ACS Applied Materials & Interfaces
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2023
·
IF 9.5
Wenqing Hou,Chen Chen,Diya Xie,Yiming Xu
Metal–organic frameworks (MOFs) as photocatalysts have received increasing attention. In this work, a dual metal-substituted UiO-66-NH2 (Ti/Ce-MOF) containing different Ti/Ce mole ratios (x = 0–2.46) has been prepared via post-synthetic exchange between Ce-UiO-66 and TiCl4, followed by amination. The solid had a high surface area (828–937 m2/g) and a large pore volume (0.451–0.507 m3/g). Under visible light, Ti/Ce-MOF showed x-dependent activity for H2O reduction and oxidation on a film electrode, respectively. However, such a change for H2 evolution in a Na2S/Na2SO3 aqueous solution was observed only after CdS loading. In combination with the photoluminescence and band parameters, we propose that the photoactivity of Ti/Ce-MOF for redox reaction is determined by its ability for electron transfer. Furthermore, there is an interfacial electron transfer from Ti/Ce-MOF to CdS and a hole transfer from CdS to Ti/Ce-MOF, respectively, significantly improving the efficiency of charge separation for redox reactions. This work offers a new insight that Ti substitution benefits the performance of Ce-based MOF.
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高影响因子
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY
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2019
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IF 3.261
Asif Hayat,Fazal Raziq,Muhammad Khan,Ikram Ullah,Mati Ur Rahman,Wasim Ullah Khan,Javid Khan,Akhlaq Ahmad
In this work, we report the fabrication of polypyrrole/g-C 3 N 4 (PPy/g-C 3 N 4 ) nanocomposites via simple wet-chemical method. The photocatalytic activities of the composites are evaluated for water splitting to evolve H 2 , Rhodamine B dye (RhB) and 2,4-dichlorophenol (2,4-DCP) degradation under visible-light. The results reveal that the photocatalytic performance of g-C 3 N 4 for H 2 evolution, RhB dye and 2, 4-DCP degradation are significantly improved after coupling polypyrrole (PPy). Worth noting, the amount optimized (1 wt%PPy/g-C 3 N 4 ) photocatalyst showed highest photoactivity compared to the other photocatalysts. Further, it is confirmed by means of radical trapping experiments that superoxide radical (O 2 − ) is the dominant specie involved in the degradation of pollutants over PPy/g-C 3 N 4 nano-composites. Moreover, clear photocatalytic reactions for H 2 evolution and pollutants degradation are proposed. This work would help us to deeply understand the reaction mechanism and will provide feasible routes to fabricate g-C 3 N 4 based highly efficient photocatalysts for energy and environmental applications.
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ChemCatChem
·
2019
·Vol. 11
·期 11
·2657-2666
·
IF 4.495
Jun-Shuai Zhang,Wei-De Zhang
Graphical Let the sun shine ! Photocatalytic hydrogen evolution is an attractive way to convert sunlight to fuel for solving worldwide energy shortage and environment issues. This study demonstrates non-noble photocatalysts consisting cobalt complex and graphitic carbon nitride, in which CoL 2 (SCN) 2 cocatalyst was covalently grafted onto CN. This hybrid exhibits excellent performance towards photocatalytic H 2 generation (272 μmol g −1 h −1 ) from water medium and also presents high stability, which provides a novel way for designing high activity and low-cost photocatalysts for solar H 2 conversion. To develop stable, efficient, non-noble metal-based photocatalysts for water splitting has become a long-standing challenge. Here, cobalt−phenanthroline active species are grafted from metal-free photosensitive carbon nitride nanosheets (CN) by dehydration reaction between pendant amino groups from CN and carboxyl groups of functional phenanthroline ligands for photocatalytic H 2 evolution in water medium. The cobalt complex unit serves as a cocatalyst to accelerate separation and transferring of photoexcited charge carriers, and reduce overpotential for H 2 evolution. The hybrid catalyst without any precious metals exhibits excellent performance of H 2 evolution (272 μmol g −1 h −1 ) and high stability during photocatalytic reaction. The finding not only develops a facile way to prepare high-performance low-cost photocatalysts for photocatalytic H 2 production, but also provides a new insight into optimizing the interface between cocatalysts and photosensitizers for photocatalytic reaction by grafting active sites directly from semiconductors.
