Promoted Electron Transfer and Surface Absorption by Single Nickel Atoms for Photocatalytic Cross-Coupling of Aromatic Alcohols and Aliphatic Amines under Visible Light

Abstract

The preparation of imines has drawn increasing attention as they are fundamental intermediates in the production of pharmaceuticals, agricultures, and fine chemicals. Nevertheless, current approaches for imines synthesis mainly focus on thermally driven reactions which always involve the consumption of high price noble metal catalysts, expensive ligands, strong base, and harsh reaction conditions. Herein, we demonstrate single atom nickel anchored on polymeric carbon nitride (Ni-SA@PCN) in Ni−N 4 structure for visible light-promoted crossed coupling between aromatic alcohols and aliphatic amines. As expected, the Ni atoms dispersed carbon nitride demonstrates an obviously improved charge separation and transfer as reflected in UV−vis, fluorescence intensity and lifetime, photocurrent density, and electrochemical impedance characterizations. More impressively, the density functional theory (DFT) calculations also reveals that the presence of Ni atoms can dramatically accelerate the absorption of reactive substrates on the surface of PCN. The decreased absorption energy from −0.51 to −3.35 eV, associated with increased OO bond length from 1.226 to 1.371 Å indicates a huge advantage of single Ni atom on oxygen activation. As a result, the obtained Ni-SA@PCN photocatalyst shows a prominent catalytic efficiency in imines formation with a reaction conversion of 73% and selectivity of >99%. Lastly, the photocatalytic reactions displays an excellent compatibility with various imines being achieved with high yield.

Enhanced Photocatalytic Efficiency in Visible-Light-Induced NADH Regeneration by Intramolecular Electron Transfer

“…While DTS@CMP-0 displays a maximum and onset absorption of 415 and 700 nm, respectively, an obvious bathochromic shift was found in the absorption of DTS@CMP-1 due to an enhanced conjugation degree caused by the introduction of dibenzothiophene sulfone. In addition, the absorption band of DTS/Rh@CMP-1 shows slight redshift, indicating the presence of metal-to-ligand charge transfer (MLCT) which is in good agreement with previous reports. , The optical band gaps of 2.05, 2.02, 2.14, and 1.87 eV were determined for DTS@CMP-1, DTS/Rh@CMP-1, DTS@CMP-0, and BT@CMP-6, respectively, based on the Kubelka–Munk function (Figure S13). It seems that the ratio of dibenzothiophene and bipyridine has an insignificant influence on the light absorption and optical band gap of polymers (Figure S14).…”

“…In addition, the absorption band of DTS/ Rh@CMP-1 shows slight redshift, indicating the presence of metal-to-ligand charge transfer (MLCT) which is in good agreement with previous reports. 41,42 The optical band gaps of 2.05, 2.02, 2.14, and 1.87 eV were determined for DTS@CMP-1, DTS/Rh@CMP-1, DTS@CMP-0, and BT@CMP-6, respectively, based on the Kubelka−Munk function (Figure S13). It seems that the ratio of dibenzothiophene and bipyridine has an insignificant influence on the light absorption and optical band gap of polymers (Figure S14).…”

Rational design, application and dynamic evolution of Cu–N–C single-atom catalysts

“…Microwave (MW) heating is considered an interesting method for the synthesis of inorganic nanomaterials because it not only greatly shortens the reaction time, but also inhibits the side reactions, thus signicantly improving the efficiency and yield of specic synthetic materials. [109][110][111] The heating process of the MW heating method is very rapid, which reduces the chance of metal agglomeration and helps to form isolated metal sites. Fei and coworkers prepared a series of SACs (M-NG-MW with M ¼ Cu, Ni, and Co) with N-doped graphene as a carrier by MW heating technology and conrmed the uniformly dispersed metal sites by X-ray adsorption ne structure analysis (XAFS) and scanning transmission electron microscopy (STEM) (Fig.…”

Elucidation of single atom catalysts for energy and sustainable chemical production: Synthesis, characterization and frontier science

“…• Carbon/Graphene [74,101,143,214,230,236,353] • Carbon nitride [101,[365][366][367] • CeO 2 [368] • Hydroxyapatite [369,370] • Ball milling [353] • Coordination site strategy [370] • Co-precipitation [368] • Electrochemical method [230] • CO 2 methanation [220] • CO 2 RR [74,101] • Cross-coupling [367] • Dry reforming [164,368,369,371] (continued on next page) reused more than six times TPD cycles with constant selectivity of butadiene to butene (~25%) as shown in Fig. 19(a) [257] In order to demonstrate the hydrogenation capability of the Pt-Cu SAC in different stressful conditions (with impurities), the authors tested the SAC in the presence of excess propylene and found that the propylene has no significant effect on the activity and selectivity of hydrogenation • TiO 2 [370] • Y 2 O 3 [220] • ZnO [361] • ZrO 2 [86] • Facile method [371] • Ion-exchange method [86] • Low temperature-induced strategy [220] • Mass-selected soft-landing [236] • Microwave-assisted method [367] • Pyrolysis-assisted method [101] • SEA [164,369] • Sol-gel method…”