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 CO 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.
Direct selective oxidation of hydrocarbons to oxygenates by O2 is challenging. Catalysts are limited by the low activity and narrow application scope, and the main focus is on active C−H bonds at benzylic positions. In this work, stable, lead‐free, Cs3Bi2Br9 halide perovskites are integrated within the pore channels of mesoporous SBA‐15 silica and demonstrate their photocatalytic potentials for C−H bond activation. The composite photocatalysts can effectively oxidize hydrocarbons (C5 to C16 including aromatic and aliphatic alkanes) with a conversion rate up to 32900 μmol gcat−1 h−1 and excellent selectivity (>99 %) towards aldehydes and ketones under visible‐light irradiation. Isotopic labeling, in situ spectroscopic studies, and DFT calculations reveal that well‐dispersed small perovskite nanoparticles (2–5 nm) possess enhanced electron–hole separation and a close contact with hydrocarbons that facilitates C(sp3)−H bond activation by photoinduced charges.
Solar-driven photocatalysis has attracted significant attention in water splitting, CO2 reduction and organic synthesis. The syntheses of valuable azo- and azoxyaromatic dyes via selective photoreduction of nitroaromatic compounds have been realised using supported plasmonic metal nanoparticles at elevated temperatures (≥90 °C); however, the high cost, low efficiency and poor selectivity of such catalyst systems at room temperature limit their application. Here we demonstrate that the inexpensive graphitic C3N4 is an efficient photocatalyst for selective syntheses of a series of azo- and azoxy-aromatic compounds from their corresponding nitroaromatics under either purple (410 nm) or blue light (450 nm) excitation. The high efficiency and high selectivity towards azo- and azoxy-aromatic compounds can be attributed to the weakly bound photogenerated surface adsorbed H-atoms and a favourable N-N coupling reaction. The results reveal financial and environmental potential of photocatalysis for mass production of valuable chemicals.
A nanodiamond/CNx hybrid fabricated through a facile pyrolysis approach exhibits superior catalysis that is dependent on the structure and surface chemical properties.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.