JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
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2024
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IF 11.2
Chi Cao,Jinshuo Li,Linfeng Zhang,Yang Hu,Lin Zhang,Wensheng Yang
Herein, a new type of two-dimensional (2D)/2D Ti 3 C 2 /TiO 2 heterojunction was developed for efficient photocatalytic nitrogen reduction reaction (NRR), in which TiO 2 nanosheets (TiO 2 Ns) were designed as the main catalyst, while Ti 3 C 2 MXene served as the co-catalyst. Experimental and theoretical results revealed that Ti 3 C 2 MXene introduced electron-rich unsaturated Ti sites, serving as highly active sites for both the adsorption and activation of N 2 on the Ti 3 C 2 /TiO 2 heterojunction. Furthermore, the 2D/2D Ti 3 C 2 /TiO 2 heterostructure greatly promoted the directional separation and transfer of charge carriers, facilitated by the internal electric field. This structural feature enabled the spatial separation of the N 2 reduction and H 2 O oxidation half-reactions on the distinct surfaces of Ti 3 C 2 (001) and TiO 2 (001), consequently reducing the reaction energy barrier for each respective process. The synergistic effects arising from the interface and surface interactions within the heterojunction conspicuously improved the photocatalytic NRR activity. As a result, the optimized Ti 3 C 2 /TiO 2 heterojunction exhibited a high NH 3 production rate of 24.4 μmol g -1 h -1 in the absence of sacrificial agents, representing a remarkable 12.8-fold increase compared to individual TiO 2 Ns. This work provides new insights into rational design of high-performance heterogeneous photocatalysts and offers a deeper understanding of the mechanism underlying surface active sites in the photocatalytic NRR process.
研究领域:
材料科学
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催化化学
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
ENERGY
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2024
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IF 9
Shuai Guo,Yu Wang,Li Yang,Baizhong Sun,Hongwei Qu,Xingcan Li,Deng Zhao
The study used ReaxFF MD (Reactive Force Field Molecular Dynamics) to investigate the migration behavior and mechanisms of nitrogen in the pyrolysis process of biomass, specifically focusing on the effect of the alkali metal potassium on the main nitrogen-containing substance, proteins. This research primarily centers on the conversion mechanisms of nitrogen in the three-phase products (char, tar, and gas) during the pyrolysis of proteins, as well as the impact on NH 3 formation. The findings reveal several key insights: First, the introduction of potassium significantly enhances the cleavage activity of protein macromolecules by promoting the breaking of carbon-carbon and carbon-nitrogen bonds, which accelerates the degradation process of protein molecules and subsequently increases the conversion rate of nitrogen from proteins to the nitrogen in char, tar, and gas. Second, the addition of potassium alters the sources of gaseous nitrogen (gas-N); initially derived mainly from the secondary cracking of tar nitrogen (tar-N), gas-N predominantly originates from the conversion of char nitrogen (char-N) under the influence of potassium. Lastly, the introduction of potassium affects NH 3 production by significantly altering the trend of nitrogen-hydrogen bond variation during the pyrolysis of proteins. This is primarily attributed to potassium's facilitation of dehydration reactions, which disrupt nitrogen-hydrogen bonds during protein pyrolysis. Additionally, it allows NH 3 produced in the later stages of pyrolysis to participate in the formation of other nitrogen-containing compounds, particularly HCN. Potassium also promotes the dehydrogenation of the large number of HCN molecules generated during protein pyrolysis, forming CN radicals that subsequently react with NH 3 to produce new compounds. This is the main reason for the variation in NH 3 yield.
