Nanomaterials
·
2019
·Vol. 9
·期 9
·1321
·
IF 4.034
Jinrong Lu,Zihan Li,Weijia An,Li Liu,Wenquan Cui
Metal-free porphyrin with good planarity is beneficial to π–π stack interactions, which promotes electron coupling and the separation and transfer of photogenerated carriers. It is necessary to develop metal-free porphyrin-based photocatalysts and exploit the photocatalytic mechanism. Herein, metal–free porphyrin (5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin, TCPP) was self-assembled through an acid-based neutralization reaction and mixing dual-solvents under surfactants to form different aggregates. Morphology structures, optical and optoelectronic properties of the TCPP aggregates were characterized in detail. TCPP self-assemblies showed higher photocatalytic activities for the degradation of phenol under visible light than untreated TCPP powders, and the aggregates of nanorods formed through the acid-based neutralization reaction in the presence of hexadecyl trimethyl ammonium bromide (CTAB) possessed 2.6 times more activity than the nanofiber aggregates formed through mixing dual-solvents. It was proved that self-assembly methods are crucial for controlling the aggregation of porphyrins to form different aggregations, which have a profound impact on the photocatalytic activity.Keywords:metal-free porphyrin;self-assembly;aggregation mode;photocatalysis
研究领域:
化学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CARBON
·
2015
·
IF 6.196
Yunfeng Zhan,Jilin Huang,Zhipeng Lin,Xiang Yu,Dongrong Zeng,Xiaoxue Zhang,Fangyan Xie,Weihong Zhang,Jian Chen,Hui Meng
By doping graphene with iodine and ammonia, I and N co-doped graphene (ING) is prepared and used as metal free catalyst for the oxygen reduction reaction (ORR) both in alkaline and acidic media. The as-prepared catalyst exhibits striking activity in alkaline with an onset potential of 0.945 V (vs. RHE) which is the same with commercial Pt/C catalyst. In acidic media the ING shows a competitive activity. In both alkaline and acidic media the ORR is four-electron process catalyzed by ING. The superior ORR performance of the ING can be attributed to the synergetic doping effect of I and N. Based on its outstanding performance the ING can work as a metal free catalyst for fuel cell with much lower cost than currently used Pt/C catalyst.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2020
·
IF 6.182
Jianmei Pan,Wei Shen,Yahai Zhang,Hua Tang,Haoyu Sun,Wenqiang Zhong,Xuehua Yan
Photocatalytic water splitting to product hydrogen (H 2 ) is a desired route to utilize solar energy into chemical energy. At present, most photocatalysts for H 2 generation contains metallic elements with high-cost, confined reserves, and environmentally unfriendly. The exploitation of metal-free and efficient photocatalysts becomes particularly important. Herein, a new metal-free g-C 3 N 4 -based heterojunction composites were facilely produced via the ultrasonic assisted deposition and subsequent calcination from g-C 3 N 4 layers embedded with SiOC with prominent conductivity and large surface area. Systematic investigates suggested that the SiOC/g-C 3 N 4 heterojunctions exhibited eminently meliorated photocatalytic H 2 production efficiency. The optimum H 2 production rate (1020 μmol h −1 g −1 ) of the SiOC/g-C 3 N 4 photocatalyst is 3.2 and 25.5 folds that of g-C 3 N 4 and SiOC , respectively. The boosted photocatalytic activity primarily originates from the increased absorptivity of light, the markedly expedited charge migration and the impeded recombination of charge carriers. This study offers a new perspective for the scientific contrive and fabrication of high-quality heterojunction photocatalysts for solar energy utilization.
研究领域:
材料科学
·
能源科学
✓ 已验证
DOI
高影响因子
ACS Omega
·
2022
·
IF 4.132
Moaz M. Abdou,Paul M. O’Neill,Eric Amigues,Magdalini Matziari
A novel TEA-catalyzed sugar-esterification of phosphinic acids was used as a general and efficient approach for the synthesis of a variety of phosphinates without any transition metal. The high efficiency of the current methodology and a convenient experimental procedure compensate for the moderate yields obtained. Another advantage is that the reaction tolerates different substituents attached to the phosphinic acids and the sugar moieties alongside the ease of isolation of the product.
研究领域:
有机化学
·
合成化学
✓ 已验证
DOI
PubMed
高影响因子
EUROPEAN POLYMER JOURNAL
·
2024
·
IF 5.8
Shufang Wu,Yushu Zhang,Zhiquan Li,Xiaoxuan Liu,Yusuf Yagci
A metal-free approach to visible-light LED-induced atom transfer radical polymerization (ATRP) using oligopyrene as a photocatalyst is reported. The method facilitates the polymerization of various vinyl monomers, yielding polymers with molecular weight distribution as low as 1.32 and controlled chain-end functionality. Light on/off experiments demonstrate the light-dependent nature of the polymerization, confirming the effectiveness of the oligopyrene/alkyl halide system. The presented strategy paves the way for future advancements in polymer science, offering a metal-free alternative for controlled polymerization under visible light irradiation.
