INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2023
·
IF 7.2
Qi Sui,Runjie Li,Yanyan Zhang,Mengtian Huang,Ting Wang,Man Yang,Miao Cao,Xiaoping Hong,Benxia Li
Accelerating the charge transfer (CT) capability of photocatalysts is an efficient way to improve the overall photocatalytic performance, yet the precise regulation of CT in photocatalyst systems is still lacking. In this paper, a series of hybrid photocatalysts composed of graphitic carbon nitride ( CN ) and various viologens ( V ) were prepared for the photocatalytic hydrogen evolution (PHE) from water splitting under visible-light irradiation. Considering the fixed energy structure of CN , the different electron-withdrawing substituents were introduced to engineer the band structure of V delicately and modulate the CT process between CN and V . It was shown that all the hybrid photocatalysts CN-x%V y exhibited higher photocatalytic performance, of which CN–1%V 3 , possessing the strongest electron withdrawing group (-NO 2 ), demonstrated the best PHE performance (3572.3 μmol g −1 h −1 ), exceeding 29 times over the unmodified CN . It was proposed that the introduction of V can optimize the interfacial photogenerated electron transfer ( CN → V →Pt) of the whole photocatalytic system effectively. We highlighted the V as an efficient chemical segment to modify semiconductors toward enhanced activity due to the following unique characteristics: (i) the unique redox ability, (ii) the easy synthetic methods for controlling the band structures precisely, and (iii) the inherent positively charged feature. This work provides a deep understanding of CT for the rational design of high-performance photocatalysts through band engineering.
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JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
·
2022
·
IF 10.319
Long Sun,Lingling Li,Jiajie Fan,Quanlong Xu,Dekun Ma
The rapid charge recombination and low surface reaction kinetics are the two major constraints to the photocatalytic performance of covalent organic frameworks (COFs). To accelerate the charge separation behavior, TpPa-1-COF is decorated with WO 3 via an in-situ growth approach, and the resultant WO 3 /TpPa-1-COF composites show significantly improved photocatalytic performance. Especially, when the WO 3 loading arrives at 3 wt%, 3%WO 3 /TpPa-1-COF exhibits the maximum photocatalytic H 2 evolution rate of 19.89 mmol g −1 h −1 , which is approximately 4.8 times higher than that of pure TpPa-1-COF. The apparent quantum efficiency (AQE) of 3%WO 3 /TpPa-1-COF at 420 nm is detected to be 12.4%. X-ray photoelectron spectroscopy (XPS) characterization confirms the formation of internal electric field between WO 3 and TpPa-1-CF, which can drive the photogenerated charge carrier diffusion in S-scheme mode. As a result, WO 3 /TpPa-1-COF composite possesses high charge separation efficiency and strong redox ability, which is further supported by the photoelectrochemical results, thus benefiting the photocatalysis process. This work provides a rational strategy to modify COFs in photocatalytic water splitting.
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ChemSusChem
·
2022
·Vol. 15
·期 8
·e202200063
·
IF 9.14
Qing Ji,Xiaoping Chen,Ya-Jun Cheng,Qingyu Dong,Yanbin Shen,Zhaohui Yang,Binjie Hu,Yonggao Xia
Graphical Carbon, the master : Constructed with unique carbon emcoating structure through CO 2 acivation, NbO 2 benefited from an effective and highly conductive carbon network, giving rise to exceptional electrochemical performances in terms of reversible capacities, rate capability, and cyclic stability. As a promising alternative as lithium-ion anode, niobium dioxide appeals to researchers due to high theoretical capacity and good electron conductivity. However, rarely work about NbO 2 based high performance anode is reported. Here, NbO 2 nanoparticles emcoated in continuous carbon matrix is constructed through CO 2 /H 2 coupling treatment. CO 2 activation introduces unique carbon emcoating structure, which builds interconnected electron conductive network with low carbon content. Furthermore, crystallographic phase of NbO 2 is enhanced during H 2 treatment, which increases the lithium storage ability. Electrochemical performance of NbO 2 anodes is significantly improved based on the carbon emcoating structure. A high reversible capacity of 391 mAh g −1 is retained after 350 cycles at 0.2 C. Additionally, at a current density of 1 A g −1 , the reversible capacity reaches 139 mAh g −1 . Compared with conventional NbO 2 /C nanohybrids, the lithium diffusion coefficient of carbon-emcoated sample shows improvement of three orders of magnitude. Moreover, the in situ XRD investigation shows a reversible lithium insertion behaviour with a limited volume change.
