Despite being one of the oldest materials described in the chemical literature, graphitic carbon nitride (g-C3N4) has just recently experienced a renaissance as a highly active photocatalyst, and the metal-free polymer was shown to be able to generate hydrogen under visible light. The semiconductor nature of g-C3N4 has triggered tremendous endeavors on its structural manipulation for enhanced photo(electro)chemical performance, aiming at an affordable clean energy future. While pursuing the stem of g-C3N4 related catalysis (photocatalysis, electrocatalysis and photoelectrocatalysis), a number of emerging intrinsic properties of g-C3N4 are certainly interesting, but less well covered, and we believe that these novel applications outside of conventional catalysis can be favorably exploited as well. Thanks to the general efforts devoted to the exploration and enrichment of g-C3N4 based chemistry, the boundaries of this area have been possibly pushed far beyond what people could imagine in the beginning. This review strives to cover the achievements of g-C3N4 related materials in these unconventional application fields for depicting the broader future of these metal-free and fully stable semiconductors. This review starts with the general protocols to engineer g-C3N4 micro/nanostructures for practical use, and then discusses the newly disclosed applications in sensing, bioimaging, novel solar energy exploitation including photocatalytic coenzyme regeneration, templating, and carbon nitride based devices. Finally, we attempt an outlook on possible further developments in g-C3N4 based research.
Lithium-sulfur battery represents a promising class of energy storage technology owing to its high theoretical energy density and low cost. However, the insulating nature, shuttling of soluble polysulfides and volumetric expansion of sulfur electrodes seriously give rise to the rapid capacity fading and low utilization. In this work, these issues are significantly alleviated by both physically and chemically restricting sulfur species in fluorinated porous triazine-based frameworks (FCTF-S). One-step trimerization of perfluorinated aromatic nitrile monomers with elemental sulfur allows the simultaneous formation of fluorinated triazine-based frameworks, covalent attachment of sulfur and its homogeneous distribution within the pores. The incorporation of electronegative fluorine in frameworks provides a strong anchoring effect to suppress the dissolution and accelerate the conversion of polysulfides. Together with covalent chemical binding and physical nanopore-confinement effects, the FCTF-S demonstrates superior electrochemical performances, as compared to those of the sulfur-rich covalent triazine-based framework without fluorine (CTF-S) and porous carbon delivering only physical confinement. Our approach demonstrates the potential of regulating lithium-sulfur battery performances at a molecular scale promoted by the porous organic polymers with a flexible design.
A detailed magnetostratigraphic investigation, coupled with rock-magnetic studies, was carried out on a lacustrine sequence in the eastern Nihewan Basin, Northern China, which contains the Donggutuo and Maliang Paleolithic sites. Magnetite and hematite were identified as the main carriers for the characteristic remanent magnetizations. Magnetostratigraphic results show that the lacustrine sequence recorded the late Matuyama and Brunhes chrons. Furthermore, the Maliang artifact layer occurs just below the Brunhes/Matuyama boundary, and the Donggutuo artifact layer is just below the Jaramillo onset. Therefore, the age of the Maliang and Donggutuo artifact layers can be definitely estimated to be about 0.78 myr and 1.1 myr, respectively. These two paleomagnetic ages, coupled with previously obtained paleomagnetic data of the Majuangou, Xiaochangliang, Banshan, Lantian, and Xihoudu Paleolithic sites, suggest an expansion and lengthy flourishing of human groups from northern to north-central China during the entire Early Pleistocene.
Canned heat: Inhibition of anisotropic crystal growth is critical for synthesizing semiconductor/metal spheres, but it is kinetically difficult to achieve in methods relying on conventional heating. Selective heating of colloidal nanoparticles by pulsed laser irradiation allows size‐tailored semiconductor and metal submicrometer spheres to be synthesized.
Solar steam generation has been extensively studied for its potential application in power generation and water treatment. Although some efficient evaporators have been developed, the challenge of the abrupt drop in the evaporator performance under outdoor environments remains to be overcome. The heteroblasty of Monstera and other climbers allows them to grow rapidly under the extreme shade of a tropical rainforest, inspiring the design of a high-efficiency evaporator that can function even in weak light environments. Herein, artificial trees that imitate the leaf fenestration of Monstera combined with the Chinese paper cutting technique exhibit the highest evaporation rate of 2.30 kg m −2 h −1. Moreover, under oblique incidence (from 0° to 75°) and dappled sunlight, the evaporation rates of artificial trees with leaf fenestration are 1.08-1.26 and 1.34-2.78 times those of artificial trees without leaf fenestration and a 2D evaporator, respectively. The excellent performance is attributed to high-efficiency light absorption, photothermal conversion, high evaporation area, and excellent light and thermal management abilities, which are achieved through leaf fenestration and efficient thermal recovery through multiple reflections of light and thermal radiation between the leaves. The design of the 3D hierarchical structure and leaf fenestration are also applicable for various light absorbents.
Guo, Z. (2015). Large-scale synthesis of ordered mesoporous carbon fiber and its application as cathode material for lithium-sulfur batteries. Carbon, 81 782-787.Large-scale synthesis of ordered mesoporous carbon fiber and its application as cathode material for lithium-sulfur batteries
AbstractA novel type of one-dimensional ordered mesoporous carbon fiber has been prepared via the electrospinning technique by using resol as the carbon source and triblock copolymer Pluronic F127 as the template. Sulfur is then encapsulated in this ordered mesoporous carbon fibers by a simple thermal treatment. The interwoven fibrous nanostructure has favorably mechanical stability and can provide an effective conductive network for sulfur and polysulfides during cycling. The ordered mesopores can also restrain the diffusion of long-chain polysulfides. The resulting ordered mesoporous carbon fiber sulfur (OMCF-S) composite with 63% S exhibits high reversible capacity, good capacity retention and enhanced rate capacity when used as cathode in rechargeable lithium-sulfur batteries. The resulting OMCF-S electrode maintains a stable discharge capacity of 690 mAh/g at 0.3 C, even after 300 cycles.
ABSTRACT:A novel type of one-dimensional ordered mesoporous carbon fiber has been prepared via the electrospinning technique by using resol as the carbon source and triblock copolymer Pluronic F127 as the template. Sulfur is then encapsulated in this ordered mesoporous carbon fibers by a simple thermal treatment. The interwoven fibrous nanostructure has favorably mechanical stability and can provide an effective conductive network for sulfur and polysulfides during cycling. The ordered mesopores can also restrain the diffusion of long-chain polysulfides. The resulting ordered mesoporous carbon fiber sulfur (OMCF-S) composite with 63% S exhibits high reversible capacity, good capacity retention and enhanced rate capacity when used as cathode in rechargeable lithium-sulfur batteries. The resulting OMCF-S electrode maintains a stable discharge capacity of 690 mAh/g at 0.3 C, even after 300 cycles.
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