A Mechanochemical‐Assisted Synthesis of Boron, Nitrogen Co‐Doped Porous Carbons as Metal‐Free Catalysts

Abstract

Ag reen and convenient solid-state method assisted by mechanical energy is employed for the synthesis of boron (B) and nitrogen (N) co-doped porous carbons (B,N-Cs). Glutamic acid (Glu) and boric acid (H 3 BO 3 )a re used as the N-containing carbon precursor and boron source,r espectively.T his methodi se asy to performa nd proved to be efficient towardsc o-doping Ba nd Ni nto the carbonm atrix with high contentso fB(7 atom %) and N( 10 atom %). By adjusting the molar ratio of H 3 BO 3 to Glu, the surface chemical states of Ba nd Nc ould be readily modulated. When increasing H 3 BO 3 dosage, the pore size of B,N-Cs could be tuned ranging from micropores to mesopores with aB runauer-Emmett-Teller (BET) surface area up to 940 m 2 g À1 .F inally,t he B,N-Csw ere applied as metal-free catalysts for the cycloaddition of CO 2 to epoxides, whicho utperform the Ndoped carbon catalyst( NC-900) and the physically mixed catalysto fN C-900/B 4 C. The enhanced activity is attributed to the cooperative effect between Ba nd Ns ites. X-ray photoelectron spectroscopy( XPS) analysisr eveals that BN 3 in the B,N-Cs serves as ac riticala ctive site for the cooperative catalysis.

Recent advances in metal-free heteroatom-doped carbon heterogonous catalysts

“…In 2019, Lu and co-workers 260 synthesized a series of boron and nitrogen co-doped porous carbons (B,N-Cs) by combining with ball milling and pyrolysis ( Fig. 47 ).…”

Mechanochemical Synthesis of Porous Carbons and Their Applications in Catalysis

“…After carbonization and the removal of TiO 2 by chlorine treatment at 900 °C, the carbon product was obtained, possessing specific surface area of up to 1814 m 2 g À 1 and welldefined mesopore structure. [22] Reproduced from the reference [22] with permission from Wiley-VCH.…”

“…Our group reported a mechanochemical‐assisted method for preparing a series of B, N co‐doped porous carbons. In the bottom‐up synthesis strategy (Figure a), ball milling was employed to efficiently mix glutamic acid (Glu, N‐containing carbon source) with boric acid (H 3 BO 3 ). The mechanical action favored homogeneous dispersion of B and N dopants into the whole Glu/H 3 BO 3 composite possibly due to the hydrogen‐bond interaction, thus was conducive to the formation of B−N structure distributed uniformly in the carbon matrix.…”

“…(a) Synthesis procedure of the porous B, NÀ Cs assisted by mechanochemical method. (b) The possible mechanism of the cycloaddition of CO 2 to epoxides over the B, NÀ Cs/n-NBu 4 Br catalysts [22]. Reproduced from the reference[22] with permission from Wiley-VCH.…”