Nano Research
·
2020
·Vol. 13
·期 12
·3206-3211
·
IF 8.183
Zhang Meng,Hu Zheng,Gu Lin,Zhang Qinghua,Zhang Linghui,Song Qian,Zhou Wei,Hu Shi
A series of carbon-based binary single-atom catalysts of Fe and Ni coordinated by nitrogen are fabricated using a glucose-chelating method. Depending on the Ni/Fe content, they exhibit a wide-range of controllable CO/H 2 ratio from 0.14 to 10.86, which is meaningful to specific chemical processes. The durability of the catalyst is evaluated over an 8-hour period with no significant degradation of activity. The variation of the faradaic efficiency with Ni/Fe content is justified by density-functional-theory based calculation of the reaction barrier in both hydrogen evolution and CO 2 reduction reactions.
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高影响因子
CARBON
·
2020
·
IF 8.821
Kunlin Liu,Ting Yang,Xuewen Zheng,Chengyang Wang,Mingming Chen
Low energy density is a fatal disadvantage of electric double-layer capacitor (EDLC). The improvement of the operation voltage of EDLCs is a more effective method to increase the energy density of EDLCs. When the operation voltage of EDLCs is higher than 2.7 V, the oxygen-containing functional groups on the surface of electrode materials (porous carbon) will decompose or chemically react with the electrolyte, causing significant deterioration of EDLC performance. In this paper, porous carbon with low oxygen content is prepared by using the potassium-assisted carbonization of chlorobenzene in Ar/H 2 mixed gas to improve withstanding voltage characteristic of porous carbon. By constructing a relatively closed and stable pyrolysis environment (employing the nickel crucible with a lid), using the carbonaceous precursor without oxygen atoms (chlorobenzene) and selecting reasonable carbonization operation atmosphere (Ar/H 2 ), the oxygen content of the as-prepared porous carbon (PC-KC-1000) is only 4.02 wt%. When the PC-KC-1000 sample is used as the electrode material of EDLCs, the operation voltage of EDLCs in the TEABF 4 /PC and EMIMBF 4 electrolytes is respectively 3.3 and 3.5 V, and the maximum energy density is respectively 53.5 and 64.4 Wh kg −1 . This strategy provides a new idea for the preparation of porous carbon with low oxygen content.
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高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2020
·
IF 4.939
Jiayan Xue,Lizhen Long,Lin Zhang,Hongtian Luo,Li Yang,Fuchi Liu,Fengzhen Lv,Wenjie Kong,Jun Liu
Synergistic the modulation of photon absorption capability and interfacial charge transfer of the photocatalyst are highly required for developing high-performance heterojunction photocatalysts. The ternary CdS-graphene quantum dots-titanate nanotubes (CdS-GQDs-TNTs) nanocomposite have been prepared by an in situ growth method. The physicochemical characterization reveals that the GQDs are firmly decorated on both inner and outer surface of TNT through the formation of Ti–O–C chemical bonding, and CdS QDs are loaded on the outer surface of TNTs through strong interfacial interaction . The intimate integrated CdS-GQDs-TNTs nanocomposite exhibits much superior photocatalytic performance toward H 2 production compared with binary GQDs-TNTs and pure TNTs photocatalyst, which can be attributed to the combined interaction of the stronger visible light harvesting, the longer lifetime of photogenerated electron−hole pairs, faster interfacial charge transfer rate, fast and long-distance electron transport pass. The interfacial charge transfer mechanism of CdS-GQDs-TNTs ternary composite are proposed based on photoelectrochemical measurements.