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高影响因子
FUEL
·
2022
·
IF 8.035
Haoyu Huang,Xin Hu,Zhuoran Hou,Di Yang,Dan Xiang,Liwen Hu
The hydrogen is described as a clean and sustainable alternative to fossil fuels in numerous energy systems. Hydrolysis is an important method for high purity, high volume hydrogen production. In order to accelerate the kinetics of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline media, it is essential to explore efficient catalysts. In this paper, the nanoscale self-supported Mn-NiS/Mn-Ni 3 S 4 composite catalysts was assembled on nickel foam. Benefiting from the lattice distortion and vacancy defects caused by the doping of Mn elements, the catalysts exposed an increasing number of electrochemical surfaces and effective active sites, showing impressive electrochemical performance with a HER overpotential of only 94.2 mV at 10 mA/cm 2 and an OER overpotential of only 253 mV to drive 50 mA/cm 2 . Applying as the bifunctional catalysts, the Mn-NiS/Mn-Ni 3 S 4 couple only achieved a low voltage of only 1.52 V to drive 10 mA/cm 2 . This paper provides new ideas and references for the rational design of high-performance sulfide catalysts with non-precious metal composites.
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Materials Today Communications
·
2022
·
IF 3.662
Zicheng He,Yunjie Lin,Mingfu Ye,Wenqing Zhu,Guochang Chen
The bismuth-containing semiconductors have emerged as promising materials for the degradation of organic pollutants and reduction of CO 2 . However, their potential applications in photocatalytic H 2 generation have not been explored clearly. Herein, bismuth-containing multicomponent photocatalyst Ag-BWV-y (where y represents the moles of Ag + in the initial reaction system) has been synthesized by a simple one-pot chemical method for photocatalytic H 2 generation. The element Ag is homogeneously distributed in as-prepared nanocomposite, and the band structure of Ag-BWV-y can be tuned by the dosage of Ag + ions. The optimized photocatalyst Ag-BWV-y (y = 0.15) shows a maximum H 2 evolution rate of 652 μmol h −1 g −1 , which is about 5.6-fold that of undoped sample. The narrow band gap of Ag-BVW-0.15 favors the photocatalytic activity in promoting H 2 production.
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FUEL
·
2022
·
IF 8.035
Fuhua Xu,Yanlan Wang,Changlong Wang,Wenkai Huang,Xiang Liu
In despite of significant progresses have been accomplished in the programming and development of updated and efficient nana-catalysts for H 2 production from a wide variety of chemical hydrogen storage materials. However, it is a practical matter of the utmost importance to develop the “on-off” control for on demand H 2 release in the cause of effectively and safely producing, carrying and depositing H 2 gas. Herein, we have first designed and synthesized a sequence of carbon nanosphere (CNS)-stabilized bimetallic PtNi nanoparticles (PtNi/CNS), by stabilization of nearly monodispersed PtNi bimetallic nanoparticles onto the surface of carbon nanosphere, for the highly selective and efficient on-demand H 2 release upon the dehydrogenation of hydrous hydrazine. Then, the optional nanocatalyst Pt 1 Ni 1 /CNS exhibits the highest catalytic performance in hydrogen production from dehydrogenation of hydrous hydrazine, with 100 % H 2 selectivity and the turnover frequency (TOF) of 3928 mol (H 2 )·mol cat −1 ·h −1 at 50 °C. The detailed physical characterizations have confirmed that the superior catalytic performance of Pt 1 Ni 1 /CNS in the H 2 release upon hydrous hydrazine dehydrogenation is attributed to the electronic interaction and synergistic effect between Ni and Pt. More importantly, the highly selective “on-off” control for demand-based H 2 release upon the dehydrogenation of hydrous hydrazine is successfully realized by pH regulation.
