Scientists HAN Keli et al. from Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS), synthesized a new lead-free Cs3Bi2Br9 nanocrystal (NC) and revealed the photophysical mechanism of it. The results were published in Angew. Chem. Int. Ed. (DOI: 10.1002/anie.201704739)
　　PLQE can be increased from 0.2% to 4.5% when oleic acid is added during the synthesis processes 
　　Lead-based perovskite NCs with formula APbX3 (A: Cs, CH3NH3 (MA), X=Cl, Br, I) have received broad attentions for their excellent optical and electronic properties.
　　The perovskite nanostructures have high PL quantum efficiency (PLQE), large absorption cross-section, low-threshold for lasing, and tunable PL emission in the whole UV-Vis range due to the quantum confinement. However, the toxic of lead-based materials pose a threat to the environment and humankind.
　　Furthermore, the application of perovskite NCs is still limited by their instability in air. Thus, searching for low toxic and highly stable perovskite NCs is on the cutting-edge of the research.
　　Scientists found that the PLQE can be increased from 0.2% to 4.5 % when oleic acid is added during the synthesis processes. They have determined that this improvement stems from the passivation of fast trapping process which is 2~20 ps.
　　Notably, the trap-states could also be passivated in humid condition and the NCs exhibited high stability towards air exposure exceeding 30 days. (Text and Image by YANG Bin)

　　Scientists HAN Keli et al. from Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS), synthesized a new lead-free Cs3Bi2Br9 nanocrystal (NC) and revealed the photophysical mechanism of it. The results were published in Angew. Chem. Int. Ed. (DOI: 10.1002/anie.201704739)
　　PLQE can be increased from 0.2% to 4.5% when oleic acid is added during the synthesis processes 
　　Lead-based perovskite NCs with formula APbX3 (A: Cs, CH3NH3 (MA), X=Cl, Br, I) have received broad attentions for their excellent optical and electronic properties.
　　The perovskite nanostructures have high PL quantum efficiency (PLQE), large absorption cross-section, low-threshold for lasing, and tunable PL emission in the whole UV-Vis range due to the quantum confinement. However, the toxic of lead-based materials pose a threat to the environment and humankind.
　　Furthermore, the application of perovskite NCs is still limited by their instability in air. Thus, searching for low toxic and highly stable perovskite NCs is on the cutting-edge of the research.
　　Scientists found that the PLQE can be increased from 0.2% to 4.5 % when oleic acid is added during the synthesis processes. They have determined that this improvement stems from the passivation of fast trapping process which is 2~20 ps.
　　Notably, the trap-states could also be passivated in humid condition and the NCs exhibited high stability towards air exposure exceeding 30 days. (Text and Image by YANG Bin)

　　As post-lithium ion batteries, both sodium ion batteries (SIBs) and potassium ion batteries (PIBs) possess great potential for large scale energy storage. However, the improvements of both SIBs and PIBs for practical applications are facing great challenges in the development of high-performance electrode materials.
　　MXenes, a large family of 2D transition metal carbides and carbonitrides have gained widespread interest as emerging potential host materials for metal (Li, Na, K, Mg) ion batteries. It's due to their unique morphology, high theoretical capacity which are 447.8, 351.8, 191.8 mAh/g for Li, Na, K on Ti3C2, respectively, and flexible interlayer space capable of handling high rate capability.
　　However, multilayer MXene nanosheets with small interlayer space for large ionic radius of Na+ and K+, usually show limited reversible capacities as well as poor cyclic stability. Therefore, rationally designing novel MXene based nanostructures with suitable interlayer spacing and stable structure, using innovative synthesis strategies, is of great significance for improving sodium and potassium storage kinetics of SIBs and PIBs.
　　Alkalized Ti3C2 (a-Ti3C2) MXene nanoribbons synthesized by continuous shaking treatment of pristine Ti3C2 MXene in aqueous KOH solution.
　　Scientists WU Zhongshuai and BAO Xinhe et al. at Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) collaborated with WANG Xiaohui from Institute of Metal Research of CAS, developed alkalized Ti3C2 (a-Ti3C2) MXene nanoribbons with expanded interlayer spacing for high-capacity SIBs and PIBs. This work has been published online in Nano Energy (DOI: 10.1016/j.nanoen.2017.08.002).
　　a-Ti3C2 nanoribbons were successfully synthesized by continuous shaking treatment of pristine Ti3C2 MXene in aqueous KOH solution. Due to the expanded interlayer spacing of a-Ti3C2, the narrow widths of nanoribbons as well as three-dimensional interconnected porous frameworks enhanced the ion reaction kinetics and improved the structure stability. The resulting a-Ti3C2 anodes showed excellent sodium/potassium storage performance. For example, high reversible capacities of 168 and 136 mAh/g at 20 mAh/g，and 84 and 78 mAh/g at 200 mAh/g were obtained for SIBs and PIBs, respectively.
　　Notably, a-Ti3C2 possessed outstanding long-term cyclability at high current density of 200 mAh/g, delivering a capacity of ~ 50 mAh/g for SIBs and ~42 mAh/g for PIBs after 500 cycles. It outperformed the reported MXene based anodes for SIBs and PIBs.
　　Moreover, this alkalization strategy could be extended as a universal approach for fabricating various alkalized MXene-based frameworks derived from a large family of MAX phases for numerous applications, such as catalysis, energy storage and conversion.
　　This work was supported by National Key R&D Program of China, National Natural Science Foundation of China, Natural Science Foundation of Liaoning Province, and DICP and China Postdoctoral Science Foundation. (Text and Image by DONG Yanfeng and ZHAO Xuejun)

