Photocatalytic Nitrogen Reduction by Ti3C2 MXene Derived Oxygen Vacancy-Rich C/TiO2

摘要

In this work, oxygen vacancy-rich C/TiO2 (OV-C/TiO2) samples are prepared by a one-step calcination approach using Ti3C2 MXene as the precursor, and used for the photocatalytic N-2 reduction. The NH3 yields of all the prepared OV-C/TiO2 samples exceed those achieved on commercial anatase TiO2 and P25, with both H2O and CH3OH as the proton sources. Among them, the OV-C/TiO2-600 offers the remarkable NH3 synthesis rates, which are 41.00 mu mol g(-1) h(-1) (with H2O as the proton source) and 84.00 mu mol g(-1) h(-1) (with CH3OH as the proton source). The photocurrent and fluorescence spectra show that OV-C/TiO2-600 exhibit the highest generation/separation rate and longest lifetime of photocarriers among all the prepared samples. ESR and TPD experiments confirm much more efficient chemisoption of N-2 on the surface of the prepared OV-C/TiO2-600 than that on the surface of the commercial anatase TiO2. Moreover, DFT calculations further demonstrate that N-2 conversion to NH3 through a Gibbs free energy release leading alternating pathway with a low energy barriers, on the oxygen vacancy on TiO2 surface.