Jie Zhang,Weixiang Geng,Lei Shi,Chun Yang,Xiaoxin Zhang,Yi Geng,Rajan Arjan Kalyan Hirani,Xinyuan Xu,Juntao Wei,Yu Jing,Shu Zhang,Hong Zhang,Shaobin Wang,Hongqi Sun
The earth–abundant, highly active, and multifunctional catalysts have attracted enormous interest in heterogeneous catalysis for environmental remediation. Herein, boron and nitrogen co–doped porous nanocarbons (BNC) are synthesized with a one–pot and scalable approach as promising metal–free catalyst materials. The resulting BNC catalysts display controllable morphologies varying from the nanotubes to nanosheets, along with tunable C–N and B–C ratios. Possessing large surface area, highly accessible active centers as well as excellent adsorption capacity, the as–prepared BNC catalysts demonstrate an outstanding hydrogenation reduction of nitrophenols to corresponding aminophenols. Taking 4–nitrophenol reduction as proof–of–concept, the as–synthesized BNC–H-0.30 catalyst exhibits an impressive catalytic activity with a low activation energy of 30.65 kJ mol −1 , an impressive reaction rate constant of 6.99 × 10 −3 s −1 , and acceptable recyclability for 7 cycles without obvious activity decline. Combining both experimental exploration and density functional theory (DFT) calculation, the synergistic effect of graphite N and BCO 2 structures within the carbon framework mainly contributes to the high activity. This work not only sheds new light on the rational design of versatile carbon–based catalysts, but paves a new avenue for efficient pollutant conversion and elimination.
Chunyang Nie,Zhenhua Dai,Wenjie Liu,Xiaoguang Duan,Chengyin Wang,Bo Lai,Zhimin Ao,Shaobin Wang,Taicheng An
Carbon-catalyzed persulfate activation is a metal-free advanced oxidation process for abating aqueous organic micropollutants. Recently, the electron-transfer mechanism in the activation of peroxydisulfate (PDS) has attracted tremendous interest due to its unknown nonradical reaction pathways. The conventionally used atomic-scale descriptors of adsorption energy (Eads), O–O bond length (lO–O) and S–O bond length (lS–O) cannot accurately reflect the ability of the functionalities of PDS in its activation. In this work, a new descriptor, local electrophilicity index (ω), which represents the oxidative capacity of adsorbed S2O82−, was included to identify the intrinsic active sites in carbocatalysts via density functional theory calculations. To verify the reliability of the proposed criteria, the catalytic performances of a series of highly boronated and nitrogenated carbon nanotube/nanosheet composites (BCN-NT/NS) with tailored physicochemical properties were comparatively studied for activating PDS to degrade phenol. By integrating the computational and experimental results, the catalytic activity of BCN-NT/NS was determined to not only be related to the contents of heteroatom dopants (B and N), but also the positions of B and N in the co-doping configurations. This study offers reliable criteria for determining the intrinsic catalytic sites in carbocatalysts for the activation of PDS based on an electron-transfer mechanism, which assists the rational design of nanocarbons as advanced catalysts for metal-free oxidation and water remediation.
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