　　As post-lithium ion batteries, both sodium ion batteries (SIBs) and potassium ion batteries (PIBs) possess great potential for large scale energy storage. However, the improvements of both SIBs and PIBs for practical applications are facing great challenges in the development of high-performance electrode materials.
　　MXenes, a large family of 2D transition metal carbides and carbonitrides have gained widespread interest as emerging potential host materials for metal (Li, Na, K, Mg) ion batteries. It's due to their unique morphology, high theoretical capacity which are 447.8, 351.8, 191.8 mAh/g for Li, Na, K on Ti3C2, respectively, and flexible interlayer space capable of handling high rate capability.
　　However, multilayer MXene nanosheets with small interlayer space for large ionic radius of Na+ and K+, usually show limited reversible capacities as well as poor cyclic stability. Therefore, rationally designing novel MXene based nanostructures with suitable interlayer spacing and stable structure, using innovative synthesis strategies, is of great significance for improving sodium and potassium storage kinetics of SIBs and PIBs.
　　Alkalized Ti3C2 (a-Ti3C2) MXene nanoribbons synthesized by continuous shaking treatment of pristine Ti3C2 MXene in aqueous KOH solution.
　　Scientists WU Zhongshuai and BAO Xinhe et al. at Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) collaborated with WANG Xiaohui from Institute of Metal Research of CAS, developed alkalized Ti3C2 (a-Ti3C2) MXene nanoribbons with expanded interlayer spacing for high-capacity SIBs and PIBs. This work has been published online in Nano Energy (DOI: 10.1016/j.nanoen.2017.08.002).
　　a-Ti3C2 nanoribbons were successfully synthesized by continuous shaking treatment of pristine Ti3C2 MXene in aqueous KOH solution. Due to the expanded interlayer spacing of a-Ti3C2, the narrow widths of nanoribbons as well as three-dimensional interconnected porous frameworks enhanced the ion reaction kinetics and improved the structure stability. The resulting a-Ti3C2 anodes showed excellent sodium/potassium storage performance. For example, high reversible capacities of 168 and 136 mAh/g at 20 mAh/g，and 84 and 78 mAh/g at 200 mAh/g were obtained for SIBs and PIBs, respectively.
　　Notably, a-Ti3C2 possessed outstanding long-term cyclability at high current density of 200 mAh/g, delivering a capacity of ~ 50 mAh/g for SIBs and ~42 mAh/g for PIBs after 500 cycles. It outperformed the reported MXene based anodes for SIBs and PIBs.
　　Moreover, this alkalization strategy could be extended as a universal approach for fabricating various alkalized MXene-based frameworks derived from a large family of MAX phases for numerous applications, such as catalysis, energy storage and conversion.
　　This work was supported by National Key R&D Program of China, National Natural Science Foundation of China, Natural Science Foundation of Liaoning Province, and DICP and China Postdoctoral Science Foundation. (Text and Image by DONG Yanfeng and ZHAO Xuejun)