研究领域:
能源与环境科学
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化学工程
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计算化学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2020
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IF 10.652
Ying Liu,Hongye Bai,Qianxiao Zhang,Yajie Bai,Xuliang Pang,Fagen Wang,Yingchen Yang,Jinrui Ding,Weiqiang Fan,Weidong Shi
Photoelectrochemical N 2 reduction reaction (PEC NRR) into chemical energy source is a promising technique for solving environmental challenges and the energy crisis, which depends on the exploration of p-type photocathodes. Cu 2 O is a p-type semiconductor, which can be applied as a photocathode for PEC NRR. However, the adsorption and activation ability of N 2 over the pristine Cu 2 O is still not ideal, causing the overall efficiency far below the theoretical value. In this work, we first proposed a feasible strategy to in-situ modify the surface of Cu 2 O with Cu-MOF, and the Cu-MOF/Cu 2 O heterostructure exhibited the significantly boosted NH 3 production rate (7.16 mmol/m 2 /h). The ultra-thin Cu-MOF film takes a nature of porous structure and unsaturated Cu sites, contributing to a favorable interface environment for the adsorption and activation of N 2 . The N 2 temperature programmed desorption and contrast photocurrent curves revealed the desirable selectivity for PEC NRR, and the isotope NMR further confirmed the accuracy of NH 3 evolution process. Therefore, the organic–inorganic hybrid systems built from Cu-MOF and Cu 2 O would offer a new insight for establishing the efficient PEC NRR system.
研究领域:
材料科学
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环境科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
Sustainable Materials and Technologies
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2024
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IF 8.6
Lei Guo,Yan-He Chen,Li-Mei Xu,Xiao-Lu Chen,Jin-Qiu Shen,Jian-Yong Zhang,Zhen-Jiang Liu
Herein, a fern-like p-n heterojunction by anchoring Ni 3 Fe-LDH nanoplates onto Co 3 O 4 nanoneedles have been optionally constructed. Essentially, p-n heterojunction ensured to induce strong built-in electric field, and inherit interfacial electron redistribution. Based on their compatible and well-matched electronic band structures, a staggered type-II photo-generated electron/holes transfer pathway have been elaborated by density functional theory calculation (DFT), in situ irradiation X-ray photoelectron spectroscopy (XPS), and fluorescent decay. This band bending and charge migrating module conferred the architecture with strong redox ability, sufficient exciton dissociation, and admirable optoelectronic characteristics. Moreover, the heterostructure acquired broad absorption spectrum to exhibit outperforming photocatalytic effect. Totally, this electron redistribution at the hierarchical interface, a type-II scheme charge-transfer pathway and the oxygen defects would lead to high efficiency in solar light assisted N 2 reduction. Typically, Co@Ni 3 Fe-2 catalyst exhibited the highest NH 3 production rate of 16.15 μg h −1 mg cat. −1 and Faraday efficiency (FE) of 31.57% at −0.6 V vs. RHE in 0.1 M Na 2 SO 4 solution. Fortunately, with light exposure, the NH 3 production rate and FE could increase by 27.9% and 18.1% than that under dark. This work would provide a plausible attitude towards the design of high efficient photocatalyst for artificial photosynthesis with multi-functionalized coupling effect.
研究领域:
材料科学
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催化
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光化学
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理论化学
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
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2023
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IF 5.3
Xiao Tan,Yiming Zhou,Suitao Qi,Guangxu Cheng,Chunhai Yi,Bolun Yang
As one of the important atmospheric pollutants, the removal of NO in flue gas at low temperatures is still a severe challenge. Selective catalytic reduction (SCR) with urea is an effective method for NO removal at low temperatures. Herein, through directly loading urea, an Fe-modified Mn-based molecular sieve catalyst with good low-temperature urea-SCR activity was prepared by a stepwise impregnation method. The results show that with a mass ratio of Mn/Fe of 10:0.5 and a calcination temperature of 500 °C, the catalyst loaded with 15 wt % urea had the highest catalytic activity of 98.5% at 250 °C. Online mass spectrometry results show that NH3 formed from the decomposition of urea reacts with NO when the temperature is above 150 °C, while urea directly reacts with NO below 150 °C. The density functional theory calculation demonstrates that the doping of Fe weakens the strength of the Mn–O bond in MnO2, which makes NO easier to combine with lattice oxygen to oxidize into NO2, thereby promoting the whole urea-SCR reaction. This work provides an overall perspective and theoretical support for the design of urea-SCR catalysts over a wide temperature range.
研究领域:
环境科学
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催化
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大气污染控制
✓ 已验证
产品关联
DOI
高影响因子
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