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

Abstract

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 N2 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 µmol g−1 h−1 (with H2O as the proton source) and 84.00 µmol 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 N2 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 N2 conversion to NH3 through a Gibbs free energy release leading alternating pathway with a low energy barriers, on the oxygen vacancy on TiO2 surface.

Altering Hydrogenation Pathways in Photocatalytic Nitrogen Fixation by Tuning Local Electronic Structure of Oxygen Vacancy with Dopant

“…Thec atalytic behavior involving reaction pathways is,t o agreat extent, determined by the local electronic structure of catalytic sites.I nt erms of controlling catalytic sites,o xygen vacancies have been extensively investigated for oxide catalysts in catalytic nitrogen reduction, [4][5][6][7][8][9][10][11] highlighting their importance as catalytic sites.F or this reason, we focus on the surface oxygen vacancies using titanium dioxide (TiO 2 )a s acatalyst model, and aim to elucidate the mystery how their local electronic structure impacts on reaction pathways.T o modulate the local electronic structure of oxygen vacancies, we decide to adopt the strategy of doping heteroatoms that has been proven as as imple and effective way toward such ap urpose. [10,[12][13][14] Another noteworthy advantage for heteroatom doping is to improve the stability of catalysts containing oxygen vacancies.I nm ost cases,o xygen vacancies are created via annealing in ah igh-temperature and oxygen-deficient atmosphere; [15] however, they generally tend to recombine with oxygen and disappear once exposed to air at room temperature, [16] which would severely impede our investigation on the local electronic structure of oxygen vacancies.Such alimitation can be overcome when we choose to create local oxygen vacancies by introducing heteroatoms during the synthesis process.T he heteroatoms on the surface can serve as charge-compensating species to accept electrons and thus effectively stabilize oxygen vacancies.A ss uch, heteroatom doping can provide an excellent platform for investigating the role of dopants in modulating the local electronic structure and the impact of local electronic structure adjacent to oxygen vacancyo nt he hydrogenation pathways in photocatalytic nitrogen fixation, which remain unexplored in the past research for oxygen vacancy-induced NRR.…”

Metal Carbide‐Based Cocatalysts for Photocatalytic Solar‐to‐Fuel Conversion

“…More importantly, carburization not only improves electron mobility but also alters the Fermi level of [193] Copyrights 2020, American Chemical Society. [191] Ti 3 C 2 TiO 2 None Nessler's reagent 422 2020 [238] Ti 3 C 2 N-doped TiO 2 Methanol Nessler's reagent 415.6 2021 [239] Ti 3 C 2 Co-doped TiO 2 None Nessler's reagent 110 2020 [240] Ti 3 C 2 P25 None Ion chromatography 10.74 2020 [241] Ti 3 C 2 Bi 4 O 5 Br 2 None Nessler's reagent 277.74 2021 [242] Ti 3 C 2 CdS nanorod Methanol Nessler's reagent 293.06 2020 [192] Ti 3 C 2 N-defect g-C 3 N 4 Methanol Nessler's reagent 5792 2020 [243] Ti 3 C 2 -QDs Ni-MOF Na 2 SO 3 Nessler's reagent 88.79 2020 [193] RuO 2 /Ti 3 C 2 TiO 2 None Indophenol blue 56.7 2020 [244] Nb 2 O 5 /C/Nb 2 C g -C 3 N 4 Methanol Nessler's reagent 365 2020 [245] MXene-derived TiO 2 @C g-C 3 N 4 Methanol Nessler's reagent 205.6 2018 [246] MXene-derived carbon MXene-derived TiO 2 Methanol Indophenol blue or Nessler's reagent 84 2021 [247] metal carbides. On the other hand, the construction of new metal carbide-based cocatalysts with excellent electronic properties, such as excellent charge-extracting/electron-capturing capability and optimized adsorption and desorption energy of intermediates, is also crucial for boosting photocatalytic activity and selectivity.…”

Investigating the role of oxygen vacancies in metal oxide for enhanced electrochemical reduction of NO3− to NH3: mechanistic insights

“…Similarly, OV-C/TiO 2 samples were synthesized by Qian et al 130 by subjecting Ti 3 C 2 MXene, serving as the precursor, to a single calcination step (Fig. 8d).…”