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Materials Today Energy
·
2022
·
IF 9.257
Guanyu Wu,Zhao Mo,Peipei Sun,Zhuocheng Cao,Xianglin Zhu,Yanhua Song,Yuechang Wei,Xiaojie She,Huaming Li,Hui Xu
Photocatalytic hydrogen evolution reaction (HER) using solar energy as a driving force is considered to be one of the most promising approaches to alleviate energy and environmental problems. However, the problem of low solar conversion efficiency resulted from the easy recombination of photogenerated electron-hole pairs in semiconductor catalysts needs to be solved urgently. Theoretical calculations were firstly taken to prove that copper nitride (Cu 3 N) exhibits a matched D-band center position and hydrogen adsorption Gibbs free energy (ΔG H∗ ), which can improve the H 2 adsorption/desorption balance and then achieve an effective promotion of photogenerated charge kinetics. Cu 3 N was herein chosen as a co-catalyst to enhance photocatalytic HER performance. Two-dimensional carbon nitride (2D CN) was chosen as the catalyst due to the layer structure which could shorten electronic transmission distance. The results showed that the HER activity of Cu 3 N/2D CN is 117 times higher than that of 2D CN (2721.55 vs. 23.18 μmol/g/h) and an apparent quantum yield of 3.78% at 420 nm. Compared with other Cu(I)-based composite catalysts, Cu 3 N/2D CN also exhibits the highest HER activity. This work investigates the transfer process of photogenerated carriers and reveals the photocatalytic mechanism through a combination of theoretical calculations and experimental characterization.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2022
·
IF 7.139
Fengzhi Wang,Jiaqi Hu,Rong Liang,Weisheng Lei,Zirui Lou,Xinhua Pan,Bin Lu,Zhizhen Ye
Binary heterostructures (named as CN@Re) composed of ReS 2 nanospheres and g-C 3 N 4 nanosheets are constructed by electrostatic self-assembly method. The ReS 2 nanospheres were prepared by hydrothermal method and the g-C 3 N 4 nanosheets were treated with surface charge modification. Hydrogen production efficiency of modified CN and CN@Re nanostructures was evaluated in a simulated solar environment. To our surprise, CN5@Re5% exhibits the highest H 2 production up to 1823 μmol g −1 h −1 of CN5@Rey, which is 3.2 times as high as CN. The improvement of the photocatalytic hydrogen production efficiency of modified CN is attributed to its interaction with the hole sacrificing agent lactic acid, while the improvement of the photocatalytic activity of CN@Re nanostructure is attributed to the efficient electron transfer efficiency between CN and ReS 2 and the enhanced light absorption capacity brought by ReS 2 . In addition, the photocatalytic stability of CN5@Re5% has been studied, which can maintain a stable rate of hydrogen production over four cycles. The apparent quantum efficiency is as high as 4.10% at 365 nm and 2.82% at 420 nm.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2022
·
IF 7.139
Qiongqiong Wang,Yaxi Tian,Mengyun Chen,Rongfeng Guan,Haibin Yuan
Photocatalytic production H 2 of splitting water is an important branch of the application of photocatalytic materials. In this paper, porous C doped carbon nitride was successfully synthesized by calcining urea and acetamide at high temperature, and then analyzed by various characterization methods. XRD and FT-IR spectra show that the crystal structure of carbon nitride modified by acetamide are similar to bulk carbon nitride. SEM and TEM spectra show that the morphology and structure of carbon nitride and carbon nitride was modified by acetamide, which presents a porous nanosheets structure. XPS and EDS show that the content of carbon element in carbon nitride modified by acetamide increased significantly. The PL spectrum is obviously red shift, and the light absorption range is obviously enlarged, which is consistent with the absorption edge of UV–vis Spectrum. The BET of the optimized sample CN2-6 is 122.79 m 2 g -1 , which is 3.04 times higher than that of bulk carbon nitride CN1 (40.456 m 2 g -1 ). In addition, the hydrogen production of CN2-6 is 13169.04 μmol/g/h under 300 W Xenon lamp, which is 14.95 times more than CN1 (880.82 μmol/g/h) hydrogen production rate. When the light source is a 10 W LED lamp , the apparent quantum efficiency (AQE) of sample CN2-6 reaches the maximum (2.91) under the wavelengths of 430 nm, which is 1.27 times more than CN1 under the same conditions. Meanwhile, prepared samples have excellent stability and durability under visible light.