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高影响因子
CATALYSIS LETTERS
·
2021
·Vol. 152
·期 4
·1145-1159
·
IF 3.186
Yu Guiyun,Zhao Yefan,Zhang Yulong,Wu Jiaxin,Liu Chao
There are increasing concerns of environmental-pollution and energy issues. Herein, an exfoliation-restacking process was firstly employed to synthesize H + -restacked H + Ti 2 NbO 7 − nanosheets (HTNS), and then heated with melamine at 510 °C to obtain direct Z-scheme layered N-doped H + Ti 2 NbO 7 − /g-C 3 N 4 (TCN) heterojunctions with an increased specific surface area. Two-dimensional (2D) g-C 3 N 4 material was in-situ formed on the surface of HTNS to achieve a layered heterostructure between two components, which could maximize interfacial contact area and minimize interfacial distance for the efficient charge carrier separation. Simultaneously, the surface of HTNS was doped by nitrogen atoms to form visible-light-responsive N-doped HTNS. All TCN x ( x = 1, 2 and 3) composites exhibited the enhanced photocatalytic activity for both hydrogen (H 2 ) production and rhodamine B (RhB) degradation. As an optimal sample, the resulted TCN2 composite exhibited the best photocatalytic efficiency for H 2 production and RhB degradation. The enhanced photocatalytic activity was assigned to the combined effects of layered heterojunction, N-doping and large specific surface area. According to trapping experiments and electron spin resonance (ESR) spectra, the holes (h + ), superoxide (·O 2 − ) and hydroxyl (·OH) radicals were responsible for photocatalytic RhB degradation and especially the ·O 2 − was the key active specie. A possible charge transfer pathway was analyzed in detail. This work will hopefully provide some guidance on designing Z-scheme layered heterojunction photocatalyst systems with highly photocatalytic efficiency. Graphical Abstract Direct Z-scheme layered N-doped H + Ti 2 NbO 7 − /g-C 3 N 4 heterojunction photocatalysts were constructed by a three-step exfoliation-restacking-calcination process, showing the highly photocatalytic efficiency for H 2 production and RhB degradation under visible light due to the synergistic effects of layered heterojunction, N-doping and large specific surface area.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2019
·
IF 8.355
Yanglin Chen,Xueqing Liu,Ling Hou,Xiaorui Guo,Ruiwei Fu,Jianmin Sun
Photocatalytic water splitting for hydrogen production is a brilliant method for utilization of solar energy. Herein, a series of covalent bonding oxygen-doped carbon nitride/graphitic carbon nitride hybrids (O-CN/CN) have been synthesized via solvothermal treatment using cyanuric chloride, cyanuric acid (derived from hydrolysis of cyanuric chloride) and urea-derived graphitic carbon nitride as precursors. In O-CN/CN hybrids, guest O-CN was covalently bonded with incomplete polycondensation –NH x derived from the host CN surface as verified by XRD, FT-IR, XPS and solid-state 13 C MAS NMR spectra. With assistance of Pt co-catalyst, the most efficient O-CN/CN-3 photocatalyst showed the highest H 2 generation rate at 6.97 mmol g −1 h −1 under visible light irradiation (λ > 420 nm) by 12.4 times as that of pristine CN (0.56 mmol g −1 h −1 ). Moreover, the apparent quantum yield (AQY) was estimated as 21.4% at 425 nm irradiation for O-CN/CN-3. The improved photocatalytic performance was ascribed to the extended visible light absorption, the inhibited photo-induced charge carrier recombination and rapid charge carriers transfer that were confirmed by UV–vis diffuse reflectance spectra, photoluminescence spectra, transient photocurrent responses, electrochemical impedance spectroscopy and time-resolved photoluminescence. Moreover, the photocatalytic activity displayed unnoticeable deactivation within five recycles, further verifying that O-CN/CN hybrids were stable for visible-light-driven H 2 evolution. This present work promotes new insights into Z-scheme heterojunction engineering for graphitic carbon nitride.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2019
·
IF 4.084
Zhaohui Huang,Hui Chen,Lei Zhao,Xuan He,Yingying Du,Wei Fang,Weixin Li,Pan Tian
The development of ultraviolet to near-infrared (UV-Vis-NIR) responsive photocatalysts offers a unique opportunity for the full use of solar energy to solve the energy and the environmental problems. Here, successful preparation of a three-dimensional (3D) porous photocatalyst of graphitic carbon nitride quantum dot (CNQDs) modified g-C 3 N 4 /graphene oxide composite aerogel (CNGO/CNQDs) via hydrothermal and vacuum injection method was reported. In this unique ternary 3D photocatalyst, graphene oxide could improve the separation of photogenerated electrons and holes and promote the charge separation, while the aerogel's 3D network structure provided a rich active site. Simultaneously, due to the appropriate up-conversion performance of the nitrogen carbide quantum dots, CNGO/CNQDs achieved a light response from ultraviolet (UV) to near-infrared (NIR). These properties endow it with a good photocatalytic performance. The hydrogen production efficiency of CNGO/CNQDs reached 1231 μmol h −1 , which was 16 times more than that of matrix material . In addition, the apparent quantum yields (AQY) of CNGO/CNQDs at wavelengths of 420 nm and 700 nm were 13% and 0.116%, respectively.
