Journal of Materials Chemistry A
·
2023
·Vol. 12
·期 4
·2349-2358
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IF 11.9
Kefan Liu,Zhaoyu Wang,Guanqi Wang,Xinyi Zhang,Ping He,Yuhui Huang,Zijian Hong,Haiwang Wang
To enhance the photocatalytic hydrogen evolution reaction (HER) activity and stability of barium–strontium–titanate (Ba0.7Sr0.3TiO3, BST), niobium (Nb5+) donor doped BST (Ba0.7Sr0.3Ti1−xNbxO3) photocatalysts were synthesized via a sol–gel assisted solid phase method. It was found that the introduction of Nb5+ expands the lattice and impedes grain growth. In the mechanism of enhancing photocatalytic performance, on one hand, the doped Nb5+ ions generate two types of defects in the lattice of BST, which form defect dipoles to impede electron–hole recombination and improve the stability of photocatalytic performance. On the other hand, the temperature stability test of the dielectric constant shows that appropriate doping of Nb5+ ions will enhance the stability of carrier concentration in BST, thereby exhibiting superior HER activity. In terms of band structure, experiments and Density Functional Theory (DFT) confirmed that the doping of trace amounts of Nb5+ has a very weak influence on the band structure. Additionally, the photocatalytic hydrogen evolution of 1% Nb doped Ba0.7Sr0.3TiO3 was 16.2% higher than that of Ba0.7Sr0.3TiO3.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2023
·
IF 7.2
Zhijun Wang,Huazhou Zhang,Zongbiao Ye,Ge He,Che Liao,Jiyou Deng,Guangjiu Lei,Guoyao Zheng,Kun Zhang,Fujun Gou,Xinchun Mao
Dielectric barrier discharge (DBD) plasma-assisted ammonia decomposition reaction was investigated to produce carbon-free hydrogen for fuel cell applications . Mo 2 N catalyst was synthesized and applied for catalytic ammonia decomposition in different reaction modes. The synergistic effect of using Mo 2 N catalyst in combination with DBD plasma resulted in near complete conversion of NH 3 decomposition at specific energy input (SEI) of 39.6 kJ L −1 , giving an energy efficiency of 6.1 mol·kWh −1 for H 2 production. The particle size of Mo 2 N catalyst was discovered to affect the plasma-catalytic performance for NH 3 decomposition, with Mo 2 N-powder catalyst showing higher reactivity compared with Mo 2 N-particle catalyst. The plasma diagnostic results showed that, compared to the filamentary discharge with Mo 2 N-particle catalyst, the Mo 2 N-powder catalyst packing lead to a predominant surface discharge; such localized surface discharges might contribute to a facile transportation of reactive species from the plasma phase to the catalyst surface , thus leading to higher plasma-catalytic performance.
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ACS Applied Energy Materials
·
2023
·
IF 6.4
Wenrui Cao,Zuoli He,Meng Dai,Guangzhao Wang,Guohe Huang,Shuguang Wang
The consumption of sacrificial agents is inevitable to improve the separation and utilization of electron–hole pairs in photocatalytic H2 evolution, which is contrary to the current vision of carbon neutrality and carbon peak. Here, bimetallic sulfides composed of highly dispersed Cu-doped ZnS composites were proposed, exhibiting an optimal H2 evolution activity of over 1569 μmol/g at 2 h (0.5 g/L catalyst) under visible light irradiation at pH = 3 with zero sacrificial agents or cocatalyst consumption, which is approximately 21 times higher than that of pure ZnS. A series of advanced characterizations indicate that the Cu atoms have been doped into the ZnS lattices, exposing a CuS (101) facet on the surface of the ZnS (111) facet. This results in a narrower energy bandgap (Eg = 2.6 eV) in optimal bimetallic sulfides (ZCS0.1), which is beneficial for absorbing more visible light. In particular, the introduction of Cu induces a nonequilibrium charge distribution on the ZCS0.1 surface, thereby boosting the separation and migration of photoinduced carriers. According to theory calculation (DFT) results, the hydrogen adsorption free energy (ΔGH) of ZCS0.1 is reduced than that of pure ZnS, facilitating the efficient reduction of H+/H2O around the electron accumulation regions and oxidation of H2O around the photogenerated hole (h+) regions. The modulation of the surface electronic structure is significant for effectively separating and utilizing photoinduced carriers under natural conditions without the consumption of sacrificial agents.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2023