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ACS Sustainable Chemistry & Engineering
·
2018
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IF 6.14
Jiajia Feng,Dingke Zhang,Hongpeng Zhou,Mingyu Pi,Xiaodeng Wang,Shijian Chen
Fabricating heterostructures to promote the charge separation and doping heteroatom to modulate the band gap of the photocatalysts have been regarded as effective strategies to improve the photocatalytic performance. However, it is still an unresolved issue of doping element and fabricating heterostructures with good contact at the same time. In this study, P nanostructures/P doped graphitic carbon nitride composites (P@P-g-C3N4) were successfully composited by a solid reaction route. Various structural characterizations, including X-ray adsorption near edge structure, indicate that P has been doped into g-C3N4 and P nanostructures were directly grown on g-C3N4 to form heterostructures. As expected, the intimate contacted heterostructured composites exhibit much enhanced light absorption and high-efficiency transfer and separation of photogenerated electron–hole pairs, and consequently, the composites also possess the superior photocatalytic performance in the rapidly degrading RhB and an efficient H2 production rate of 941.80 μmolh–1g–1. Systematical studies combining experimental measurements with theoretical calculations were carried out to expound the underlying reasons behind the distinct performance. This study pave a one-step way to synthesize earth abundant element C, N, and P as novel photocatalysts for photochemical applications.
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Catalysis Science & Technology
·
2018
·Vol. 8
·期 11
·2853-2859
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IF 5.365
Ya-Nan Liu,Xiao Zhou,Cong-Cong Shen,Zhi-Wei Zhao,Yi-Fan Jiang,Liu-Bo Ma,Xiao-Xiang Fang,Zeb Akif,Tuck-Yun Cheag,An-Wu Xu
Herein, a polymeric graphitic carbon nitride (for simplicity, g-C3N4) photocatalyst has been identified as a promising material for hydrogen production from water due to its comparatively low cost and facile modification of its electronic structure. However, to date, how to speed up the transfer rate of photogenerated charges, especially hole transfer rate, still remains a formidable challenge. Herein, a novel system of g-C3N4/1,1′-ferrocenedicarboxylic acid (FcDA) composites was developed for efficient visible light-driven H2 evolution, in which the redox mediator FcDA served as hole-transport molecules and platinum (Pt) acted as an electron sink. The FcDA molecules are anchored onto g-C3N4 by hydrogen-bonding interactions between the carboxylic groups and amino groups as well as π–π interactions between aromatic FcDA and graphitic C3N4. The matched energy-levels between g-C3N4 and FcDA facilitate photogenerated hole transfer from the g-C3N4 valence band to FcDA that results in the formation of FcDA+ radicals, and thus, photoinduced electrons and holes are efficiently separated. Due to the additional charge separation pathway, enhanced hole transfer kinetics, and the extremely rapid intermolecular radical reactions, charge recombination is effectively suppressed; therefore, more electrons can be released for hydrogen production. Under optimal experimental conditions, the developed g-C3N4/FcDA composite with 4 wt% FcDA exhibits high water splitting activity with a H2 evolution rate of up to 77.91 μmol h−1, which is nearly 6 times that of bare g-C3N4 (13.18 μmol h−1). Moreover, the obtained g-C3N4/FcDA photocatalyst displays excellent stability, and there is no obvious decrease in the H2-production rate after five test cycles. Thus, we anticipate that our simple modification strategy will offer an avenue to merge the polymeric g-C3N4 photocatalyst with surface organometallic chemistry for high-efficiency solar-to-fuel conversion.
