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Talapaneni, Siddulu Naidu,Kim, Jaehoon,Je, Sang Hyun,Buyukcakir, Onur,Oh, Jihun,Coskun, Ali The Royal Society of Chemistry 2017 Journal of materials chemistry. A, Materials for e Vol.5 No.24
<P>We report on the bottom-up synthesis of a fully sp<SUP>2</SUP>-hybridized nitrogenated three-dimensional microporous graphitic framework (3D-MGF) starting from a highly preorganized, saddle-shaped tetraphenylene derivative under ionothermal reaction conditions. The 3D-MGF showed high stability and a surface area of 928 m<SUP>2</SUP> g<SUP>−1</SUP> along with a narrow pore size distribution. Our approach enabled template-free inclusion of the third dimension into the graphitic frameworks while retaining π-conjugation and conductivity, which was verified by their activity as metal-free electrocatalysts for the hydrogen evolution reaction.</P>
Lee, Yoon Jeong,Talapaneni, Siddulu Naidu,Coskun, Ali American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.36
<P>Chemical activation of porous/nonporous materials to achieve high surface area sorbents with enhanced textural properties is a very promising strategy. The chemical activation using KOH, however, could lead to broad distribution of pores originating from the simultaneous pore deepening and widening pathways. Accordingly, establishing correlation between the chemical/textural properties of starting porous/nonporous materials and various pore formation mechanisms is quite critical to realize superior porosity and gas uptake properties. Here,, we show that the chemical and textural properties of starting porous organic polymers, that is, covalent triazine frameworks (CTF), have profound effect on the resulting porosity of the frameworks. The chemical activation of microporous CTF-1 using KOH at 700 degrees C enabled the preparation of chemically activated CTF-1, caCTF-1-700, which predominantly showed pore deepening, leading to an increased surface area of 2367 m(2) g(-1) and significantly enhanced gas adsorption properties with CO2 uptake capacities up to 6.0 mmol g(-1) at 1 bar and 1.45 mmol g(-1) at 0.15 bar and 273 K along with a isosteric heats of adsorption (Q(st)) of 30.6 kJ mol(-1). In addition, a remarkable H-2 uptake capacity of 2.46 and 1.66 wt % at 77 and 87 K, 1 bar along with the Q(st) value of 10.95 kJ mol-1 at zero coverage was also observed for the caCTF-1-700. Notably, the activation of mesoporous CTF-2 under the same conditions was accompanied by a decrease in its surface area and also in the conversion of mesopores into the micropores, thus leading to a pore deepening/narrowing rather than widening. We attributed this result to the presence of reactive weak spots, triazine moieties, for the chemical activation reaction within the CTF backbone. These results collectively suggest the critical role of chemical and pore characteristics of porous organic polymers in chemical activation to realize solid-sorbents for high capacity gas storage applications.</P>
Superior adsorption capacity of mesoporous carbon nitride with basic CN framework for phenol
Haque, Enamul,Jun, Jong Won,Talapaneni, Siddulu Naidu,Vinu, Ajayan,Jhung, Sung Hwa The Royal Society of Chemistry 2010 Journal of materials chemistry Vol.20 No.48
<p>Highly basic 2D-mesoporous carbon nitride (MCN-1) shows the highest adsorption capacity and adsorption kinetic constant for phenol due to its well ordered porous structure with the in-built basic NH and NH<SUB>2</SUB> groups on the surface, high surface area and large pore volume, suggesting the potential application of MCN-1 for the purification of contaminated water.</p> <P>Graphic Abstract</P><P>The highest adsorption capacity and kinetic constant for phenol adsorption has been achieved over mesoporous carbon nitride due to the presence of in-built basic functional groups and excellent textural parameters. <img src='http://pubs.rsc.org/ej/JM/2010/c0jm02974b/c0jm02974b-ga.gif'> </P>
Charged Covalent Triazine Frameworks for CO<sub>2</sub> Capture and Conversion
Buyukcakir, Onur,Je, Sang Hyun,Talapaneni, Siddulu Naidu,Kim, Daeok,Coskun, Ali American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.8
<P>The quest for the development of new porous materials addressing both CO2 capture from various sources and its conversion into useful products is a very active research area and also critical in order to develop a more sustainable and environmentally-friendly society. Here, we present the first charged covalent triazine framework (cCTF) prepared by simply heating nitrile functionalized dicationic viologen derivatives under ionothermal reaction conditions using ZnCl2 as both solvent and trimerization catalyst. It has been demonstrated that the surface area, pore volume/size of cCTFs can be simply controlled by varying the synthesis temperature and the ZnCl2, content. Specifically, increasing the reaction temperature led to controlled increase in the mesopore content and facilitated the formation of hierarchical porosity, which is critical to ensure efficient mass transport within porous materials. The resulting cCTFs showed high specific surface areas up to 1247 m(2) g(-1), and high physicochemical stability. The incorporation of ionic functional moieties to porous organic polymers improved substantially their CO2 affinity (up to 133 mg g(-1), at 1 bar and 273 K) and transformed them into hierarchically porous organocatalysts for CO2 conversion. More importantly, the ionic nature of cCTFs, homogeneous charge distribution together with hierarchical porosity offered a perfect platform for the catalytic conversion of CO2 into cyclic carbonates in the presence of epoxides through an atom economy reaction in high yields and exclusive product selectivity. These results clearly demonstrate the promising aspect of incorporation of charged units into the porous organic polymers for the development of highly efficient porous organocatalysts for CO2 capture and fixation.</P>
Adsorption of Phenol on Mesoporous Carbon CMK-3: Effect of Textural Properties
Haque, Enamul,Khan, Nazmul Abedin,Talapaneni, Siddulu Naidu,Vinu, Ajayan,JeGal, Jong-Geon,Jhung, Sung-Hwa Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.6
Mesoporous carbon CMK-3s with different textural properties have been used for the adsorption of phenol to understand the necessary physicochemical properties of carbon for the efficient removal of phenol from contaminated water. The kinetic constants (both pseudo-second order and pseudo-first-order kinetics) increase with increasing pore size of carbons. The maximum adsorption capacities correlate well with micropore volume compared with surface area or total pore volume even though large pore (meso or macropore) may contribute partly to the adsorption. The pore occupancies also explain the importance of micropore for the phenol adsorption. For efficient removal of phenol, carbon adsorbents should have large micropore volume and wide pore size for high uptake and rapid adsorption, respectively.