　　Prof. ZHANG Tao and Prof. WANG Aiqin’s group in Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) reported new Single-Atom Catalysts (SAC).
　　Single-atom dispersed Fe-N-C catalyst with different active sites for C-H bond selective oxidation（Image by LIU Wengang and ZHANG Leilei）
　　They fabricated a kind of Fe-N-C SAC, which showed excellent catalytic activity and selectivity for C-H oxidation at room temperature. This work has been published in J. Am. Chem. Soc. (DOI: 10.1021/jacs.7b05130).
　　M-N-C materials are considered as the promising substitute of noble metal catalysts (e.g., Pt/C) in electrocatalysis and fine chemical synthesis. However, a great discrepancy exists on the nature of the active sites since the catalysts are heterogeneous in both composition and particle size.
　　In 2016, this group successfully prepared a Co-N-C SAC, which exhibited high activity and selectivity in the hydrogenative coupling of nitroarenes. And they also identified the structure of the active site was CoN4C8-1-2O2 unambiguously (Chem. Sci., 2016, 7, 5758–5764).
　　Based on previous work, this group recently not only fabricated a highly active Fe-N-C SAC, but also demonstrated the heterogeneity of Fe-N-C SAC although all the iron species were atomically dispersed.
　　More importantly, it is found that the under-coordinated Fe-N5, which was only accounted for 18% of all Fe-Nx (x = 4-6) species, stood out to give the best catalytic performance by combining various characterizations and poisoning experiments. This provided a guide to develop more efficient Fe-N-C SAC with more coordination unsaturated Fe-N5.
　　This work was supported by the National Natural Science Foundation of China, the Strategic Priority Research Program of the Chinese Academy of Sciences, and the National Key Projects for Fundamental Research and Development of China. (Text by LIU Wengang and ZHANG Leilei)
　　Dr. WANG Yongjin
　　Dalian Institute of Chemical Physics, Chinese Academy of Sciences,
　　457 Zhongshan Road, Dalian, 116023, China,
　　Tel: 86-411-84374221
　　E-mail: wangyj@dicp.ac.cn 

　　Prof. ZHANG Tao and Prof. WANG Aiqin’s group in Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) reported new Single-Atom Catalysts (SAC).
　　Single-atom dispersed Fe-N-C catalyst with different active sites for C-H bond selective oxidation（Image by LIU Wengang and ZHANG Leilei）
　　They fabricated a kind of Fe-N-C SAC, which showed excellent catalytic activity and selectivity for C-H oxidation at room temperature. This work has been published in J. Am. Chem. Soc. (DOI: 10.1021/jacs.7b05130).
　　M-N-C materials are considered as the promising substitute of noble metal catalysts (e.g., Pt/C) in electrocatalysis and fine chemical synthesis. However, a great discrepancy exists on the nature of the active sites since the catalysts are heterogeneous in both composition and particle size.
　　In 2016, this group successfully prepared a Co-N-C SAC, which exhibited high activity and selectivity in the hydrogenative coupling of nitroarenes. And they also identified the structure of the active site was CoN4C8-1-2O2 unambiguously (Chem. Sci., 2016, 7, 5758–5764).
　　Based on previous work, this group recently not only fabricated a highly active Fe-N-C SAC, but also demonstrated the heterogeneity of Fe-N-C SAC although all the iron species were atomically dispersed.
　　More importantly, it is found that the under-coordinated Fe-N5, which was only accounted for 18% of all Fe-Nx (x = 4-6) species, stood out to give the best catalytic performance by combining various characterizations and poisoning experiments. This provided a guide to develop more efficient Fe-N-C SAC with more coordination unsaturated Fe-N5.
　　This work was supported by the National Natural Science Foundation of China, the Strategic Priority Research Program of the Chinese Academy of Sciences, and the National Key Projects for Fundamental Research and Development of China. (Text by LIU Wengang and ZHANG Leilei)
　　Dr. WANG Yongjin
　　Dalian Institute of Chemical Physics, Chinese Academy of Sciences,
　　457 Zhongshan Road, Dalian, 116023, China,
　　Tel: 86-411-84374221
　　E-mail: wangyj@dicp.ac.cn