High-density frustrated Lewis pairs based on Lamellar Nb2O5 for photocatalytic non-oxidative methane coupling

Abstract

Photocatalytic methane conversion requires a strong polarization environment composed of abundant activation sites with the robust stretching ability for C-H scissoring. High-density frustrated Lewis pairs consisting of low-valence Lewis acid Nb and Lewis base Nb-OH are fabricated on lamellar Nb2O5 through a thermal-reduction promoted phase-transition process. Benefitting from the planar atomic arrangement of lamellar Nb2O5, the frustrated Lewis pairs sites are highly exposed and accessible to reactants, which results in a superior methane conversion rate of 1456 μmol g−1 h−1 for photocatalytic non-oxidative methane coupling without the assistance of noble metals. The time-dependent DFT calculation demonstrates the photo-induced electron transfer from LA to LB sites enhances their intensities in a concerted way, promoting the C-H cleavage through the coupling of LA and LB. This work provides in-depth insight into designing and constructing a polarization micro-environment for photocatalytic C-H activation of methane without the assistance of noble metals.

Highly Selective Photocatalytic Methane Coupling by Au-Modified Bi2WO6

“…The photocatalytic OCM activity of the as-synthesized photocatalysts was evaluated using a homebuilt batch reactor 31 Pd/TiO 2 , 18 Pt/Ga 2 O 3 , 32 Ga−Pt/TiO 2 −SiO 2 , 33 Au/ZnO, 17 Ag-HPW/TiO 2 , 34 Au@ZnO/TiO 2 , 19 Ga/ETS-10, 35 and AuPd/ ZnO. 36 significantly lower than what was previously reported (Figure S2).…”

“…(d) Benchmarking the performance in the production of C 2 H 6 by photocatalytic CH 4 coupling in batch reaction systems (see “Supplementary note 2” in the SI). Data used from references: Nb 2 O 5 , Pd/TiO 2 , Pt/Ga 2 O 3 , Ga–Pt/TiO 2 –SiO 2 , Au/ZnO, Ag-HPW/TiO 2 , Au@ZnO/TiO 2 , Ga/ETS-10, and AuPd/ZnO …”

In Situ Generation of H2O2 over MoOx Decorated on Cu2O@CuO Core–Shell Particle Nanoarchitectonics for Boosting Photocatalytic Oxidative Desulfurization

“…The high-resolution curves in the Cu 2p 3/2 region were deconvoluted into two peaks at 932.4 and 933.7 eV (Figure b and Table S2), corresponding to Cu­(I) and Cu­(II) species in Cu 2 O and CuO, respectively . In the oxygen species analysis, three peaks were identified at binding energies of 530.0, 531.4, and 533.0 eV (Figure c), attributed to lattice oxygen (O lat ), adsorbed oxygen species (O ad ), and adsorbed water, respectively . MoO x /Cu 2 O@CuO showed a higher O ad /O lat ratio compared to Cu 2 O@CuO, indicating an increase in oxygen vacancies that augment the O 2 activation capacity. , The catalyst displayed a Mo 3d doublet with binding energies of 231.1 and 234.2 eV (Figure d), suggesting a valence of Mo sites between Mo­(VI) and Mo­(IV).…”

Photo-Induced Active Lewis Acid–Base Pairs in a Metal–Organic Framework for H2 Activation

“…In total, an average of ca. 6 coordination 6.4 (7) for Ru/bpy and 5.8 (5) for Ru/NH 2 can be fitted. The degeneracy obtained from fitting for Ru/bpy shows a value of 2.0(2) Ru−N from the bipyridine linker, 2.2(3) Ru−O from adsorbed H 2 O and 2.2(2) Ru−Cl.…”

“…From the pioneering work of Welch and Stephan, who reported the heterolytic fission of the H–H bond by sterically bulky phosphines and boranes, the application of FLP in catalysis have been prominent in the activation of different small molecules including CO 2 and alkynes since the extension of the concept into heterogeneous systems by combining imines and nitriles as Lewis base and the gold surface as Lewis acid . Geometrically separated anion vacancies and hydroxyl groups have then been reported as Lewis basic and acidic sites, respectively. – However, the majority of such FLP catalysts have the Lewis basic and acidic sites separately introduced, which prohibits precise control of the location and quantity of the active sites. Further advancement in synthesis methods would be required for the improved catalytic application of FLP for small-molecule activation by enhanced control of the active sites.…”