Microplastics (MPs) have frequently been found in the environment. However, studies of the quantification methods for MPs are still needed. Plastics are polymers with different degrees of polymerization. In this study, alkali-assisted thermal hydrolysis was applied to depolymerize two plastics containing ester groups, polycarbonate (PC) and polyethylene terephthalate (PET), in a pentanol or butanol system. By determining the concentrations of the depolymerized building block compounds, i.e., bisphenol A and p-phthalic acid, we quantified the amounts of PC and PET MPs in environmental samples. Recoveries of 87.2−97.1% were obtained for the PC and PET plastic particles spiked in the landfill sludge. The method was successfully applied to determine the occurrence of PC and PET MPs in samples of sludge, marine sediments, indoor dust, digestive residues in mussel and clam, and sea salt and rock salt. High concentrations of 246 and 430 mg/kg were determined for PC and PET type MPs, respectively, in an indoor dust. In addition, concentrations of 63.7 mg/kg for PC and 127 mg/kg for PET were detected in the digestive residues of a clam.

Despite the major improvements in device efficiency, perovskite solar cells (PSCs) are limited by their poor stability due to the degradation toward moisture. Recently studies have demonstrated that the perovskite materials can be stabilized by adding more inorganic elements such as Cs and Rb. However, the specific mechanism is not yet fully established. In this paper, first-principles calculations were employed to investigate the effects of Rb incorporation and water degradation on cubic formamidinium lead iodide (FAPbI3) perovskite. The termination dependence of the structural stability of the representative (100), (010), and (001) surfaces was characterized by surface energies. The PbI2-terminated (001) surface was found to be the most stable surface structure. The Rb dopants were found to be energetically favorable, existing on the surface more than staying in the inner atomic layers. Furthermore, the degradation mechanism was investigated by water adsorption on the Rb-incorporated FAPbI3 (001) surface. According to our calculations, the water molecules tend to interact with the surface on the Pb-top sites with the largest adsorption energy. The orientation of the surface FA cations exerted a crucial influence on the adsorption energy as well as the surface energy. The moisture-induced decrease in optical absorption in the visible region could be observed in absorption spectra. It indicates that the adsorbed water molecules subsequently reduce the conversion efficiency. More importantly, we find that Rb incorporation at the surface region with the largest adsorption energy will destroy the surface structure leading to the obvious drop in the absorption spectra. These findings further illustrate the initial degradation process of Rb-incorporated FAPbI3 under the humid condition, which should be helpful to improve the stability of Rb-doped FAPbI3 perovskites in the presence of moisture.

Three-dimensional (3D) structures of V10O24·12H2O nanosheets coated with carbon (denoted as V10O24@C) are facially and cost-effectively fabricated by reducing the V2O5-based aqueous solution with ethanol under hydrothermal conditions. By using the 3D V10O24@C as the cathode of zinc-ion batteries, the as-obtained 3D V10O24@C sample delivers excellent charge–discharge cycling capability, superior rate performance, and reasonable specific capacity, and a specific capacity of ca. 133.3 mA h g–1 and a 94.1% capacity retention are achieved even after 10000 cycles at a high current density of 10 A g–1 (∼80 C). Furthermore, it provides a facile and scalable approach to synthesize the 3D structures of pure-phased vanadium oxide nanosheets or other nanoscale metal oxides coated with carbon.

Air quality in Northern China has become a global hot spot issue due to a series of air pollution events in the recent years. In this study, five representative air pollutants (PM 2.5 , SO 2 , NO 2 , CO, and O 3 ) were employed to reveal the spatial and temporal distribution of air pollution in Northern China. Periodic decline in PM 2.5 , SO 2 , CO, and NO 2 from 2016 to 2018 indicated that air pollution control measures have achieved desired results. In addition, PM2.5 was significantly positively correlated with SO 2 , CO, and NO 2 (p < 0.001), and O 3 had negative correlations with the other four pollutants. Furthermore, the heavy pollution phenomenon in Shijiazhuang, Anyang, Xingtai, and Handan was attributed to their industrial structures (e.g., steel industry) and geographical location based on clustering analysis. Contrary to above four pollutants, the annual average concentrations of O 3 increased in all the nine cities (1.4-35.9%) from 2016 to 2018. It is necessary to plan mitigation strategy for O 3 based on further investigation of source and formation mechanism of O 3 .Plain Language Summary Air pollution in Northern China has attracted many attentions due to continuous air pollution issues in the recent years. However, few studies focused on air pollution in the Beijing-Tianjin-Hebei transmission corridor. In this study, the spatiotemporal variation of air pollutants in nine typical cities was investigated. Pearson correlation analysis and clustering analysis were employed to analyze their relationship and reveal the pollution characteristic and the factors affecting the air pollution. This study provided an insight for the prevention and control of air pollution in Northern China.

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