Surface electronic structure of solid materials plays a critical role in heterogeneous catalysis. However,surface chemical composition of the perovskite oxides is usually dominated by segregated A-site cations and the...Surface electronic structure of solid materials plays a critical role in heterogeneous catalysis. However,surface chemical composition of the perovskite oxides is usually dominated by segregated A-site cations and the amount of oxygen vacancies is relatively low, which seriously restricts their catalytic oxidation property. Here, we prepare perovskite La_xSr_(1-x)CoO_(3-δ)(x = 0.3, 0.5, 0.7) with different Sr doping amount and experiment results show that perovskite LSCO with higher content of surface Sr possesses more oxygen vacancies and better catalytic activity. On this basis, we develop a new experimental strategy to create more surface oxygen vacancies to promote their CO catalytic activity. In this method, we use high active hydrogen atoms(BH^(4-)) as reductant to realize surface in-situ chemical composite modification of La_xSr_(1-x)CoO_(3-δ)(x = 0.3, 0.5, 0.7), which causes their surface reconstruction(surface Sr enrichment).The regulation mainly focuses on the atomic layer level without damaging their bulk phase structure.Different from traditional high temperature annealing under reducing atmosphere, this method is high-efficiency, green and controllable. Furthermore, we study the surface reconstruction process and demonstrated that it is atomic layer engineering on the surface of La_xSr_(1-x)CoO_(3-δ)(x = 0.3, 0.5, 0.7) by X-ray photoelectron spectroscopy(XPS) and X-ray absorption fine structure(XAFS). Our experiment results also show that these samples treated by this method exhibit superior activity for CO oxidation compared with original samples.展开更多
A terpyridine-substituted cyanostilbene derivative(Z)-2-(4′-([2,2′:6′,2″-terpyridin]-4′-yl)-[1,1′-biphenyl]-4-yl)-3-phenylacrylonitrile(CNSTPy) was synthesized and characterized. The compound exhibits remarkable...A terpyridine-substituted cyanostilbene derivative(Z)-2-(4′-([2,2′:6′,2″-terpyridin]-4′-yl)-[1,1′-biphenyl]-4-yl)-3-phenylacrylonitrile(CNSTPy) was synthesized and characterized. The compound exhibits remarkable aggregation-induced emission phenomenon and its single crystal shows a blue emission with fluorescent efficiency as high as 45%. Based on its aggregation state behavior, multiple applications towards exploring its lasing, fluorescence switching and electroluminescence properties were realized. Amplified spontaneous emission(ASE) was observed from the crystal and verified by the variable pump strip method, with a threshold value of ～1.5 m J cm^(-2). The protonation/deprotonation processes accompanied by the formation of different molecular aggregation structure result in the distinct blue and yellow emissions. Additionally, the molecule also shows a moderate electroluminescence performance.展开更多
基金supported by the National Natural Science Foundation of China (21671076,21427802 and 21131002)
文摘Surface electronic structure of solid materials plays a critical role in heterogeneous catalysis. However,surface chemical composition of the perovskite oxides is usually dominated by segregated A-site cations and the amount of oxygen vacancies is relatively low, which seriously restricts their catalytic oxidation property. Here, we prepare perovskite La_xSr_(1-x)CoO_(3-δ)(x = 0.3, 0.5, 0.7) with different Sr doping amount and experiment results show that perovskite LSCO with higher content of surface Sr possesses more oxygen vacancies and better catalytic activity. On this basis, we develop a new experimental strategy to create more surface oxygen vacancies to promote their CO catalytic activity. In this method, we use high active hydrogen atoms(BH^(4-)) as reductant to realize surface in-situ chemical composite modification of La_xSr_(1-x)CoO_(3-δ)(x = 0.3, 0.5, 0.7), which causes their surface reconstruction(surface Sr enrichment).The regulation mainly focuses on the atomic layer level without damaging their bulk phase structure.Different from traditional high temperature annealing under reducing atmosphere, this method is high-efficiency, green and controllable. Furthermore, we study the surface reconstruction process and demonstrated that it is atomic layer engineering on the surface of La_xSr_(1-x)CoO_(3-δ)(x = 0.3, 0.5, 0.7) by X-ray photoelectron spectroscopy(XPS) and X-ray absorption fine structure(XAFS). Our experiment results also show that these samples treated by this method exhibit superior activity for CO oxidation compared with original samples.
基金financially supported by the National Natural Science Foundation of China (21835001, 51773080, 21674041, 51573068, 21221063, and 81870117)the Program for Changbaishan Scholars of Jilin Province, Jilin Province project (20160101305JC)+1 种基金Jilin Province Science and Technology Development Plan (20190201252JC)“Talents Cultivation Program” of Jilin University
基金supported by the Hong Kong Research Grants Council (C6009-17G)the Areas of Excellence Scheme of HKSAR (Ao E/P-03/08)+2 种基金the Clarea Au Endowed Professorship in Energy (847S)the Hong Kong Polytechnic University (1-ZE1C)the Hong Kong Research Grants Council for the financial support
文摘A terpyridine-substituted cyanostilbene derivative(Z)-2-(4′-([2,2′:6′,2″-terpyridin]-4′-yl)-[1,1′-biphenyl]-4-yl)-3-phenylacrylonitrile(CNSTPy) was synthesized and characterized. The compound exhibits remarkable aggregation-induced emission phenomenon and its single crystal shows a blue emission with fluorescent efficiency as high as 45%. Based on its aggregation state behavior, multiple applications towards exploring its lasing, fluorescence switching and electroluminescence properties were realized. Amplified spontaneous emission(ASE) was observed from the crystal and verified by the variable pump strip method, with a threshold value of ～1.5 m J cm^(-2). The protonation/deprotonation processes accompanied by the formation of different molecular aggregation structure result in the distinct blue and yellow emissions. Additionally, the molecule also shows a moderate electroluminescence performance.
