the addition of Co3O4promotes the catalytic activity of the BSCF cathode as demonstrated by experimental studies and first-principles calculations, leading to an impressively high performance of BSCF-based cathodes for H-SOFCs.

Sc-doped Sr2Fe1.5Mo0.5O6−δ(SFMSc) was successfully synthesized by partially substituting Mo in Sr2Fe1.5Mo0.5O6−δ* (SFM) with Sc, resulting in a higher proton diffusion rate in the resultant SFMSc sample. Theoretical calculations showed that doping Sc into SFM lowered the oxygen vacancy formation energy, reduced the energy barrier for proton migration in the oxide, and increased the catalytic activity for oxygen reduction reaction. Next, a proton-conducting solid oxide fuel cell (H-SOFC) with a single-phase SFMSc cathode demonstrated significantly higher cell performance than that of cell based on an Sc-free SFM cathode, achieving 1258 mW cm−2at 700°C. The performance also outperformed that of many other H-SOFCs based on single-phase cobalt-free cathodes. Furthermore, no trade-off between fuel cell performance and material stability was observed. The SFMSc material demonstrated good stability in both the CO2-containing atmosphere and the fuel cell application. The combination of high performance and outstanding stability suggests that SFMSc is an excellent cathode material for H-SOFCs.

Sr-doped LaMnO3(LSM) which is the first-generation cathode for solid oxide fuel cells (SOFCs) has been tailored with Zn ions, aiming to achieve improved protonation ability for proton-conducting SOFCs (H-SOFCs). The new Sr and Zn co-doped LaMnO3(LSMZ) can be successfully synthesized. The first-principle studies indicate that the LSMZ improves the protonation of LSM and decreases the barriers for oxygen vacancy formation, leading to high performance of the LSMZ cathode-based cells. The proposed LSMZ cell shows the highest fuel cell performance among ever reported LSM-based H-SOFCs. In addition, the superior fuel cell performance does not impair its stability. LSMZ is stable against CO2, as demonstrated by both in-situCO2corrosion tests and the first-principles calculations, leading to good long-term stability of the cell. The Zn-doping strategy for the traditional LSM cathode with high performance and good stability brings back the LSM cathode to intermediate temperatures and paves a new way for the research on the LSM-based materials as cathodes for SOFCs.

Proton-conducting oxides offer a promising electrolyte solution for intermediate temperature solid oxide fuel cells (SOFCs) due to their high conductivity and low activation energy. However, the lower operation temperature leads to a reduced cathode activity and thus a poorer fuel cell performance. La0.8Sr0.2MnO3−δ(LSM) is the classical cathode material for high-temperature SOFCs, which lack features as a proper SOFC cathode material at intermediate temperatures. Despite this, we here successfully couple nanostructured LSM cathode with proton-conducting electrolytes to operate below 600°C with desirable SOFC performance. Inkjet printing allows depositing nanostructured particles of LSM on Y-doped BaZrO3(BZY) backbones as cathodes for proton-conducting SOFCs, which provides one of the highest power output for the BZY-based fuel cells below 600°C. This somehow changes the common knowledge that LSM can be applied as a SOFC cathode materials only at high temperatures (above 700°C). 质子导体氧化物因其高导电性和低活化能, 成为一种很有前途的中温固体氧化物燃料电池(SOFCs)电解质材料. 然而, 较低的操作温度会降低阴极活性, 从而降低燃料电池的性能. La0.8Sr0.2MnO3−δ(LSM)是一种经典的高温SOFCs阴极材料, 但其很多特性不符合中温SOFCs阴极材料的要求. 针对这一问题, 我们成功将纳米化的LSM阴极和质子导体电解质结合在一起, 在600°C下运行, 获得了理想的电池性能. 喷墨印刷技术可以将LSM的纳米结构粒子构筑在Y-掺杂的BaZrO3(BZY)骨架上, 从而作为质子导体SOFCs的阴极. 以此为阴极的单电池成为600°C以下的BZY基燃料电池中输出功率最高的之一. 本工作也打破了LSM只能作为高温SOFCs阴极材料(超过700°C)的传统思维局限.