Postconsumer plastics are generally perceived as valueless with only a small portion of plastic waste being closed-loop recycled into similar products while most of them are discarded in landfills. Depositing plastic waste in landfills not only harms the environment but also signifies a substantial economic loss. Alternatively, constructing value-added chemical feedstocks via mining the waste-derived intermediate species as a carbon (C) source under mild electrochemical conditions is a sustainable strategy to realize the circular economy. This proof-of-concept work provides an attractive “turning trash to treasure” strategy by integrating electrocatalytic polyethylene terephthalate (PET) plastic upcycling with a chemical C–S coupling reaction to synthesize organosulfur compounds, hydroxymethanesulfonate (HMS). HMS can be produced efficiently (Faradaic efficiency, FE of ∼70%) via deliberately capturing electrophilic intermediates generated in the PET monomer (ethylene glycol, EG) upcycling process, followed by coupling them with nucleophilic sulfur (S) species (i.e., SO₃^2– and HSO₃^–). Unlike many previous studies conducted under alkaline conditions, PET upcycling was performed over an amorphous MnO₂ catalyst under near-neutral conditions, allowing for the stabilization of electrophilic intermediates. The compatibility of this strategy was further investigated by employing biomass-derived compounds as substrates. Moreover, comparable HMS yields can be achieved with real-world PET plastics, showing its enormous potential in practical application. Lastly, Density function theory (DFT) calculation reveals that the C–C cleavage step of EG is the rate-determining step (RDS), and amorphous MnO₂ significantly decreases the energy barriers for both RDS and C–S coupling when compared to the crystalline counterpart.

中文翻译：

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挖掘塑料垃圾升级回收中的碳中间体构建C-S键


消费后塑料通常被认为毫无价值，只有一小部分塑料废物被闭环回收成类似产品，而大多数则被丢弃在垃圾填埋场。将塑料废物存放在垃圾填埋场不仅危害环境，而且还意味着巨大的经济损失。或者，通过在温和的电化学条件下开采废物衍生的中间物质作为碳（C）源来构建增值化学原料是实现循环经济的可持续策略。这项概念验证工作通过将电催化聚对苯二甲酸乙二醇酯 (PET) 塑料升级回收与化学 C-S 偶联反应相结合来合成有机硫化合物羟基甲磺酸 (HMS)，提供了一种有吸引力的“变废为宝”策略。通过故意捕获 PET 单体（乙二醇，EG）升级过程中产生的亲电子中间体，然后将它们与亲核硫 (S) 物质（即 SO ₃ ^2–和 HSO ₃ ^– )。与之前在碱性条件下进行的许多研究不同，PET升级回收是在接近中性条件下在无定形MnO ₂催化剂上进行的，从而实现了亲电中间体的稳定。通过使用生物质衍生的化合物作为底物，进一步研究了该策略的兼容性。此外，现实世界中的 PET 塑料也能实现与 HMS 相当的产量，显示出其在实际应用中的巨大潜力。 最后，密度函数理论（DFT）计算表明，EG的C-C裂解步骤是速率决定步骤（RDS），与非晶态MnO 2 相比，非晶态MnO ₂显着降低了RDS和C-S耦合的能垒。结晶对应物。