Highly-Ordered Mesoporous Carbon Nitride with Ultrahigh Surface Area and Pore Volume as a Superior Dehydrogenation Catalyst

Abstract

In this work, a highly ordered mesoporous carbon nitride nanorods with 971–1124 m2 g–1 of superhigh specific surface area, 1.31–1.79 cm3 g–1 of ultralarge pore volume, bimodal mesostructure, and 9.3–23 wt % of high N content was prepared via a facile nanocasting approach using SBA-15 as template and hexamethylenetetramine as carbon nitride precursor, and the specific surface area and pore volume as well as N content are strongly dependent on the chosen precursor and pyrolysis temperature. The as-prepared materials were well characterized by HRTEM, FESEM, XRD, BET, Raman, FT-IR, XPS, and the textural structure and morphology were confirmed. The finding breaks through the bottleneck problems for fabricating mesoporous carbon nitride with both ultrahigh surface area and super large pore volume by employing an unexplored hexamethylenetetramine as carbon nitride precursor. The current synthetic strategy can be extended to the preparation of various mesoporous carbon nitride with different textural characteristics by using diverse templates under changeable preparation conditions. The developed mesoporous carbon nitride material with 750 °C of pyrolysis temperature exhibits high superior catalytic performance, ascribed to the promoting effect of nitrogen within the carbon matrix, the rich CO group and defect/edge feature on the surface, small size of graphitic crystallite, as well as the ultrahigh surface area and pore volume. It can also be concluded that the microstructures including bulk and surface structure features and surface chemical properties of the carbon-based materials have a decisive influence on their catalytic performance. The developed material can be employed in various organic transformations such as the base-catalyzed reactions, selective oxidation, dehydrogenation, photocatalysis, and electrocatalysis as well as acting as a novel and efficient candidate for CO2 capture, supercapacitor, purification of contaminated water, and future drug-delivery systems.

Activation of peroxymonosulfate by graphitic carbon nitride loaded on activated carbon for organic pollutants degradation

“…which showed typical flat layer structure in several micrometers, the size of the group [35], N-C-O group arised from oxidation of the precursors during the process [36], and adsorbed water [37], respectively. These electronegative N and O groups can be performed as active sites for PMS decomposition and pollutants degradation.…”

“…The C=O groups possess substantial electron density at the oxygen atom and can serve as a Lewis base to efficiently catalyze many reactions [35], through which the C=O is transformed to be hydroxyl group (C−OH) performing as an intermediate. The catalytic cycle is realized by the oxidation of C−OH to C=O.…”

“…4(A) shows strong signals from C, N and O elements. The spectrum of C 1s in the catalyst(Fig.4(B)) could be deconvoluted into four single peaks that correspond to C=C (284.6 eV), C−C or C-N (285.6 eV), C-O (286.5eV) and C=N or C=O (288.5 eV) functional groups[35]; while fitting of the N1s inFig. 4(C) envelope resulted in the identification of three chemical states of nitrogen at 398.8, 400 and 401 eV, corresponding to sp 2 hybridized aromatic N bonded to carbon atoms in the form of C=N-C, the tertiary N bonded to carbon atoms N-(C)3 and amino functions carrying hydrogen (C-N-H) related to structural defects, respectively[33].…”

Pore confinement effects and stabilization of carbon nitride oligomers in macroporous silica for photocatalytic hydrogen production

“…With respect to morphology, the specific photocatalytic activity of carbon nitrides has been improved by increasing the surface area via the introduction of mesopores, [22,[35][36][37][38][39][40][41] nanosheet exfoliation, [42][43][44] and synthesis of morphologies containing a range of nano-to macroscopic structural features. [39,[45][46][47][48][49][50][51][52][53] The specific activity of these morphologies is typically increased by 3-10 fold compared to the bulk carbon nitride under visible light (≥ 400 nm) illumination.…”

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“…Profiles of the generated XRD peaks of these samples were analyzed and matched up with the corresponding peaks using the JCPDS chemical spectra data bank. [27][28][29] From Figure 2, a sharp peak at two theta degree of approximately 26 can be observed for Cat-CNH and is representative of a graphite (002) framework. 19 The existence of two other graphitic broad peaks were also confirmed at two theta degrees of 42 (100) and 44 (101).…”