The non-metal organic polymers have attracted increasing attentions in the photocatalysis field because of their low cost, metal-free, visible-light responsive, easy preparation and high stability. Herein, metal-free (SCN)_n polymers with various polymerization degrees were prepared by a facile, low cost and environmentally friendly grinding method and presented excellent visible-light photocatalytic performance for organic pollutants degradation and Cr(VI) reduction. Owing to their π conjugated structure, all the as-prepared (SCN)_n polymers exhibited excellent visible-light absorption properties up to 550 nm, which were much better than that of bulk g-C₃N₄. Furthermore, both experiments and theoretical calculations unveiled that the peculiar chain structure, LUMO potential, charge separation and molecular oxygen motivation of (SCN)_n polymers could be adjusted by tuning the polymerization degrees of samples. Therefore, the photocatalytic properties of (SCN)_n polymers could be significantly improved by optimizing the polymerization degrees of samples. Besides, the possible photocatalytic degradation pathways of antibiotic Tetracycline (TC) over (SCN)_n polymer was also studied based on liquid chromatography-tandem mass spectrometry (LC-MS) analysis. The developed metal-free (SCN)_n polymer in this work proposed new thinking for the photocatalysis in water purification.

非金属有机聚合物由于其低成本，无金属，对可见光敏感，易于制备和高稳定性而在光催化领域引起了越来越多的关注。本文中，通过简便，低成本和环保的研磨方法制备了具有各种聚合度的无金属（SCN）_n聚合物，该聚合物具有出色的可见光光催化性能，可降解有机污染物和还原Cr（VI）。由于它们的π共轭结构，所有制备的（SCN）_n聚合物在550 nm处均表现出优异的可见光吸收性能，远优于块状gC ₃ N _4。。此外，实验和理论计算均表明，可以通过调节样品的聚合度来调节（SCN）_n聚合物的特殊链结构，LUMO势，电荷分离和分子氧动机。因此，通过优化样品的聚合度可以显着提高（SCN）_n聚合物的光催化性能。此外，还基于液相色谱-串联质谱法（LC-MS）分析了抗生素四环素（TC）在（SCN）_n聚合物上的可能的光催化降解途径。这项工作中开发的无金属（SCN）_n聚合物为水净化中的光催化作用提出了新的思路。