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高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2017
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IF 3.582
Zongxiong Xu,Hao Fu,Tian Wen,Lei Zhang,Jian Zhang
Titanium-oxo clusters (TOCs) are important model complexes and potential precise single-source precursors of TiO 2 materials. We report here a series of TiO 2 samples derived from TOCs with the same wheel-like Ti 8 O 8 clustercore but different stabilizing ligands. Our results demonstrate that the ligands on TOCs not only influence the phase-transition during themolysis, but more importantly tune the photocatalytic H 2 evolution activities of the obtained TiO 2 materials. Through 500 °C calcination , the nanosized Ti 8 O 8 cluster stabilized by organic benzoate ligands gives rise to a TiO 2 sample with H 2 production rate of 611 μ mol/h/g. When the stabilizing ligands are changed to inorganic SO 4 2− , a significant improvement of H 2 evolution activity has been achieved, resulting in a 7-times higher value of 4527 μ mol/h/g. This work provides a new strategy to produce TiO 2 with enhanced and tunable photocatalytic activities from titanium-oxo cluster precursors.
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高影响因子
PROCESS SAFETY AND ENVIRONMENTAL PROTECTION
·
2024
·
IF 6.9
Fangjun Wang,Shiyi Chen,Shubo Chen,Pengxing Yuan,Lunbo Duan,Wenguo Xiang
As the interest in environmentally-friendly energy processes increases, many studies have been focused on producing hydrogen as an alternative energy carrier via catalytic reaction processes. Sorption enhanced water gas shift (SEWGS) that combines WGS and in situ CO 2 removal is a promising technology for high-purity H 2 production and CO 2 capture. In this study, Fe/Ce-modified CaO-Ca 12 Al 14 O 33 bi-functional porous nanotubes were synthesized in one step by template method and applied for H 2 production from SEWGS process. The unique porous nanotube structure fully exposes the catalytic active sites and facilitates the gas-solid transport, resulting in the excellent H 2 production and CO 2 capture performance in SEWGS/regeneration cycles. The introduction of Ce enhances the basicity of the nanotube material, thereby increasing the affinity for CO 2 . The interaction of Fe-Ce improves the redox capability of Fe 2+ and Fe 3+ , which is beneficial to the conversion of CO. In addition, the formed Ca 2 Fe 2 O 5 and Ca 2 CeO 4 both increase the concentration of oxygen vacancies , further enhancing the SEWGS reactivity of the material. The optimal molar ratio of Fe/Ce/Al/Ca is 10/3/10/100, and the CO conversion, H 2 concentration, CO 2 capture capacity of the Fe/Ce-modified bi-functional material were 76.9 %, 70.1 % and 83.2 % after 20 cycles. The effect of Fe/Ce doping on CaO-based materials was investigated at the molecular level using density functional theory (DFT). The results demonstrate that the addition of Ce can effectively maintain the stable structure of Fe-CaO-based materials. The modification of Fe/Ce is expected to promote efficient H 2 generation from CaO-based materials through the SEWGS process.
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Nano Energy
·
2016
·
IF 11.553
Lihua Yao,Ding Wei,Yuanman Ni,Dongpeng Yan,Changwen Hu
The construction of new semiconductor photocatalysts toward high-efficiency splitting water has played an important role in developing sustainable and clean hydrogen energy . In this work, new type of micro/nano-sized hybrids were synthesized based on the assembly of 0D Cd 0.5 Zn 0.5 S quantum dots (QDs, size: ca. 5 nm) onto 2D graphitic carbon nitride ( g -C 3 N 4 ) ultrathin microribbons (thickness: ca. 4 nm) via an in-situ growth hydrothermal method . The Cd 0.5 Zn 0.5 S 32 wt%@C 3 N 4 composite exhibits the highest visible-light-driven H 2 -generation rate of 33.41 mmol h −1 g −1 without any noble-metal as cocatalyst , and the apparent quantum efficiency is 46.65% at 450 nm. Such H 2 -generation rate is higher than the pristine g -C 3 N 4 and Cd 0.5 Zn 0.5 S by a factor of 27.39 and 9.18 respectively, which is significantly enhanced compared with most as-reported noble-metal-free semiconductor catalysts to date. In addition, compared with the pristine Cd 0.5 Zn 0.5 S, the photocatalytical stability of Cd 0.5 Zn 0.5 S QDs@C 3 N 4 is highly improved. The enhanced H 2 -generation performance can be attributed to the well-matched energy level and strong electronic coupling between two components at the g- C 3 N 4 interface as well as enhanced visible-light absorption. The uniform dispersion of Cd 0.5 Zn 0.5 S QDs onto the g -C 3 N 4 ultrathin microribbons also facilitates the depression of electron-hole recombination from potential aggregation of Cd 0.5 Zn 0.5 S. Therefore, this work supplies an effective way to obtain promising 2D micro/nanostructures for high-efficiency visible light-induced H 2 -generation.
