ACS Catalysis
·
2024
·
IF 11.3
Zhongyao Zhang,Feiting Zhang,Zhongxin Song,Lei Zhang
Metal-free carbon materials functionalized with pyridinic nitrogen groups exhibit promising electrocatalytic activity for the oxygen reduction reaction (ORR). However, not all pyridinic nitrogen groups are equally active for the ORR, which remains ambiguous and requires rigorous quantification and differentiation by their basicity. Here, we introduce the potentiometric titration method for identifying and quantifying nitrogen-containing groups on carbon materials by their Lewis basicity and reactivity in characteristic tests. Various carbon materials are functionalized with nitrogen heteroatoms. Potentiometric titration, X-ray photoelectron spectroscopy (XPS), and elemental analysis suggest that a significant amount of pyridinic nitrogen groups are buried within the bulk structures and cannot be accessed by protons and oxygen molecules. Besides, pyridinic nitrogen functions located adjacent to other nitrogen atoms exhibit weaker basicity due to strong inductive or resonance effects, resulting in a negligible contribution to the ORR activity. ORR measurements under alkaline conditions suggest that the titratable pyridinic nitrogen groups are essential for the active site (or site pair), and kinetic current density is directly proportional to the density of titratable pyridinic nitrogen groups. Furthermore, the turnover frequency for the ORR increases with the Lewis basicity of the pyridinic nitrogen groups for all investigated carbon materials in alkaline and acidic conditions. Density functional theory (DFT) calculations suggest that the ORR occurs on the carbon atoms adjacent to pyridinic nitrogen groups. Pyridinic nitrogen with a higher Lewis basicity can affect adjacent carbon atoms more efficiently, which stabilizes the key intermediates for the ORR and decreases the activation barrier. This work provides an informative and convenient way for characterizing nitrogen-containing groups on carbon materials, especially in quantifying the active pyridinic nitrogen sites for the ORR.
研究领域:
电化学
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催化科学
·
材料科学
✓ 已验证
DOI
高影响因子
SOLID STATE IONICS
·
2022
·
IF 3.699
Haisheng Yi,Yu Liu,Xia Lu
Interfacial chemistry plays an important role in understanding electrode process kinetics of many chemical reactions, e.g. photocatalyst , electrocatalyst , and electrochemistry . In this context, a systematic investigation is conducted to reveal the mechanism of electrode-electrolyte interface between Li 4 Ti 5 O 12 (LTO) spinel and electrolyte molecule, aiming to tackle the notorious package swelling issue in rechargeable batteries. Using the gas chromatography–mass spectrometry and electron microscopy techniques, the interplays between the LTO and dimethyl carbonate (DMC) are uncovered to be a synergetic chemical catalytic process involving the truncated oxygens of the surface Ti O dangling bonds , which are negatively polarized as the catalytic centers with the strong Lewis basicity . The Lewis basic centers catalyze the nucleophilic substitution of DMC with only trace amounts of water, resulting in the gaseous products, such as CO 2 and methanol. These findings deepen the understandings on the fundamental chemistry and catalysis of solid-liquid interfaces, especially the metal oxide-organic interfaces.
研究领域:
电化学
·
催化化学
✓ 已验证
DOI
高影响因子
WOOD SCIENCE AND TECHNOLOGY
·
2013
·Vol. 48
·期 1
·195-206
·
IF 1.884
Wang Ting,Si Hongyan,Li Bin
Poplar wood flour, a low-cost and abundantly available material, was modified by grafting β - cyclodextrin in the presence of citric acid, aiming to expand the application of wood flour. The product was characterized by Fourier transform infrared spectroscopy and the technique of the phenolphthalein probe. By the technique of inverse gas chromatography and the method of Hamieh, the values of surface free energy and nonpolar part of the free energy were obtained. The results demonstrate that the dispersive component of the surface free energy of the products will increase with temperature increases, and the product presents a Lewis basic character with K
b / K
a = 3.67. Based on the structure of the product, the basicity comes from two parts. One is the rich electronic environment of the β - CD inner cavity, and the other is the formation of ester bonds through crosslinking between β - CD and wood flour by CA.
研究领域:
高分子化学
·
木材科学
·
表面科学
·
材料化学
·
分析化学
✓ 已验证
DOI
高影响因子
Journal of Energy Chemistry
·
2020
·
IF 7.216
Jin Xie,Ziren Zhou,Hongwei Qiao,Mengjiong Chen,Lijie Wang,Shuang Yang,Yu Hou,Huagui Yang
A controllable crystallization is of practical importance to produce high-quality perovskite thin films with reduced structural defects. Lewis bases as electron-pair donor chemicals can strongly coordinate to lead ions and have been extensively employed to manipulate the growth of perovskite crystals. In this work, we demonstrate a series of Lewis-base amides, for morphological regulation of methylammonium lead triiodide (MAPbI 3 ) thin films. The screened acetamide was demonstrated to decently improve the grain size, along with a spatial distribution at grain boundaries (GBs). The mesostructured solar cells of acetamide-modified absorbers yielded an optimized power conversion efficiency (PCE) of 20.04% with a mitigated open-circuit voltage ( V OC ) deficit of 0.39 V. This work provides a facile and cost-effective strategy toward controllable fabrication of high-performance MAPbI 3 solar cells.
