NH2-MIL-125(Ti) encapsulated with in situ-formed carbon nanodots with up-conversion effect for improving photocatalytic NO removal and H2 evolution

The bifunctional photocatalyst CDs@NH2-MIL-125(Ti), carbon nanodots (CDs) encapsulated in NH2-MIL-125 (Ti), was constructed in situ by a simple and convenient low-temperature calcination approach, which exhibited great capacity in NO removal (at air level) and H2 evolution simultaneously under visible-light irradiation. The NO removal rate of CDs@NH2-MIL-125(Ti) (10 mM) reached 53%, which was 28.4% higher than pristine NH2MIL-125(Ti). Moreover, the H2 production rate was 5820.95 mu mol g-1, which was 5.34 times higher than that of original NH2-MIL-125(Ti). The corresponding optical and electrical performances of CDs@NH2-MIL-125(Ti) characterized by UV-Vis, UCPL, ESR, and in situ DRIFTS, etc. indicated that the encapsulated CDs uniformly dispersed in the pores of NH2-MIL-125(Ti) could improve the visible light utilization via the up-conversion effect and photosensitization, and serve as an electron-receiver to significantly prolong the lifetime of the photogenerated charge carriers, thus enhancing the photocatalytic performance. The results revealed that fabricating CDs with metal-organic frameworks (MOFs) could be an available strategy for us to boost the photocatalytic NO elimination and H2 evolution activity simultaneously.

双功能光催化剂CDs@NH₂ - MIL - 125(Ti)，即碳纳米点（CDs）封装在NH₂ - MIL - 125(Ti)中，通过一种简便的低温煅烧方法原位制备而成，在可见光照射下同时在NO去除（大气水平）和H₂析出方面表现出强大的能力。CDs@NH₂ - MIL - 125(Ti)（10 mM）的NO去除率达到53%，比原始的NH₂ - MIL - 125(Ti)高28.4%。此外，H₂产率为5820.95 μmol g⁻¹，是原始NH₂ - MIL - 125(Ti)的5.34倍。通过紫外 - 可见光谱（UV - Vis）、上转换光致发光光谱（UCPL）、电子自旋共振（ESR）和原位漫反射红外光谱（in situ DRIFTS）等对CDs@NH₂ - MIL - 125(Ti)进行表征的相应光学和电学性能表明，均匀分散在NH₂ - MIL - 125(Ti)孔隙中的封装CDs可通过上转换效应和光敏化提高可见光利用率，并作为电子受体显著延长光生载流子的寿命，从而提高光催化性能。结果表明，将碳纳米点与金属 - 有机框架（MOFs）复合可能是一种同时提高光催化NO去除和H₂析出活性的有效策略。