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Nano Energy
·
2016
·
IF 11.553
Zongwei Mei,Bingkai Zhang,Jiaxin Zheng,Sheng Yuan,Zengqing Zhuo,Xianguang Meng,Zonghai Chen,Khalil Amine,Wanli Yang,Lin.-Wang Wang,Wei Wang,Shufeng Wang,Qihuang Gong,Jun Li,Fu.-Sheng Liu,Feng Pan
Cu-doping into Zn 1−x Cd x S can greatly enhance the photocatalytic H 2 evolution from water splitting under visible-light irradiation. However, it is still controversial for how the Cu-dopant improves this performance. Here, we report that appropriate Cu-doped Zn 0.5 Cd 0.5 S nanocrystals reach 21.4 mmol/h/g of H 2 evolution rate without cocatalyst in the visible-light region, which is also 2.8 times as high as that of the undoped counterpart, and the corresponding apparent quantum efficiency is 18.8% at 428 nm. It is firstly confirmed that the Cu 2+ changes into Cu + after being doped by soft X-ray absorption spectroscopy (sXAS). We theoretically propose that the transformation of 2Cu 2+ to 2Cu + results in one adjacent S 2 − vacancy (V S ) in host during the doping process, while the Cu + -dopant and V S attract the photoexcited holes and electrons, respectively. Accordingly, the photocatalytic activity is improved due to the enhanced separation of photoexcited carriers accompanied with the enhanced light absorption resulting from the Cu + -dopant and 2Cu + /V S complex as possible active site for photocatalytic H 2 evolution.
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ChemCatChem
·
2016
·Vol. 8
·期 22
·3527-3535
·
IF 4.724
Feng-Yun Su,Cheng-Qun Xu,Yu-Xiang Yu,Wei-De Zhang
Graphical Carbon self-doped g-C 3 N 4 nanosheets were synthesized in a simple way by a one-step calcination of a ternary supramolecular network of cyanuric acid, ethylene glycol (EG), and melamine. Carbon doping resulted in a distorted framework and induced the activation of n–π* electronic transitions of the C-g-C 3 N 4 nanosheets. The obtained C-g-C 3 N 4 displayed high activity for photocatalytic H 2 evolution owing to the extended light harvesting and faster separation of photogenerated electrons and holes. This paper reports a facile one-pot synthesis strategy to prepare carbon self-doped g-C 3 N 4 (C-g-C 3 N 4 ) nanosheets by using supramolecular networks consisting of cyanuric acid, ethylene glycol (EG), and melamine (CEM) bonded through hydrogen bonding as the thermal polycondensation precursor, in which EG serves as a solvent for cyanuric acid and melamine, and as a source of the doped carbon simultaneously. The threedimensional structure of CEM resulted in the distortion of C-g-C 3 N 4 , which is capable of motivating the n–π* electronic transition involving the N lone pairs to give an additional absorption region from 450 to 600 nm. The hydrogen evolution rate of C-g-C 3 N 4 reaches 73.09 μmol h −1 , which is about 15 times of that over the g-C 3 N 4 obtained from direct thermal polycondensation of melamine owing to its extended light harvesting and faster separation of photogenerated electrons and holes.