·
IF 7.2
Lei Dai,Peng Fu,Jieming Chen,Fazhe Sun
The band gap width has always been the main reason for the low photocatalytic performance of TiO 2 semiconductors. “Band gap engineering” is often used to change the band gap width of TiO 2 . On this basis, the impurity band gap was induced below the TiO 2 conduction band by regulating N element. What's interesting was that N element adjusted the valence state of adjacent Ti element and caused the generation of oxygen vacancy . This is due to the extraction of neutral oxygen atoms, resulting in electron transfer to the Ti cation band structure . The 300-N-T catalyst exhibited the best photocatalytic hydrogen production performance under visible light, which was 307.65 μmol/(g·h) and was 61.53 times higher than that of anatase. And the concentration of Ti 3+ defects and oxygen vacancy reduced with decreasing of N content in TiO 2 . According to Kubelke Munk formula, the band gap of 300-N-T photocatalyst was narrowed to 2.73 eV, which indicated that there are impurity energy levels near the CB and VB of TiO 2 material. The Ti 3+ ions as the active site of the photocatalytic reaction was confirmed by instantaneous photocurrent response and EIS characteristic. This study revealed the structure-activity relationship between the content of N element, Ti 3+ ions and oxygen vacancy in TiO 2 materials, as well as the decisive process of defect induced visible light catalysis.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2019
·
IF 4.084
Qixiao Gai,Xiaochun Zheng,Wenjun Liu,Quanli Dong,Yingying Wang,Renxi Gao,Shoutian Ren
Visible-light photocatalytic water splitting for hydrogen evolution has attracted tremendous attention in past decades, but it still suffers from low solar-hydrogen conversion efficiency. In this paper, two-dimensional (2D) CdS was synthesized by the hydrothermal method , and 2D CoP nanosheets were synthesized by successive hydrothermal, oxidation and phosphodation process. Then 2D-2D CdS–CoP photocatalysts were formed by ultrasonically dispersing the mixed solution of CdS and CoP, and their heterostructure was confirmed by transmission electron microscopy , X-ray photoelectron spectroscopy, fluorescence spectrometer and so on. CdS–CoP with 2% CoP loading amounts exhibits a maximum photocatalytic performance of 56.3 mmolg −1 h −1 under visible light irradiation , which is 11.3 times as high as bare CdS. The enhanced photocatalytic performance of CdS–CoP should be due to the following two points: (1) high catalytic activity of CoP; (2) highly efficient separation and transfer of electron-hole pairs photogenerated in CdS due to the synthesized 2D-2D heterostructure.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2019
·
IF 4.084
Kaifeng Wang,Qi Wu,Xiaoming Yan,Jiafei Liu,Li Gao,Lei Hu,Ning Zhang,Yu Pan,Wenji Zheng,Gaohong He
High-performance anion exchange membranes (AEMs) are in need for practical application of AEM fuel cells. Novel branched poly(ether ether ketone) (BPEEK) based AEMs were prepared by the copolymerization of phloroglucinol , methylhydroquinone and 4,4′-difluorobenzophenone and following functionalization. The effects of the branched polymer structures and functional groups on the membrane's properties were investigated. The swelling ratios of all the membranes were kept below 15% at room temperature and had good dimensional stability at elevated temperatures. The branching degree has almost no effect on the dimensional change, but plays a great role in tuning the nanophase separation structure. The cyclic ammonium functionalized membrane showed a lower conductivity but a much better stability than imidazolium one. The BPEEK-3-Pip-53 membrane with the branching degree of 3% and piperidine functionalization degree of 53% showed the best performances. The ionic conductivity was 43 mS cm −1 at 60 °C. The ionic conductivity in 1 M KOH at 60 °C after 336 h was 75% of its initial value (25% loss of conductivity), and the IEC was 83% of its initial value (17% loss of IEC), suggesting good alkaline stability. The peak energy density (60 °C) of the single H 2 /O 2 fuel cell with BPEEK-3-Pip-53 membrane reached 133 mW cm −2 at 260 mA cm −2 .