研究领域:
高分子化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF SOLID STATE CHEMISTRY
·
2021
·
IF 3.498
Feiyi Lyu,Zhuo Chen,Ruowen Shi,Jiase Yu,Bo-Lin Lin
Metal-free perovskites , a new class of perovskite materials, show attractive piezoelectric , ferroelectric and pyroelectric properties because of their intrinsic structural properties. The introduction of organic components also leads to desirable properties such as structural adjustability, high mechanical flexibility, environmentally friendly processing conditions and low treatment temperatures. However, explorations of new metal-free perovskite materials suffer from the drawbacks of their previous liquid phase synthesis method, such as high time cost and poor experimental reproducibility. Here, we reported the first solid-phase synthesis of metal-free perovskite crystalline materials. Using the optimized ball milling method, we found that the starting materials were fully converted to pure metal-free perovskite DABCO-NH 4 Br 3 (DABCO = N,N′-diazabicyclo [2.2.2] octonium) in the size of 5–10 μm. This solid phase synthesis strategy was successfully applied to the synthesis of MDABCO-NH 4 I 3 (MDABCO = N-methyl-N′-diazabicyclo [2.2.2] octonium), demonstrating the great potential for the preparation and exploration of metal-free perovskite materials via solid phase synthesis.
研究领域:
材料科学
·
化学
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry A
·
2020
·Vol. 8
·期 23
·11773-11780
·
IF 11.301
Qingyao Wu,Yan Liu,Jingjing Cao,Yue Sun,Fan Liao,Yang Liu,Hui Huang,Mingwang Shao,Zhenhui Kang
Photocatalytic water splitting to produce hydrogen and hydrogen peroxide is the main goal of photocatalysis. However, the reactions of both are water based and thus, it is extremely challenging to conduct both processes on one catalyst. Herein, a function-switchable metal-free catalyst was designed and synthesized through the polycondensation of procyanidin and 4-methoxybenzaldehyde. Impressively, the catalyst developed here not only split water to produce hydrogen via a four-electron reaction process in the absence of air, but also generated hydrogen peroxide by preferentially reducing oxygen via a two-electron pathway in air. The production rates of hydrogen and hydrogen peroxide reached 252.02 and 1385.42 μmol h−1 g−1, respectively. Through in situ transient photovoltage tests and kinetic analysis, a clear and fundamental understanding of the highly efficient and switchable functions was acquired for this photocatalyst. This study highlights the unique behavior and provides an insight into the design of function-switchable catalysts and the regulation of catalytic reactions.
研究领域:
材料科学
·
化学
✓ 已验证
DOI
高影响因子
NANO
·
2017
·
IF 1.025
Liming Chen,Lulu Zhao,Jie Xu,Jinlin Long,Linxi Hou
Metal-free photocatalysts trithiocyanuric acid (C 3 N 3 S 3 ) and its polymers were one-step synthesized and used for selective aerobic oxidation of benzyl alcohol under visible light. The S–S bridged C 3 N 3 S 3 polymers showed higher oxidation activity with increasing polymerization time and reached a maximum at 40 h. As a major factor, catalysts’ solubility in water at different temperatures (from 298.15 K to 368.15 K) was measured at atmospheric pressure. The obtained data were correlated by polynomial empirical equation and modified Apelblat equation, respectively. Experimental results proved that the solubility of C 3 N 3 S 3 and its polymers increased with increasing temperature. The solubility of C 3 N 3 S 3 polymers with lower polymerization degree (DP) were better than that of parent C 3 N 3 S 3 owing to the hydrophilicity caused by a low symmetry and disorder structure, whereas the higher DP could lead to the decrease of polymer solubility and further affect the photocatalytic activity. Thermodynamic properties of the solution system including the enthalpy ( Δ H S 0 ) and heat capacity ( c p 0 ) were calculated by the modified Apelblat equation.
