Cr doped Ruddlesden-Popper compound Sr 2 TiO 4 has been successfully modified by fluorine to form a new compound Sr 2 Ti 0.95 Cr 0.05 O 3 F 2 . Structure analysis suggests two types of fluorine in the structure of this new compound, i.e. intralayer and interlayer F, which induce strong built-in electric field within this layered compound. The electric field stems from uneven distribution of F atoms on the two sides of perovskite layers therefore leads to charge disproportionation . DFT calculations suggest that this unique structural feature is highly beneficial for charge dissociations as it breaks the coplanar settlement of conduction band minimum and valence band maximum whilst maintains the 2D charge transportation properties. This is clearly demonstrated by the superior photocatalytic activities of Sr 2 Ti 0.95 Cr 0.05 O 3 F 2 for hydrogen production from water. Apparent quantum efficiency (AQE) as high as 1.16% at 420 ± 20 nm has been achieved which stands as the highest AQE reported on Sr 2 TiO 4 to date. Photoelectrochemical (PEC) analysis confirms improved charge separation conditions and prolonged charge lifetime.
Xingxing Li,Yan Zhu,Nan Zhang,Yansheng Gong,Rui Wang,Huanwen Wang,Jun Jin,Ling Zhao,Beibei He
The development of symmetrical solid oxide fuel cells (SSOFCs) faces a significant challenge in designing electrode materials that exhibit both high activity and stability. In this work, a novel layered perovskite oxide symmetric electrode material PrBaFe 1.8 Hf 0.2 O 5+δ (PBFH) for SSOFCs is proposed and synthesized. Doping Hf at the B-site of PrBaFe 2 O 5+δ (PBF) improves the stability in reducing atmosphere and increases the concentration of oxygen vacancies . Furthermore, a small amount of RuO x is deposited by atomic layer deposition (ALD) onto PrBaFe 1.8 Hf 0.2 O 5+δ scaffold as symmetric electrodes. The surface modification of ALD-RuO x significantly boosts the catalytic activity for both fuel oxidation and oxygen reduction, simultaneously. Compared to PBF electrodes, the interfacial polarization resistances of RuO x -PBFH decrease to 0.77 Ω cm 2 under H 2 /Ar and 0.021 Ω cm 2 under air atmosphere at 800 °C, respectively. At 800 °C, SSOFCs equipped with RuO x -PBFH symmetric electrodes exhibit a high peak power density of 0.85 W cm −2 and 0.41 W cm −2 using humidified hydrogen and propane as fuels, respectively. Moreover, the RuO x -PBFH electrode demonstrates long-lasting performance, displaying high resistance against coking. These findings reveal a facile ALD approach for tailoring symmetric perovskite electrodes, offering robust and efficient electrocatalysis with efficient noble metal utilization.
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