Adsorption of Phenol on Mesoporous Carbon CMK-3: Effect of Textural Properties
Enamul Haque,Nazmul Abedin Khan,Siddulu Naidu Talapaneni,Ajayan Vinu,제갈종건,정성화 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.6
Mesoporous carbon CMK-3s with different textural properties have been used for the adsorption of phenol to understand the necessary physicochemical properties of carbon for the efficient removal of phenol from contaminated water. The kinetic constants (both pseudo-second order and pseudo-first-order kinetics) increase with increasing pore size of carbons. The maximum adsorption capacities correlate well with micropore volume compared with surface area or total pore volume even though large pore (meso or macropore) may contribute partly to the adsorption. The pore occupancies also explain the importance of micropore for the phenol adsorption. For efficient removal of phenol,carbon adsorbents should have large micropore volume and wide pore size for high uptake and rapid adsorption,respectively.
Joseph, Stalin,Kempaiah, Devaraju M.,Benzigar, Mercy,Baskar, Arun V.,Talapaneni, Siddulu N.,Jhung, Sung Hwa,Park, Dae-Hwan,Vinu, Ajayan The Royal Society of Chemistry 2017 Journal of Materials Chemistry A Vol.5 No.40
<P>In this work, we report a simple and versatile method for the preparation of mesoporous carbon nitrides (MCNs) functionalized with highly dispersed chromium oxide nanoparticles by using a metal organic framework, MIL-100(Cr), as a template and aminoguanidine hydrochloride (AG) as a high nitrogen content single molecular precursor. We are able to synthesise these metal oxide functionalized MCN materials with single step carbonization but without using any toxic template removal process using HF or NaOH. The absence of a washing procedure with toxic acid also allows the incorporation of a large amount of metal oxide particles inside the porous channels of MCNs. The obtained MCN materials exhibit a high specific surface area and a large pore volume. The AG to template ratios are varied to control the amine functional groups and the textural parameters including the specific surface area and pore volume. It is found that the AG to template ratio of 1.5 is the best condition to obtain MCNs with a specific surface area of 1294 m<SUP>2</SUP> g<SUP>−1</SUP>, which is the highest value reported so far for MCN-based materials. FT-IR and XPS results reveal that the prepared materials contain free NH2 groups within the CN network which help to anchor metal oxide nanoparticles and provide highly dispersed basic sites. These functionalized MCN materials are also used as adsorbents for CO2 capture. Among the materials studied, the MCN with the highest specific surface area shows the largest CO2 adsorption capacity (16.8 mmol g<SUP>−1</SUP>) which is much higher than those of MCN materials prepared from SBA-15 and KIT-6, activated carbon, MIL-100(Cr), SBA-15, and multiwalled carbon nanotubes. This high adsorption capacity is mainly due to the strong synergistic effect between the MCN with high specific surface area and highly dispersed metal oxide nanoparticles.</P>
Buyukcakir, Onur,Je, Sang Hyun,Choi, Dong Shin,Talapaneni, Siddulu Naiudu,Seo, Yongbeom,Jung, Yousung,Polychronopoulou, Kyriaki,Coskun, Ali The Royal Society of Chemistry 2016 Chemical communications Vol.52 No.5
<P>Porous cationic polymers (PCPs) with surface areas up to 755 m(2) g(-1) bearing positively charged viologen units in their backbones and different counteranions have been prepared. We have demonstrated that by simply varying counteranions both gas sorption and catalytic properties of PCPs can be tuned for metal-free capture and conversion of CO2 into value-added products such as cyclic carbonates with excellent yields.</P>