Wu Yue, Nguyen Phuc T T, Wong Sie Shing, Feng Minjun, Han Peijie, Yao Bingqing, He Qian, Sum Tze Chien, Zhang Tianyong, Yan Ning
Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117585, Singapore, Singapore.
Tianjin Key Laboratory of Applied Catalysis Science and Technology, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300354, People's Republic of China.
Nat Commun. 2025 Jan 20;16(1):846. doi: 10.1038/s41467-025-55930-x.
Photocatalytic conversion has emerged as a promising strategy for harnessing renewable solar energy in the valorization of plastic waste. However, research on the photocatalytic transformation of plastics into valuable nitrogen-containing chemicals remains limited. In this study, we present a visible-light-driven pathway for the conversion of polylactic acid (PLA) into alanine under mild conditions. This process is catalyzed by defect-engineered CdS nanocrystals synthesized at room temperature. We observe a distinctive volcano-shaped relationship between sulfur vacancy content in CdS and the corresponding alanine production rate reaching up to 4.95 mmol/g catalyst/h at 70 C. Ultraviolet-visible, photocurrent, electrochemical impedance, transient absorption, photoluminescence, and Fourier-transform infrared spectroscopy collectively highlight the crucial role of sulfur vacancies. The surface vacancies serve as adsorption sites for lactic acid; however, an excessive number of vacancies can hinder charge transfer efficiency. Sulfur vacancy-rich CdS exhibits high stability with maintained performance and morphology over several runs, effectively converts real-life PLA products and shows potential in the amination of other polyesters. This work not only highlights a facile approach for fabricating defect-engineered catalysts but also presents a sustainable method for upcycling plastic waste into valuable chemicals.
光催化转化已成为一种在塑料废物增值过程中利用可再生太阳能的有前景的策略。然而，关于将塑料光催化转化为有价值的含氮化学品的研究仍然有限。在本研究中，我们展示了一条在温和条件下将聚乳酸（PLA）转化为丙氨酸的可见光驱动途径。该过程由室温合成的缺陷工程化硫化镉纳米晶体催化。我们观察到硫化镉中的硫空位含量与相应的丙氨酸产率之间存在独特的火山形关系，在70℃时丙氨酸产率高达4.95 mmol/g催化剂/小时。紫外可见光谱、光电流、电化学阻抗、瞬态吸收、光致发光和傅里叶变换红外光谱共同突出了硫空位的关键作用。表面空位作为乳酸的吸附位点；然而，过多的空位会阻碍电荷转移效率。富含硫空位的硫化镉在多次运行中表现出高稳定性，性能和形态保持不变，能有效转化实际的聚乳酸产品，并在其他聚酯的胺化反应中显示出潜力。这项工作不仅突出了一种制备缺陷工程化催化剂的简便方法，还提出了一种将塑料废物升级循环为有价值化学品的可持续方法。