研究领域:
材料科学
·
能源技术
✓ 已验证
DOI
高影响因子
Journal of Energy Storage
·
2024
·
IF 8.9
Xueting Yang,Haoyu Deng,Jie Xu,Dezhan Ye,Xiancai Jiang,Yazhou Chen,Ke Sun,Zengjin Liu
1,3-dioxolane (DOL) shows low interfacial impedance and high Coulombic efficiency, thus its polymer electrolytes have attracted extensive attention. In order to initiate DOL polymerization, catalyst amount of LiPF 6 is usually used rather than as the main lithium salt . Totally replacement of LiTFSI with low cost of LiPF 6 could bring the heat explosion and high viscosity when mixing DOL with 0.9 M LiPF 6 electrolyte (carbonate ester solvent). Here, based on the Lewis acid-base interaction, a new type of Lewis base, pyridine, is added to control the explosive polymerization of 1,3-dioxolane in LiPF 6 electrolyte. Through tuning the pyridine content, the gelling process and electrochemical properties could be controlled. It is demonstrated that the optimized monomer conversion and electrochemical window are up to 85.2 % and 4.6 V; meanwhile, the optimized conductivity and transfer number are 0.99 × 10 −3 S/cm (25 °C) and 0.68, respectively. The stable interface between PDOL and lithium metal anode could be proved by the stable over-potential (50mv, 700 h) at current density of 0.5 mA cm −2 . After 500 cycles at 2C, the assembled Li/PDOL@py 0.125 /LiFePO 4 battery delivers 115 mAh/g and 90 % capacity retention, with high average Coulombic efficiency of 99.83 %. The present results demonstrate the heat suppression role of pyridine toward mixing DOL with 0.9 M LiPF 6 electrolyte, which solves the heat and viscosity problems for PDOL based gelling polymer electrolytes .
研究领域:
电化学
·
高分子化学
·
能源材料
·
锂离子电池
·
界面化学
·
功能材料
✓ 已验证
DOI
高影响因子
SYNTHETIC METALS
·
2023
·
IF 4.4
Shuai Fu,Yuhui Ma,Zhiyuan Zhang,Yao Xu,Heyi Zhang,Zihan Xiao,Sihao Zhang,Ruidong Xia
A high-quality perovskite film is of great significance for efficient and stable perovskite solar cells (PSCs). The use of additives to improve the crystallinity and morphology of perovskite films is an effective way to improve the performance of PSC devices. In this work, 4-carboxyphenyl isothiocyanate (CPIC) was used as an additive in perovskite films to improve the quality of the films. The results of FT-IR showed that the SCN - and -COOH groups with Lewis base in CPIC can coordinate with unpaired Pb 2+ on the perovskite films to form Lewis acid-base adducts. The addition of CPIC can effectively improve the crystallinity and grain size of the perovskite films. The results showed that the short circuit current density ( J SC ) and fill factor (FF) of PSC devices increase significantly with the improvement of film quality, when the concentration of CPIC is 0.5 mg mL −1 . These made the efficiency of the devices increase from 16.16 % to 18.19 %. Meanwhile, the introduction of the benzene ring in CPIC can improve the stability of the PSC devices. After aging at room temperature and 50 % humidity for 30 days, the device added with CPIC retained 61.9 % of the initial PCE. This work proves that using CPIC as an additive is an effective method to achieve efficient and stable PSCs.
研究领域:
材料科学
·
可再生能源
·
太阳能电池
·
化学
✓ 已验证
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Chen Zhang,Haohao Wu,Fangqin Cheng,Jianfeng Li
Nonradical advanced oxidation has a distinctive excellent selectivity and reactivity. The fine-tuned O/N basic functional groups play a distinguishing role in the occurrence of nonradical pathways. However, it remains debatable regarding the principal basic species and their contribution. Consequently, identification of preferred basic sites and the correlation with the triggered activation mechanism need to be further clarified. In this study, the hydrothermal and thermal annealing method were adopted to construct heterogeneous basic sites on three-dimensional graphene (3D GN), and the activity of peroxydisulfate (PDS) activation was systematically assessed by humic acid(HA)abatement. Herein, the significantly improved catalytic capability (up to 80 %) of 3D GN-NH 3 ⋅H 2 O was acquired, more than 2 times compared to that of 3D GN-NH 3 . The added I D/I G value of 3D GN-NH 3 ⋅H 2 O from 1.05 of 3D GN to 1.08 indicated that it is less graphitized and has more structural defects. Notably, the hydrothermal modification of NH 3 ⋅H 2 O enhanced both the basic oxygen and nitrogen groups (C = O/pyrrolic-N, pyridine-N). A positive correlation was displayed between the integrated basic sites ratio (34.2–71.7 %) and reaction rate (0.169–0.442 min −1 ) based on quantitative calculation. Moreover, the increased content of basic sites and defective sites on 3D GN-NH 3 ⋅H 2 O was responsible for the hydrophobic interaction and 1 O 2 generated in nonradical pathways. The most reactive basic site is the pyrrolic-N which was illustrated by density functional theory (DFT) calculations. Furthermore, a possibly involved nonradical activation mechanism of 3D GNs/PDS was explored. The challenges and prospects of PDS advanced oxidation activated by carbon catalyst are evaluated. This work provides insights into a facile protocol for engineering a carbon catalyst to drive efficient PDS activation in the remediation of water environmental pollutants.
研究领域:
环境化学
·
材料科学
·
催化化学
·
水污染治理
·
碳材料
·
高级氧化技术
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）