Rui Guo,Dongdong Li,Rui Guan,Dechen Kong,Zheng Cui,Ziqi Zhou,Tianmin He
BaCeO3-based proton conductors have comparatively high-proton conductivity, but the low chemical stability and high sintering temperature seriously hinder their practical applications in protonic ceramic fuel cells. Herein, we demonstrate that this limitation can be conciliated by using a triple-doping strategy in a BaZr0.1Ce0.7Y0.2O3−δ (BZCY) electrolyte, where the triply doped BaCe0.7Sn0.1Dy0.15Cu0.05O3−δ (BCSDCu) exhibits better chemical stability and conductivity and lower sintering temperature compared with the pristine BZCY. The phase-pure BCSDCu can be obtained at the sintering temperature of 1100 °C prepared by solid-state reaction. The dense BCSDCu (>95%) is achieved at 1350 °C, which is significantly lower than the 1550 °C of BZCY. The BCSDCu presents competitive proton conductivity of 13.6 mS cm–1 under a moist H2 atmosphere at 600 °C. The anode-supported single cell with the BCSDCu (≈40 μm) as the electrolyte reaches the highest power density of 390 mW cm–2 at 600 °C. On the basis of the distribution of relaxation time analysis, we not only distinguish the contribution of grain and grain-boundary conductivities but also identify the rate-determining step of the single-cell performance. The protonic conductivities, mechanical properties, and impurity clean parts induced by grain size effects are discussed for the BCSDCu proton conductor.
Geng Chen,Yahong Jin,Lifang Yuan,Bo Wang,Jiansheng Huo,Hao Suo,Haoyi Wu,Yihua Hu,Feng Wang
Broadband near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) hold promising potential as next-generation compact, portable, and intelligent NIR light sources. Nonetheless, the lack of high-performance broadband NIR phosphors with an emission peak beyond 900 nm has severely hindered the development and widespread application of NIR pc-LEDs. This study presents a strategy for precise control of energy-state coupling in spinel solid solutions composed of MgxZn1–xGa2O4 to tune the NIR emissions of Cr3+ activators. By combining crystal field engineering and heavy doping, the Cr3+–Cr3+ ion pair emission from the 4T2 state is unlocked, giving rise to unusual broadband NIR emission spanning 650 and 1400 nm with an emission maximum of 913 nm and a full width at half-maximum (fwhm) of 213 nm. Under an optimal Mg/Zn ratio of 4:1, the sample achieves record-breaking performance, including high internal and external quantum efficiency (IQE = 83.9% and EQE = 35.7%) and excellent thermal stability (I423 K/I298 K = 75.8%). Encapsulating the as-obtained phosphors into prototype pc-LEDs yields an overwhelming NIR output power of 124.2 mW at a driving current of 840 mA and a photoelectric conversion efficiency (PCE) of 10.5% at 30 mA, rendering high performance in NIR imaging applications.
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