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CARBON
·
2019
·
IF 7.466
Hongfei Zhao,Shuaijun Wang,Fengting He,Jinqiang Zhang,Lin Chen,Pei Dong,Zhaoxin Tai,Yongqiang Wang,Haitao Gao,Chaocheng Zhao
Hydroxylated multi-walled carbon nanotubes modified with a carbon nitride nanobelt (HCNT/CNN) were successfully fabricated by using combined solvothermal and ultrasonic methods to improve both tetracycline hydrochloride (TC) degradation and H 2 evolution. The well-designed photocatalysts exhibited a wide light absorption range, low photoluminescence (PL) intensity, high photocurrent , and small electrochemical impedance spectroscopy (EIS) arc; these properties significantly enhanced the overall photocatalytic efficiency. At the optimal loading of HCNT (0.05 wt%), the resulting HCNT/CNN exhibited the highest TC photocatalytic degradation rate , and the H 2 production rate reached 175.5 μmol g −1 h −1 . Compared to the multi-walled carbon nanotube modified carbon nitride nanobelt, the TC photocatalytic degradation rate and H 2 production rate of HCNT/CNN increased by factors of 3 and 4.2, respectively. This significantly enhanced performance can be ascribed to the formation of hydrogen bonds between HCNT and CNN, which facilitates the electron transfer from the CNN to the HCNT surface, thereby accelerating the separation of photogenerated charge carriers. Moreover, the possible mechanism of the improved photocatalytic performance for the HCNT/CNN composites was proposed. This study provides the guidance for the design of novel carbon nitride nanobelt-based photocatalysts for wastewater purification and H 2 evolution.
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SURFACE REVIEW AND LETTERS
·
2018
·
IF 0.734
MAO ZHOU,YUQING MIAO
In the International Space Station, urine is considered something to be treated. However, urine is mainly composed of water and urea, while they have been demonstrated as an excellent hydrogen carrier for sustainable energy supply. Through the simple chemical coprecipitation and hydrothermal reaction, the needle-like NiMoO 4 crystals were synthesized with the average width around 500 nm and length up to 4 μ m. The resulted products were thoroughly characterized by scanning electron microscopy, energy dispersive X-ray spectrometry, X-ray diffraction, Fourier-transform infrared spectroscopy and ultraviolet–visible spectrum. The needle-like NiMoO 4 crystals exhibited excellent electrocatalytic oxidation toward urea at anode in alkali solution, leading to the increased performance of hydrogen evolution reaction at cathode with the lower electrochemical potential and energy consumption required to drive the reaction. The high electrocatalysis of the needle-like NiMoO 4 crystals toward urea oxidation reveals their great potential for future application to clean the urine/urea-rich wastewater and to produce hydrogen in space station and environmental wastewater.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2018
·
IF 3.779
Lijing Wang,Gan Jin,Yanhong Shi,Hao Zhang,Haiming Xie,Bai Yang,Haizhu Sun
Two-dimensional (2D) ZnS-SnS 2 porous nanosheets are designed as clean and low cost photocatalysts for water splitting. The composites successfully combine high photoelectron reduction potential of ZnS with the sufficient sunlight harvesting ability of SnS 2 . Moreover, SnS 2 acts as an effective electron transfer medium from ZnS to SnS 2 due to the construction of quasi-type II structure. This greatly promotes the transfer of electron-hole pairs and effectively inhibits their recombination. Especially, the unique porous nanosheets structure maintains them high specific surface area and countless reactive sites, which increases the reactants' contact area and facilitates the migration of carriers upon photocatalysis . This further suppresses the charge recombination and improves the photocatalysts' stability. As a result, an optimized specific surface area of 246.7 m 2 g −1 and photocatalytic H 2 generation rate of 536 μmol h −1 g −1 are achieved in the absence of a surfactant and co-catalyst, which is 10 times higher than ZnS and 17 times higher than SnS 2 . In addition, the porous nanosheets have fairly good photocatalytic stability and can be reused at least five cycles without obvious changes in activity and structure. This work successfully presents the potential of ZnS and SnS 2 -based photocatalyst for clean and low cost hydrogen production from water splitting.
