No 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.