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Nanomaterials
·
2021
·Vol. 11
·期 6
·1480
·
IF 5.076
Weinan Xing,Ke Cheng,Yichi Zhang,Jie Ran,Guangyu Wu
The incorporation of nonmetal group dopants into a graphitic carbon nitride (g-C3N4) framework is fabricated by adding a small amount of hexamethylenetetramine during the thermal polymerization process. The material shows an excellent visible-light photocatalytic H2production performance that is eight times higher than bulk g-C3N4. This outstanding performance is ascribed to the introducing of N-doped carbon, which not only enhances the light absorption and favorsa narrower band gap, but also upshifts the conductionband (CB) potential, resulting in a better reduction ability of electrons. This discovery has potential significancefor the designing of high performance, economic, and environmental friendly photocatalyst for solar energy conversion.Keywords:g-C3N4;nonmetal group dopants;photocatalytic hydrogen production;semiconductors;energy storage and conversion
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高影响因子
Journal of Materials Chemistry A
·
2021
·Vol. 9
·期 35
·19984-19993
·
IF 12.732
Hao Wang,Peng Hu,Jie Zhou,Maarten B. J. Roeffaers,Bo Weng,Yongqing Wang,Hongbing Ji
Ultrathin 2D/2D Ti3C2Tx/semiconductor (CdS and Bi2MoO6) dual-functional photocatalysts have been constructed for the oxidative coupling of benzylamines to imines combined with H2 generation under visible light irradiation (λ ≥420 nm). The optimal 2D/2D Ti3C2Tx/CdS sample exhibits high photocatalytic performance toward H2 evolution (219.7 μmol g−1 h−1) and imine production (155.8 μmol g−1 h−1), which is 5 times and 6 times higher than that of pure CdS, respectively. In situ irradiated XPS and photoelectrochemical characterizations reveal that the enhanced photoactivity over Ti3C2Tx/semiconductor heterostructures can be attributed to the facilitated charge separation from the semiconductors to the Ti3C2Tx cocatalyst. A possible reaction mechanism is proposed based on in situ FTIR spectroscopy of benzylamine adsorption and imine product desorption and reaction intermediate detection using in situ ESR. This work provides a systematic strategy to construct ultrathin 2D/2D Ti3C2Tx/semiconductor heterojunctions for photocatalytic synthesis of high value-added products combined with H2 generation.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2021
·
IF 5.816
Xiaoxiao Chen,Mengyao Liu,Lijuan Zhang,Yunshan Zhou,Enming Ping,Chunyan Ding
ZIF-67@NH 2 –SiO 2 composites were prepared by loading the metal-organic frameworks ZIF-67 on amino modified SiO 2 gel particles (NH 2 –SiO 2 , 80–100 mesh) through layer-by-layer self-assembly method. Systematic investigation on the effects of ZIF-67 loading amounts on NH 2 –SiO 2 packed stainless steel chromatographic column (specification 1.0 m×2.0 mm I.D.), the flow rate of He as carrier gas and the injection amount of mixed gas (H 2 /D 2 ) on the hydrogen isotope H 2 /D 2 separation performance at liquid nitrogen temperature, unraveled the optimal conditions for H 2 /D 2 isotope separation . The results showed that the optimal stationary phase materials under the optimized conditions can effectively separate H 2 and D 2 with separation resolution R = 1.52 and the separation time t = 10.15 min. The superior performance of the ZIF-67 is tentatively thought to be due to kinetic quantum sieving (pore size 3.3 Å) effect and chemical affinity sieving effect of Co ion in ZIF-67.
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