Construction of 3D N-CQD/MOF-5 photocatalyst to improve the photocatalytic performance of MOF-5 by changing the electron transfer path

MOF-5 is an emerging semiconductor material with a great potential in photocatalytic wastewater treatment. However, its inherent deficiencies, such as the narrow range of photo-response, the fast recombination of photoinduced carriers and the unstable structure, largely limit its further application. In this work, super biocompatible N-doped carbon quantum dots (N-CQD) derived from the green precursor, coconut shells, were in situ grown on MOF-5 via a facile solvothermal method to construction of 0D/3D N-CQD/MOF-5 photocatalyst with an enhanced photoreduction ability. A sustainable and pollution-free preparation process of N-CQD/MOF-5 photocatalyst was delivered and biomass waste resource was effectively utilized via this method. This well designed photocatalyst with the optimized 1% N-CQD loading presented a considerable photoreduction rate of Cr (VI), which was 2.5 times higher that of pure MOF-5. It also possessed a strong structural stability and reusability even after multiple tests. The boosting photocatalysis activity could be attributed to the doping of NCQD, who not only act as an electron acceptor to separate the photoexcited electrons and holes effectively, but also play a vital role as a photosensitizer to improve the visible-light absorption. Furthermore, the influence of activation methods on the photocatalytic activity of MOF-5 were also investigated theoretically. For the purpose of clarifying the potentially photocatalytic mechanism of N-CQD/MOF-5 in photoreduction Cr (VI), a series of tests involving photoelectrical characterizations and fluorescence spectroscopy were executed. Therefore, this study provides an innovative photocatalytic system for an enhanced photoreduction performance of Cr (VI) of MOF-5.

Automated summary

The N-CQD/MOF-5 photocatalyst, constructed by growing super biocompatible N-doped carbon quantum dots on MOF-5 derived from coconut shells, showed enhanced photoreduction ability and structural stability. The optimized 1% N-CQD loading resulted in a considerable increase in the photoreduction rate of Cr (VI) compared to pure MOF-5, demonstrating the potential for improved wastewater treatment applications.