Ru单原子负载g-C3N4催化剂的制备及其光催化固氮性能研究

采用固相原位还原法成功合成了负载钌(Ru)单原子的石墨相氮化碳(g-C₃N₄)催化剂。研究结果表明,Ru以单原子形式分散在g-C₃N₄材料表面上,Ru的负载使g-C₃N₄的3-s-三嗪单元结构的有序度降低,通过傅里叶变换红外吸收光谱(FTIR)测试分析可知催化剂中含有氰基,氰基导致了分子结构缺陷。Ru和氰基均为电子受体,可加速光生电子的转移并作为催化活性位点。负载Ru单原子后,g-C₃N₄的光吸收范围变宽,光吸收强度增强,使得Ru单原子负载g-C₃N₄具有良好的光催化活性,光催化固氮效率高达113.23μg·g^-1 cat·h-1,是单相g-C₃N₄催化剂的2.7倍。同时,Ru原子负载的g-C₃N₄还显示出很好的稳定性,经5次循环实验后光催化固氮效率仍能维持在106.75μg·g^-1 cat·h^-1。此外,通过光致发光光谱(PL)、电化学阻抗谱(EIS)等表征手段探究了Ru单原子g-C₃N₄的光催化固氮机理,其中氮气、超纯水和光照是使催化剂发挥光催化固氮作用的必要条件。

Ruthenium Single Atoms Supported on Graphitic Carbon Nitride for Nitrogen Photofixation

A catalyst of graphitic carbon nitride(g-C₃N₄)loaded with ruthenium(Ru)single atoms was synthesized by the method of solid phase in-situ reduction successfully.The results showed that Ru was dispersed on the surface of g-C₃N₄ as single atoms,and the loading of Ru reduced in-plane repeating units of g-C₃N₄.Through the analysis of FTIR,it was found that there were cyano groups in the catalyst,which led to the molecular structural defect.Both Ru atoms and cyano groups were electron acceptors,which could accelerate the transfer of photogenerated electrons and acted as photocatalytic active sites.After loading with Ru atoms,the light absorption range of g-C₃N₄ was widened and the absorption intensity was enhanced.Thus,the catalyst had excellent activity.Its photocatalytic nitrogen fixation efficiency was as high as 113.23μg·g^-1 cat·h^-1,2.7 times that of the bare g-C₃N₄ catalyst.Meanwhile,the catalyst of g-C₃N₄ supported by Ru atoms also showed good stability,and the photocatalytic nitrogen fixation efficiency remained at 106.75μg·g^-1 cat·h-1 after five cycles.In addition,the photocatalytic nitrogen fixation mechanism of the catalyst was investigated by PL,EIS and other characterization methods,in which nitrogen,ultrapure water and illumination were necessary conditions for the photocatalytic nitrogen fixation of the catalyst.