研究领域:
化学
·
材料科学
✓ 已验证
DOI
高影响因子
Green Energy & Environment
·
2020
·
IF 6.395
Chen Xing,Daihui Yang,Yan Zhang,Tian Sun,Junfei Duan,Hussein A. Younus,Shiguo Zhang
Heteroatom-doped meso/micro-porous carbon materials are conventionally produced by harsh carbonization under an inert atmosphere involving specific precursors, hard/soft templates, and heteroatom-containing agents. Herein, we report a facile synthesis of N and O co-doped meso/micro-porous carbon (NOMC) by template-free carbonization of a small-molecule precursor in a semi-closed system. The semi-closed carbonizaiton process yields hydrophilic NOMCs with large surface area in a high yield. The porous structure as well as the elemental composition of NOMCs can be modulated by changing the holding time at a particular temperature. NOMCs as metal-free heterogeneous catalysts can selectively oxidize benzyl alcohol and its derivatives into aldehydes/ketones with > 85% conversion in aqueous solution, which is much higher than that of the control sample obtained in tube furnace (21% conversion), mainly due to their high N content, high percentage of pyridinic N, and large surface area. The presence of O-containing moieties also helps to improve the hydrophilicity and dispersion ability of catalysts and thus facilitates the mass transfer process during aqueous oxidation. The NOMC catalysts also dispayed excellent activity for a wide range of substrates with a selectivity of > 99%.
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
GREEN CHEMISTRY
·
2019
·Vol. 21
·期 15
·4169-4177
·
IF 9.405
Yang Peng,Xianghua Li,Tian Gao,Teng Li,Weiran Yang
Starch is available in large quantities and at cheap price, especially that from stale rice, root and tuber crops, etc., which makes it desirable for conversion to value-added products. A metal-free approach to convert starch to 5-methylfurfural (5-MF) using hydrochloric acid, sodium iodide and hydrogen in a biphasic solvent system has been developed. 5-MF is an important fine chemical, widely used in food, medicine, pesticides, cosmetics and other industries, and is also considered to be an important bio-gasoline precursor. I− has superior nucleophilic substitution properties and high reactivity towards C–O bond cleavage, which is crucial for this transformation. Under optimal reaction conditions, 38.0% of 5-MF and 45.6% of total organic products can be obtained from starch with 22.5% levulinic acid as the main side product. Besides, 80.8% 5-MF can be directly obtained from 5-hydroxymethylfurfural (HMF) through the same process. To the best of our knowledge, this is the first reported example of a metal-free process to convert starch and HMF directly to 5-MF. The reaction mechanism was well studied. The catalyst system was proved to be stable and was recycled five times without loss of activity.
研究领域:
化学工程
·
生物质转化
·
绿色化学
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Baogang Fu,Nan Su,Yun Wang,Xiangtong Zhou,Yidong Hu,Hongjun Dong,Chunmei Li
In order to achieve the sustainable production of hydrogen fuel, the heterogeneous photocatalysts with inimitable structure are always desired for the high-efficiency and stable H 2 production reaction from water splitting owing to the perfect structure–activity relationship. In this study, a novel metal-free one-dimensional/two-dimensional (1D/2D) heterojunction is constructed by a series of dissolution and diffusion, recrystallization and in-situ growth, and self-assembly process of 1-pyrene carboxaldehyde (PCHO) nanoribbons on the surface of polymeric carbon nitride (PCN) nanosheets. The obtained 1D/2D heterojunction can realize fast carrier transport along 1D nanoribbons to prevent the recombination of photogenerated carriers at the interface. Furthermore, the intrinsic Z-scheme reaction mechanism within the heterostructure also effectively inhibits electron-hole recombination and isolates the reduction and oxidation sites of the photocatalytic reaction. As a result, the dramatically enhanced photocatalytic hydrogen evolution (PHE) activity is achieved over the 1%-PCHO/PCN sample, the optimal PHE rate of which is approximately 5.4 times that of pure PCN . This work provides the deep insight into the design and exploitation of metal-free heterojunction with unique structure applied in the photocatalytic energy conversion field.
研究领域:
材料科学
·
能源化学
✓ 已验证
产品关联
DOI
高影响因子
International Journal of Electrochemical Science
·
2023
·
IF 1.5
Chang Liu,Shang Li,Yijing Xing,Huan Kang,Jinting Tan,Wei Guo,Mu Pan
Polyaniline (PANI) nanofibers were synthesized on carbon paper by electrochemical method, then heat-treated at temperatures of 800°C, 900°C, 1000°C and 1100°C to obtain a gas diffusion electrode (GDE). Fourier Transform infrared spectroscopy (FTIR), Scanning electron microscope (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the catalysts. The metal-free C-N catalyst with a reticular structure was coated on carbon paper. The ORR (oxygen reduction reaction) activity of metal-free C-N catalysts was evaluated by cyclic voltammetry (CV) and rotating disk electrode (RDE) in HClO 4 . The results showed that the catalysts heat-treated at 1000°C had the best ORR activity and better stability compared with the commercial Pt-based catalysts in acidic medium. The result of XPS showed that the activity of metal-free C-N catalysts was related to the pyridinic-type nitrogen. Finally, the advantages and disadvantages of these catalysts were discussed for further investigation.
研究领域:
材料科学
·
电化学
·
能源技术
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）