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

[Display omitted] •A novel bifunctional catalyst CDs@NH2-MIL-125(Ti) was obtained in a convenient approach.•The catalyst can simultaneously achieve NO removal and hydrogen evolution.•The catalyst exhibited excellent photocatalytic performance under visible light.•The up-conversion effect of CDs can improve the utilization of light energy effectively.•The in-situ DRIFTS spectra were used to analyze intermediates during the NO removal. 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 NH2-MIL-125(Ti). Moreover, the H2 production rate was 5820.95 μmol 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.