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CHEMISTRY-A EUROPEAN JOURNAL
·
2023
·Vol. 29
·期 18
·e202203152
·
IF 4.3
Yan Long,Jie He,Hang Zhang,Yingkang Chen,Kang Liu,Junwei Fu,Hongmei Li,Li Zhu,Zhang Lin,Andrei Stefancu,Emiliano Cortes,Mingshan Zhu,Min Liu
Graphical Ag/Al 2 O 3 catalytic controllable synthesis of N-monomethylated amines by using CO 2 /H 2 as C 1 source has been demonstrated in a first example. The reactivity of methylated amines was reduced by the heterolytic dissociation of H 2 over the catalyst, and hence conversion of various amines to corresponding monomethylated amines was enabled with excellent selectivity. The selective synthesis of monomethylated amines with CO 2 is particularly challenging because the formation of tertiary amines is thermodynamically more favorable. Herein, a new strategy for the controllable synthesis of N-monomethylated amines from primary amines and CO 2 /H 2 is explored. First-principle calculations reveal that the dissociation of H 2 via an heterolytic route reduces the reactivity of methylated amines and thus inhibit successive methylation. In situ DRIFTS proves the process of formation and decomposition of ammonium salt by secondary amine reversible binding with H + on the Ag/Al 2 O 3 catalyst, thereby reducing its reactivity. Meanwhile, the energy barrier for the rate-determining step of monomethylation was much lower than that of overmethylation (0.34 eV vs. 0.58 eV) means amines monomethylation in preference to successive methylation. Under optimal reaction conditions, a variety of amines were converted to the corresponding monomethylated amines in good to excellent yields, and more than 90 % yield of product was obtained.
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CHEMICAL PHYSICS LETTERS
·
2022
·
IF 2.719
Peng Guan,Bin Yang,Jianyong Liu,Hang Yin,Jutao Jiang,Laizhi Sui,Songqiu Yang
It is very necessary to develop stable and cheap photocatalysts without precious metals, but they can significantly increase the photocatalytic activity. Herein, we designed and fabricated novel rare-earth cerium doped C 3 N 4 (Ce-C 3 N 4 ) for boosting photocatalytic H 2 evolution. The chemical structure, morphology, photoelectrochemical and optical properties of the as-prepared Ce-C 3 N 4 was tested through a range of characterization. The as-prepared 0.01Ce-C 3 N 4 exhibited superior photocatalytic hydrogen evolution activity (≈2.6 fold) than pristine C 3 N 4 . Its excellent photocatalytic activity result from efficient charge separation and an extended carrier lifetime. This work highlights the importance of rare earth element doping for devising of highly efficient and stable photocatalysts.
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ACS Applied Nano Materials
·
2022
·
IF 6.14
Hao Yu,Minghao Dou,Shuang Wang,Yuye Cheng,Zhiqiang Li,Hongyu Shao,Mengjie Yao,Xinrui Wang,Yanyan Chen,Shenjie Li
Although quantum dots (QDs) have unique properties that are different from conventional semiconductors, their photocatalytic activity and stability are far from expectations, and the preparation of semiconductor composites has become an important means to improve their photocatalytic hydrogen production performance. A convenient and safe coordination-assisted self-assembly method was used to encapsulate QDs into metal–organic frameworks and further formed AgInS2@ZIF-8/ZnS nanostructures by converting part of ZIF-8 into ZnS composite materials, which enhanced their photocatalytic hydrogen production performance and cycling stability. The results show that AgInS2@ZIF-8/ZnS nanocomposites have the highest photocatalytic activity (the average hydrogen production reaches 9.79 mmol·g–1·h–1; λ > 420 nm) after 6 h of sulfurization, which is far greater than that of AgInS2 QDs. Compared with the AgInS2@ZIF-8 composite, their performance is improved by nearly 10 times. In conclusion, a simple, safe, and easily-controllable method is used to prepare a novel and efficient photocatalytic material, which provides a new idea about the rational design of novel QD photocatalytic composites.
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