Plastic waste is currently generated at a rate approaching 400 Mt year–1. The amount of plastics accumulating in the environment is growing rapidly, yet our understanding of its persistence is very limited. This Perspective summarizes the existing literature on environmental degradation rates and pathways for the major types of thermoplastic polymers. A metric to harmonize disparate types of measurements, the specific surface degradation rate (SSDR), is implemented and used to extrapolate half-lives. SSDR values cover a very wide range, with some of the variability arising due to degradation studies conducted in different natural environments. SSDRs for high density polyethylene (HDPE) in the marine environment range from practically 0 to approximately 11 μm year–1. This approach yields a number of interesting insights. Using a mean SSDR for HDPE in the marine environment, linear extrapolation leads to estimated half-lives ranging from 58 years (bottles) to 1200 years (pipes). For example, SSDRs for HDPE and polylactic acid (PLA) are surprisingly similar in the marine environment, although PLA degrades approximately 20 times faster than HDPE on land. Our study highlights the need for better experimental studies under well-defined reaction conditions, standardized reporting of rates, and methods to simulate polymer degradation using.

Over the last four decades, global plastics production has quadrupled 1 . Continuing this trend, the greenhouse gas (GHG) emissions from plastics would reach 15% of the global carbon budget by 2050 2 . Strategies to mitigate the life cycle GHG emissions of plastics, however, have not been evaluated on a global scale. Here, we compile a new dataset covering ten conventional and five bio-based plastics and their life cycle GHG emissions under various mitigation strategies. Our results show that the global life cycle GHG emissions of conventional plastics was 1.7 Gt CO 2 e in 2015, which would grow to 6.5 Gt CO 2 e by 2050 under the current trajectory.However, an aggressive application of renewable energy, recycling, and demand management strategies in concert has the potential to keep the 2050 emissions comparable to the 2015 level. In addition, replacing fossil feedstock by biomass can further reduce the emissions to achieve an absolute reduction from the current level. Our study demonstrates the need for integrating energy, materials, recycling, and demand management strategies to curb the growing life cycle GHG emissions from plastics. MainGlobal production of plastics grew from 2 Mt to 380 Mt between 1950 and 2015, at a compound annual growth rate (CAGR) of 8.4% 1 . Globally, 58% of plastic waste was discarded or landfilled, and only 18% was recycled in 2015 1 . It is estimated that 4.8-12.7 Mt plastic waste generated by coastal countries entered the ocean in 2010 3 .Growing along the volume of global production and consumption of plastics are the diverse concerns on their impacts to the ecosystem and human health [4][5][6][7] . However, 2 relatively little attention has been paid to their contributions to climate change.While the chemical industry as a whole is responsible for about 15% of global anthropogenic greenhouse gas (GHG) emissions 8 , the magnitude of global life cycle GHG emissions from plastics has yet to be quantified.Various strategies to reduce GHG emissions from plastics have been discussed in the literature. Replacing fossil-based plastics by bio-based plastics, for example, is one of them [9][10][11] . Bio-based plastics generally show lower life cycle GHG emissions compared to fossil-based counterparts 12 . Substituting 65.8% of the world's conventional plastics with bio-based plastics is estimated to avoid 241 to 316 Mt CO2e per year 13 . Both biodegradable and non-biodegradable forms of bio-based plastics are available in the market 14 . Bio-based non-biodegradable polymers such as Bio-Polyethylene (Bio-PE) and Bio-Polyethylene Terephthalate (Bio-PET), also referred to "drop-in" polymers, offer virtually identical properties with their fossilbased counterparts. While bio-based biodegradable polymers, such as Polylactic Acid (PLA), Polyhydroxyalkanoates (PHAs) and Thermoplastic Starch (TPS) display somewhat different mechanical and chemical properties 12 . Strategies to promote bio-based plastics have been initiated by the European Commission and other countries including Japan, Korea and T...

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In this work, a facile approach was successfully developed for in situ catalyzing Au nanoparticles loaded on Fe3O4@SiO2 magnetic nanospheres via Sn(2+) linkage and reduction. After the Fe3O4@SiO2 MNPs were first prepared via a sol-gel process, only one step was needed to synthesize the Fe3O4@SiO2-Au magnetic nanocomposites (Fe3O4@SiO2-Au MNCs), so that both the synthesis step and the reaction cost were remarkably decreased. Significantly, the as-synthesized Fe3O4@SiO2-Au MNCs showed high performance in the catalytic reduction of 4-nitrophenol to 4-aminophenol and could be reused for several cycles with convenient magnetic separability. This approach provided a useful platform based on Fe3O4@SiO2 MNPs for the fabrication of Au or other noble metal magnetic nanocatalysts, which would be very useful in various catalytic reductions.

Antimony chalcogenides are widely studied as a light-absorbing material due to their merits of low toxicity, efficient cost, and excellent photovoltaic properties. However, the band gaps of antimony selenide (approximately 1.1 eV) and antimony sulfide (approximately 1.7 eV) both deviate from the optimal detailed balance band gap (∼1.3 eV) for terrestrial single-junction solar cells. Notably, the band gap of Sb 2 (S, Se) 3 can be tunable in the range from 1.1 to 1.7 eV, which can cover the detailed balance band gap. In this work, the vapor transport deposition method with two independent evaporation sources is used to deposit Sb 2 (S, Se) 3 thin films. By carefully optimizing the evaporation temperature and the start evaporation time of the Sb 2 Se 3 and Sb 2 S 3 sources, a suitable band gap of 1.33 eV is obtained. Finally, on the basis of the optimal Sb 2 (S, Se) 3 films, Sb 2 (S, Se) 3 solar cells without a hole transport layer achieved an efficiency of 7.03%.