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高影响因子
ACS Applied Materials & Interfaces
·
2019
·
IF 8.456
Lunlun Gong,Heng Yin,Chengming Nie,Xuran Sun,Xiuli Wang,Mei Wang
Although hybrid photocathodes built by immobilizing molecular catalysts to the surface of semiconductors through chemical linkages have been reported in recent years, systematic and comparative studies remain scarce about the impact of various anchoring groups on the performance, stability, and charge-transfer kinetics of molecular catalyst-decorated hybrid photocathodes for photoelectrochemical (PEC) H2 production. In this study, the molecular cobaloxime catalysts, CoPy-4-X (Py = pyridine, X = PO3H2, COOH, and CONH(OH)), bearing different anchoring groups were synthesized and covalently immobilized to the surface of the porous TiO2 layer coated on a p-Si plate or a fluorine-doped tin oxide glass. The influence of the anchoring groups on the performance of p-Si/TiO2/CoPy-4-X photocathodes was comparatively studied for PEC H2 evolution. Among the tested hybrid photocathodes, the one with a hydroxamate as an anchoring group displayed higher activity and lower charge-transfer resistance than that observed for the electrode with a carboxylate or a phosphonate as the anchoring group. Notably, the catalytic current of p-Si/TiO2/CoPy-4-CONH(OH) was attenuated only by 2.9% in the controlled potential photoelectrolysis tests in borate buffer solution at pH 9 at 0 V versus a reversible hydrogen electrode over 6 h. Moreover, the influence of anchoring groups on the interfacial electron transfer from the TiO2 layer to the immobilized cobaloxime catalyst and electron–hole recombination was studied by transient absorption spectroscopy. These results revealed that the hydroxamate as an anchoring group is superior to the carboxylate and phosphonate groups for speeding up the interfacial electron transfer and firmly immobilizing the molecular catalysts to the metal oxide semiconductors to build efficient and stable hybrid photoelectrodes.
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PubMed
高影响因子
Journal of Materials Chemistry A
·
2015
·Vol. 3
·期 47
·23732-23742
·
IF 7.443
Li Zhang,Xianliang Fu,Sugang Meng,Xiaoliang Jiang,Jinghui Wang,Shifu Chen
Noble metal-modified CdS is one of the most promising photocatalysts for solar H2 production due to its intrinsic band structure merits. It is highly desirable to develop an effective preparation route to pursue a high photocatalytic performance and to minimize the use of costly noble metals. For the first time, a simple and convenient one-pot solvothermal (OPS) method was developed to prepare platinized CdS nanorods (Pt/CdS-N) in this work. The formation of a hexagonal 1D structure CdS and the deposition of Pt(0) can be achieved simultaneously by the method, which is more efficient than the conventional post-deposition routes, such as photochemical reduction and impregnation–reduction methods, to enhance the photocatalytic activity of CdS-N for the H2 evolution reaction (HER). The H2 evolution rate (rH2) of CdS-N could be remarkably improved from 2.10 to 10.29 mmol h−1 g−1 by loading with only 0.06% Pt (wt%) under visible light irradiation (λ > 400 nm, 300 W Xe lamp). No deactivation of the sample was observed in cyclic experiments for 20 h reaction. This loading amount of Pt is substantially lower than the reported optimal values (commonly in the range of 0.5–2%) by more than one order of magnitude. A criterion of enhancement coefficient was proposed to identify the ideal loading amount of Pt. The result indicates that, considering the improvement efficiency of rH2 and the loading amount of Pt, this ultra-low amount of Pt is more practical than the optimal amount (determined to be 0.5%). The high and stable activity of Pt/CdS-N can be attributed to the hexagonal 1D structure of CdS and the high dispersion of Pt in the Pt(0) state. Besides Pt, the OPS method is also valid for the deposition of Pd or Ru on CdS and rH2 decreases in the order Ru/CdS-N (12.89) > Pt/CdS-N (10.29) > Pd/CdS-N (6.72 mmol h−1 g−1) with a loading amount of 0.06%. It reveals that the use of noble metal co-catalysts can be significantly reduced without unduly sacrificing the HRE efficiency. The developed OPS route provides a new insight into the preparation of highly efficient and stable chalcogenide photocatalysts for the HER.
