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[Display omitted] • A new-type porous carbon-supported LiFePO 4 electrode was prepared. • In-situ polymerization and synchronous conversion method was developed. • High hydrophilicity, stability and electrochemical performance were obtained. • The intercalation capacity was nearly twice that of the traditional electrode. Electrochemical method is a green lithium extraction method, but this technology is limited by the stability and capacity of the electrodes. Herein, a new strategy for the preparation of highly stable and high-capacity electrodes by in-situ polymerization and synchronous conversion was developed. It was found that when resorcinol and formaldehyde containing soluble Li, Fe, and P sources were polymerized in-situ and then carbonized at 700 °C, the Li, Fe, and P sources were successfully converted into LiFePO 4 and uniformly dispersed in the carbon matrix. The carbon in the material formed a three-dimensional (3D) skeleton in the form of interconnected carbon spheres, and the LiFePO 4 was grown in-situ on the 3D carbon skeleton. Since no polymer binder was used, the electrode exhibited high hydrophilicity and stability. Especially, the unique hierarchical porous structure of the electrode makes it have high electrochemical and lithium extraction performance. Even for Li+ with a concentration of only 100 mg·L−1, the intercalation capacity reached 5.13 mg·cm−3, which was nearly twice that of the electrode prepared by the traditional method. The equilibrium time for Li+ intercalation was only 45 min, and the dissolution loss rate of Fe3+ was no more than 0.23 % after 50 CV cycles. Based on these excellent properties, the porous carbon-supported LiFePO 4 electrode prepared will has a broad application prospect for lithium recovery from aqueous solutions by the green electrochemical technology, and the preparation strategy developed in this work also provides a new prospective for the preparation of high-performance lithium extraction electrodes. [ABSTRACT FROM AUTHOR]

Satellite remote sensing is an important technique providing long-term and large-scale information of formaldehyde (HCHO), which plays a crucial role in atmospheric chemistry. Low signal-to-noise ratio and poor stability of the Environmental Trace Gases Monitoring Instrument (EMI) On board Gaofen-5 satellite, the first Chinese space-borne spectrometer, make HCHO retrieval extremely difficult. Here we firstly retrieved HCHO vertical column densities (VCDs) from EMI through in-flight spectral calibration, retrieval setting optimization and stripe correction. Retrieved EMI HCHO VCDs correlate well with those measured by Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) with normalize mean bias (NMB) below 25%. EMI HCHO VCDs are comparable with those observed by Ozone Monitoring Instrument (OMI) and TROPOspheric Monitoring Instrument (TROPOMI). This study reveals that HCHO can be observed successfully by algorithm optimization despite of poor performance of space-borne spectrometer. The retrieved EMI HCHO VCDs are applied to locate emission sources of volatile organic compounds (VOCs). • First retrieval of HCHO from Environmental Trace Gases Monitoring Instrument (EMI). • Algorithm optimization is proposed suitable for EMI HCHO retrieval. • HCHO vertical column density (VCD) correlates well with ground-based measurements. • EMI HCHO measurements are improved to a comparable level with OMI measurements. • HCHO hotspots and source of volatile organic compounds are captured successfully by EMI. [ABSTRACT FROM AUTHOR]

Atmospheric formaldehyde (HCHO) is considered as one of significant oxidization intermediate of most volatile organic compounds (VOCs). Previous studies using HCHO/NO 2 ratio for ozone formation sensitivity are based on the hypothesis that HCHO is a reliable indicator for total VOC reactivity (VOCR), while few studies focused on evaluating this hypothesis. To reassess this assumption, three fitting methods have been proposed for correlation analysis between the HCHO and VOCR, showing the Pearson correlation coefficient increased in the following order: logarithmic fitting < linear fitting < exponential fitting. Near-surface HCHO VMRs and the exponent-transformed VOCR showed good agreement during the entire daytime, indicating that HCHO concentrations primarily depend on VOCR, especially at midday and afternoon. High correlation coefficients are not only found between the HCHO and VOCR, but also between the HCHO and ozone formation potential (OFP), implying that HCHO is strongly influenced by the photochemical oxidation of VOCs and closely linked to ozone formation. Furthermore, good consistencies were exhibited between TROPOMI HCHO VCDs and the calculated photochemical property parameters of NMHCs (e.g., Total NMHCs, VOCR, and OFP), suggesting that satellite-based HCHO columns can infer the VOCs emissions over large spatial areas. We also make an attempt to convert the concentration of HCHO to total Prop-equiv concentration of NMHCs based on the linear regression analysis method, which overestimates the measured values by about 16%. Our findings imply that HCHO has the feasibility being a proxy for VOCs, which also indirectly proves the reasonability of HCHO/NO 2 ratio to indicate ozone sensitivity. [Display omitted] • HCHO concentrations primarily depend on VOCR especially at midday and afternoon. • Good consistency is found between the HCHO and ozone formation potential. • Ambient HCHO has the ability being a proxy for total NMHCs. • TROPOMI HCHO VCDs has the ability to infer the VOCs emissions. [ABSTRACT FROM AUTHOR]

Ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) observations were performed from 27 December 2018 to 16 January 2019 in Changshou, one of subdistricts of Chongqing, China. Primary atmospheric pollutant in Changshou during wintertime was PM 2.5 , whose contribution averaged about 70.15% ± 9.5% of PM 10. The ratio of PM 2.5 /PM 10 decreased when PM 2.5 pollution became worse, and it should attribute to biomass burning and the contribution of hygroscopic growth and enhanced heterogeneous chemistry under high relative humidity condition. Moreover, nitrogen dioxide (NO 2), formaldehyde (HCHO) and glyoxal (CHOCHO) vertical profiles during the campaign period were retrieved separately. TROPOMI HCHO vertical column densities (VCDs) and MAX-DOAS HCHO VCDs were correlated well (R = 0.93). In order to identify the sources of volatile organic compound (VOC) in Changshou, the ratio of CHOCHO to HCHO (R GF) in five different layers were estimated. The estimated daily averaged R GF were 0.0205 ± 0.0077, 0.0727 ± 0.0286, 0.0864 ± 0.0296, 0.0770 ± 0.0275 and 0.0746 ± 0.0263 in 0–100 m, 100–200 m, 300–400 m, 500–600 m and 700–800 m layers, respectively. The estimated R GF will increase when biomass burnings were dominated. Using NO 2 as a tracer of anthropogenic emissions, we found the R GF values gradually decrease with the increase of NO 2 levels. R GF values in 0–100 m layer and all the other upper layers are 0.015–0.025 and 0.06–0.14, and that means the dominant sources of VOCs in 0–100 m layer and all the other upper layers are biogenic emission and anthropogenic emission (especially biomass burning), respectively. In addition, we found that R GF has site dependence which is in compliance with several previous studies. Unlabelled Image • The ratio of PM 2.5 /PM 10 decreased when PM 2.5 pollution became worse • HCHO and CHCOHO mainly distributed in 0-100 m and 100-200 m, respectively. • The sources of VOCs above 100 m are mainly from biomass burning. [ABSTRACT FROM AUTHOR]