Zheng Liu,Su Zhang,Zhipeng Qiu,Chao Huangfu,Lin Wang,Tong Wei,Zhuangjun Fan
Tin (Sn) is considered to be an ideal candidate for the anode of sodium ion batteries. However, the design of Sn-based electrodes with maintained long-term stability still remains challenging due to their huge volume expansion (≈420%) and easy pulverization during cycling. Herein, a facile and versatile strategy for the synthesis of nitrogen-doped graphene quantum dot (GQD) edge-anchored Sn nanodots as the pillars into reduced graphene oxide blocks (NGQD/Sn-NG) for ultrafast and ultrastable sodium-ion storage is reported. Sn nanodots (2–5 nm) anchored at the edges of “octopus-like” GQDs via covalent Sn O C/Sn N C bonds function as the pillars that ensure fast Na-ion/electron transport across the graphene blocks. Moreover, the chemical and spatial (layered structure) confinements not only suppress Sn aggregation, but also function as physical barriers for buffering volume change upon sodiation/desodiation. Consequently, the NGQD/Sn-NG with high structural stability exhibits excellent rate performance (555 mAh g −1 at 0.1 A g −1 and 198 mAh g −1 at 10 A g −1 ) and ultra-long cycling stability (184 mAh g −1 remaining even after 2000 cycles at 5 A g −1 ). The confinement-induced synthesis together with remarkable electrochemical performances should shed light on the practical application of highly attractive tin-based anodes for next generation rechargeable sodium batteries.
Developing smart luminescent materials with desirable and tunable characteristics has always been an overriding priority of fluorescence technology. However, huge challenges encompass the single functionality of the luminescent materials and the traditional chemical synthetic techniques with rigorously controlling over the miscellaneous experimental conditions and variables. Herein, the lanthanide-doped bismuth-layered ferroelectric (Na 0.5 Bi 0.5 ) 0.96 Er 0.04 Bi 2 Nb 2 O 9.02 has been prepared to be utilized as a platform that not only serves the in-situ and reversible tailoring of the upconverted emission via physical methods, but also enable the versatile functionalities such as photomemory and multi-modal temperature sensing. High luminescent contrast that can reach up to 83.7 % before and after the 405 nm irradiation has been realized on the basis of the photochromic phenomenon of the as-prepared (Na 0.5 Bi 0.5 ) 0.96 Er 0.04 Bi 2 Nb 2 O 9.02 sample, and the fundamental application in the photomemory has been exhibited. Moreover, the performances of triple-mode thermometry built on the fluorescent intensity ratio techniques ( 2 H 11/2 / 4 S 3/2 and 4 S 3/2 / 4 F 9/2 ) as well as the lifetime of the 4 S 3/2 excited state of the Er 3+ ion have been investigated in carefulness, with the maximal relative sensitivities of 1.22 % K −1 at 300 K, 0.92 % K −1 at 510 K, and 0.18 % K −1 at 450 K, respectively. Our results provide significant insights into the methodology of physically modulating the upconversion luminescence, and offer a glamorous pathway for multifunctional high-end applications.
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