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高影响因子
Catalysis Science & Technology
·
2014
·Vol. 5
·期 1
·405-414
·
IF 4.76
Hongmei Liu,Kai Tao,Chunrong Xiong,Shenghu Zhou
In this work, Pd–NiO@SiO2 core–shell mesoporous nanocatalysts with ~4 nm Pd–NiO heteroaggregate nanoparticle cores and ~17 nm mesoporous silica shells were successfully synthesized by a sol–gel method. The surfactant-capped PdNi alloy nanoparticles were coated with SiO2 through hydrolysis of tetraethylorthosilicate to obtain PdNi@SiO2 nanoparticles, and the mesoporous Pd–NiO@SiO2 core–shell nanocatalysts were formed after removal of surfactants by calcination at 500 °C and subsequent H2 reduction at 200 °C. The characterization results by XRD, TEM and BET revealed that Pd–NiO@SiO2 nanocatalysts were highly stable with the maintenance of intact core–shell structures under high-temperature thermal treatments. The Pd–NiO@SiO2 nanocatalysts illustrated a superior catalytic performance for p-chloronitrobenzene hydrogenation with H2 to the control Pd@SiO2 nanocatalysts. The catalytic performance enhancement of Pd–NiO@SiO2 nanocatalysts is ascribed to the strong interaction between Pd and NiO in the cores, where the interfaces may be beneficial for hydrogenation reactions.
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高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2015
·
IF 3.313
Yuanchen Hong,Penghui Shi,Peifu Wang,Weifeng Yao
CdS were synthesised in situ on graphene oxide (GO) using a simple solvothermal method . GO in the prepared powders was then photoreduced into RGO to form the CdS/GO composites. The samples were characterised by using the X-ray diffraction spectra (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), fluorescence spectrum and Raman spectrum . The prepared CdS/RGO exhibited much higher activity for H 2 evolution than CdS or CdS mechanically loaded with GO under visible light irradiation (>420 nm). The improved photocatalyst performance of CdS/RGO was attributed to enhancement of the connection between CdS and RGO sheets, which accelerates the effect of the separation of photoinduced electrons and holes by transferring the photoinduced electron to RGO sheets.
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高影响因子
APPLIED SURFACE SCIENCE
·
2017
·
IF 3.387
Fei Ye,Houfen Li,Hongtao Yu,Shuo Chen,Xie Quan
Protons tend to bond strongly with unsaturated-coordinate S element located at the edge of nano-MoS 2 and are consequently reduced to H 2 . Therefore, increasing the active S atoms quantity will be a feasible approach to enhance hydrogen evolution. Herein we developed a porous TiO 2 derived from metal organic frameworks (MOFs) as scaffold to restrict the growth and inhibit the aggregation of MoS 2 nanosheets. As a result, the thickness of the prepared MoS 2 nanosheets was less than 3 nm (1–4 layers), with more edges and active S atoms being exposed. This few-layer MoS 2 -porous TiO 2 exhibits a H 2 evolution rate of 897.5 μmol h −1 g −1 , which is nearly twice as much as free-stand MoS 2 nanosheets and twenty times more than physical mixture of MoS 2 with porous TiO 2 . The high performance is attributed to that more active edge sites in few-layer MoS 2 -porous TiO 2 are exposed than pure MoS 2. This work provides a new method to construct MOFs derived porous structures for controlling MoS 2 to expose active sites for HER.
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高影响因子
RSC Advances
·
2016
·Vol. 6
·期 107
·105338-105346
·
IF 3.289
Deyuan Xie,Ye Sun,Tianle Zhu,Xing Fan,Xiaowei Hong,Wenhao Yang
NH3 synthesis from H2O + N2, H2 + N2 or H2O + H2 + N2 by dielectric barrier discharge combined with an Ru/Al2O3 catalyst is studied at atmospheric pressure and room temperature. Additionally, the effects of reaction gas composition, energy density, and discharge frequency on NH3 yield and by-product formation are investigated. The results show that NH3 can be formed from reaction gases consisting of H2O and N2. The NH3 yield of the reaction gas containing H2 is much higher than that of the reaction gas consisting of H2O and N2. The presence of H2O has a promotion effect on NH3 synthesis from H2 and N2, especially for reaction gases with an H2 content less than 10%. The NH3 yield first increases and then decreases with an increase in the energy density. The maximum yield of 680 mg kW−1 h−1 occurs at the energy density of 1400 J L−1 and in the reaction gas of 0.14% H2O, 40% H2 and N2. The discharge frequency has a great effect on the NH3 yield, and maximum NH3 yield is obtained at the frequency of 13 kHz. Besides NH3, some by-products, such as N2O and NO2, are also formed with reaction gases containing H2O. However, their formation can be suppressed in the presence of H2, which is attributed to the reduction effect of H2 on the by-products.
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高影响因子
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