Elevated ground-level ozone (O 3 ), reflecting atmospheric oxidative capacity, are of increasing concern. High levels of total oxidants (O x = O 3 + NO 2 ) have been persistently observed as a feature of Beijing's air pollution. Beijing is a well-known megacity requiring the enforcement of stringent air quality controls as rapid economic growth continues. To evaluate the effect of air quality controls in recent years, ground-based on-line measurements at an urban site were conducted in summer and the variations in O 3 with simultaneous changes in NO x and volatile organic compounds (VOCs) between 2005 and 2011 were analyzed. Both NO x and total VOCs in Beijing decreased over the study period, 1.4 ppbv yr −1 and 1.6 ppbv yr −1 , respectively. However, VOCs reactivity, in terms of OH loss rate, showed an indistinct statistical trend due to unsteady variations from naturally emitted isoprene, though some anthropogenic species showed decreasing trends, such as pentane, benzene and toluene. Meanwhile, daytime average O 3 increased rapidly at an annual rate of 2.6 ppbv yr −1 , around 5 % yr −1 between 2005 and 2011. Considering the influence of NO titration effect and elevated regional ozone background in the North China Plain (NCP), the main reason for such an increase in oxidants was subject to "local" photochemistry. A simplified model was used to evaluate the effect of changes in the levels of ozone precursors on ozone production. We found that between 2001 and 2006, the production rate of total oxidants, P (O x ) increased rapidly due to increased VOC levels and decreasing NO 2 , while from 2006 to 2011 P (O x ) re-mained high, though decreased slightly as a consequence of the decrease in both VOC reactivity (−5 % yr −1 ) and NO x (−4 % yr −1 ). Observations have shown that Beijing's efforts to control air pollution were somehow effective in cutting ozone precursors, but still left higher ground-level ozone. We surmised that it resulted from potential contributions from OVOCs and regional transport near Beijing. Therefore, Beijing needs deeper cooperation with adjacent provinces to control ozone pollution together. To impel this kind of joint prevention and control program, ground-level ozone should become a mandatory index for air quality management, and a faster reduction of VOCs, especially reactive VOCs, in urban areas, should coordinate with national NO x emission control programs.

Currently used aqueous electrolytes for lithium-ion batteries suffer from narrow potential windows of <1.5 V. In this paper, we are the first to discover the new deep eutectic solvent (DES) electrolyte of the methylsulfonylmethane–lithium perchlorate–water system, which is a safe, environmentally friendly, and low-cost “water-in-salt” aqueous electrolyte. It is found that the lithium ion can coordinate with the oxygen atom in the SO double bond, perchlorate, and water molecule, retaining fluidity at room temperature when the molar ratios of MSM:LiClO4:H2O are 1.8:1:z (z > 0.3). This DES electrolyte performs with a satisfying electrochemical stability window (∼3.5 V), which enables the LiMn2O4/Li4Ti5O12 aqueous lithium-ion battery with both high energy density (>160 W h kg–1) and high capacity retention (72.2% after 1000 cycles). Overall, our study of this new deep DES electrolyte can enrich room-temperature “water-in-salt” aqueous electrolyte and offers new insights into exploring green aqueous electrolyte systems for lithium-ion batteries.

Rechargeable batteries made from low-cost and abundant materials operating in safe aqueous electrolytes are attractive for large-scale energy storage. Sodium-ion battery is considered as a potential alternative of current lithium-ion battery. As sodium-intercalation compounds suitable for aqueous batteries are limited, we adopt a novel concept of Li+/Na+ mixed-ion electrolytes to create two batteries (LiMn2O4/Na0.22MnO2 and Na0.44MnO2/TiP2O7), which relies on two electrochemical processes. One involves Li+ insertion/extraction reaction, and the other mainly relates to Na+ extraction/insertion reaction. Two batteries exhibit specific energy of 17 Wh kg−1 and 25 Wh kg−1 based on the total weight of active electrode materials, respectively. As well, aqueous LiMn2O4/Na0.22MnO2 battery is capable of separating Li+ and Na+ due to its specific mechanism unlike the traditional “rocking-chair” lithium-ion batteries. Hence, the Li+/Na+ mixed-ion batteries offer promising applications in energy storage and Li+/Na+ separation.

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As existing battery technologies struggle to meet the requirements for widespread use in the field of large-scale energy storage, new concepts are urgently needed to build batteries with high energy density, low cost, and good safety. Here, we demonstrate two new aqueous batteries based on two monovalence metal ions (Li(+) /K(+) and Na(+) /K(+) ) as charge-transfer ions, Ni1 Zn1 HCF/TiP2 O7 and Ni1 Zn1 HCF/NaTi2 (PO4 )3 . These new batteries are unlike the conventional "rocking-chair" aqueous metal-ion batteries based on the migration of one type of shuttle ion between cathode and anode. They can deliver specific energy of 46 Wh kg(-1) and 53 Wh kg(-1) based on the total mass of active materials; this is superior to current aqueous battery systems based on sodium-ion and/or potassium-ion technologies. These two new batteries together with the previously developed Li(+) /Na(+) mixed-ion battery not only constitute a new battery family for energy storage, but also greatly broaden our horizons for battery research.

/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://dx.doi.org/10. 1016/j.electacta.2012.05.103 Electrochimica Acta, 77, pp. 212-224, 2012-06-09 Ordered alloy formation for Pt3Fe/C, PtFe/C and Pt5.75Fe5.75Cuy/CO2-reduction electro-catalysts Chen, L.; Bock, C.; Mercier, P. H. J.; Macdougall, B. R. alloy structure. The activity towards the orr was measured after 70 potential cycling, which can cause beneficial changes to the catalysts. In case of the specific orr activity, a dependence on the catalyst series is observed as follows:

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