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Inorganic Chemistry Frontiers
·
2017
·Vol. 5
·期 1
·258-265
·
IF 4.036
Lili Tan,Yanhong Liu,Baodong Mao,Bifu Luo,Guan Gong,Yuanzhi Hong,Biyi Chen,Weidong Shi
The development of single-component photocatalysts with narrow bandgaps (2.0–3.0 eV) has been one of the most important goals for photocatalytic H2 production, for which I–III–VI multinary sulfides play an important role due to their widely tunable composition-dependent bandgap. However, simultaneous bandgap narrowing and photocatalytic activity enhancement in the I–III–VI sulfides are often difficult to achieve due to increased defect states. Here, a series of Cu–In–Zn–S quantum dots (QDs) were synthesized by a facile hydrothermal method focusing on a more profound understanding of bandgap tuning and the subsequent effect on the photocatalytic process by controlling the Cu content. The bandgap of the QDs can be effectively tuned from 2.90 eV to 1.98 eV with an increasing Cu : In ratio from 0.05 : 10 to 2.5 : 10 and a color change from light yellow to dark red. The QDs show photocatalytic H2 production activity even without any cocatalyst, but it quickly starts to decrease with the Cu/In ratio over 0.1 : 10 (bandgap of 2.59 eV), which highly limits the potential for visible light photocatalysis. Interestingly, Pt-loading effectively enhanced not only the tolerance of Cu incorporation, but also enabled a high H2 production activity even with further bandgap narrowing down to ∼2 eV. The best photocatalytic performance of 456.4 μmol h−1 g−1 was achieved for the Cu : In : Zn ratio of 1 : 10 : 5 with a bandgap of 2.27 eV. This increased tolerance of Cu content may result from a combined effect of charge separation by Pt as the cocatalyst that alleviated the Cu-induced charge recombination. The enhanced charge separation was proved by the photoluminescence quenching of the QDs with the cocatalyst. Electrochemical impedance spectroscopy was further used to study the charge separation properties of this photocatalytic system. This is the first observation of the cocatalyst-enhanced tolerance of Cu resulting from the competition of cocatalyst-induced charge separation and defect-induced charge recombination in multinary sulfides, which provides an interesting view and design guideline for the development of narrow bandgap photocatalysts.
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RSC Advances
·
2014
·Vol. 4
·期 69
·36603-36614
·
IF 3.708
Hongyun Peng,Lingling Gao,Mengjiao Li,Yibin Shen,Qiongqiu Qian,Xia Li
Bio H2 conversion from wetland lignocellulosic biomass is one of the promising alternatives to fossil fuels. Both Phragmites (sp.) and Thalia dealbata are holocellulose-rich and lignin-rich wetland plant biomasses. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) demonstrated alteration of lignocellulosic structures due to hemicelluloses removal by steam explosion (SE) pretreatment, and further disruption of cellulose crystallinity after treatment with SE followed by [Bmim]Cl (SE-[Bmim]Cl). Thermogravimetry/differential thermogravimetry (TG/DTG) revealed an increase in amorphous cellulose and partial delignification in lignocellulosic structures as a consequence of SE-[Bmim]Cl. The pretreatment of both SE and SE-[Bmim]Cl yielded lignocellulosic substrates with improved properties in terms of their conversion into glucose and bio H2. Five-to-ten folds (by SE) and ten-to-twenty folds (by SE-[Bmim]Cl) more glucose was released from the lignocellulosic substrates of both plants than those of contrast samples. Compared to Phragmites (sp.), the greater destruction in lignocellulosic structure of Thalia dealbata as a result of SE and SE-[Bmim]Cl, increased the accessible surface area and disrupted the cellulose crystallinity much more, thus making it more efficient for bio H2 conversion. The bio H2 of 1.97 ± 0.14 mmol H2 g−1 dry weight (DW) was yielded after sludge anaerobic fermentation of Thalia dealbata treated with SE, and it increased to 4.79 ± 0.86 mmol H2 g−1 DW after SE-[Bmim]Cl treatment. For Phragmites (sp.) it was 1.45 ± 0.42 and 2.75 ± 0.76 mmol H2 g−1 DW after SE and SE-[Bmim]Cl pretreatment, respectively. Therefore, SE-[Bmim]Cl pretreatment can be developed for efficiently enhancing bio H2 conversion from wetland plant Thalia dealbata.
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