CHEMICAL ENGINEERING JOURNAL
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2023
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IF 15.1
Weiwei Yang,Mao Peng,Ye Lv,Mengya Sun,Jinli Zhang,Wei Li,Yan Fu
2-Hydroxybenzaldehyde (SALD) exhibits special reactivity in various chemical reactions due to the existence of aldehyde and hydroxyl groups, which also make it a challenge to achieve high conversion and selectivity for SALD production. Herein, β-Ni(OH) 2 nanosheets over nickel foam (NF) at different hydrothermal temperatures were synthesized for electrocatalytic oxidation (ECO) of 2-hydroxybenzyl alcohol (SAL) into SALD. The β-Ni(OH) 2 electrode obtained at 160 °C achieves the best ECO performance in 2.5 M KOH at the applied potential of 1.45 V (RHE), showing the SALD selectivity of 78.90% and the Faradaic efficiency of 87.94% at the SAL conversion of 69.76%. ECO of SAL reduces the cell voltage and boosts the hydrogen productivity by 2.74 times. It is of great importance to find that potential-driven surface reconstruction of β-Ni(OH) 2 enables selective conversion of SAL into SALD. Side reactions including OER as well as oxidation of phenolic group can be effectively controlled via regulating applied potentials on β-Ni(OH) 2 . This work is the first report on direct electrochemical oxidation of SAL with high SALD selectivity, and offers a green and clean strategy for highly selective production of SALD under mild conditions.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2023
·
IF 9.9
Bing Xing,Ting Wang,Xiaobo Han,Kun Zhang,Benxia Li
The rational integration of semiconductor quantum dots (QDs) with anatase TiO 2 nanostructures is a promising strategy to develop efficient photocatalysts. Herein, Bi 2 S 3 QD/TiO 2 photocatalyst was constructed by controllably depositing Bi 2 S 3 QDs on flower-like TiO 2 nanostructures and used for the photocatalytic redox-coupling reaction of H 2 evolution and oxidative transformation of benzyl alcohol. The abundant amino groups in TiO 2 nanostructures served as the anchoring sites for uniform growth of Bi 2 S 3 QDs. The anchoring of Bi 2 S 3 QDs onto TiO 2 nanostructures not only enhanced the photoabsorption ability and the photogenerated charge separation efficiency but also afforded powerful photogenerated charge carriers and abundant active sites for the photocatalytic reaction. As a result, the Bi 2 S 3 QD/TiO 2 photocatalyst exhibited a favorable performance in the redox-coupling reaction, providing the high production rates of H 2 up to 4.75 mmol·g cat −1 ·h −1 and benzaldehyde up to 6.12 mmol·g cat −1 ·h −1 , respectively, as well as an excellent stability in the long-term photocatalytic reaction. Meanwhile, a trace amount of water in the reaction system could act as a promoter to accelerate the photocatalytic redox-coupling reaction. The photocatalytic mechanism following S-scheme heterojunction was proposed according to the systematic characterizations and experimental results. This work offers some insight into the rational construction of efficient and cost-effective photocatalysts for the conversion of solar to chemical energy.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2023
·
IF 9.9
Xiaoli Jin,Huiqing Wang,Xiongtao Lv,Qing Lan,Teng Ge,Lin Guo,Xin Li,Hongxian Sun,Chenghua Ding,Yuwei Guo,Haiquan Xie,Liqun Ye
The development of bifunctional photocatalysts for enhancing hydrogen (H 2 ) and hydrogen peroxide (H 2 O 2 ) production from water is essential in addressing environmental and energy issues. However, the practical implementation of photocatalytic technology is still constrained by the inadequate separation of photo-generated charge carriers. Herein, potassium (K) atoms are introduced into the interlayers of graphitic carbon nitride (g-C 3 N 4 ) with a hollow hexagonal structure (K-TCN) and are coordinated with N atoms in adjacent layers. The presence of K–N coordination serves as a layer bridge, facilitating the separation of charge carriers. The hollow hexagonal structure reduces the distance over which photogenerated electrons migrate to the surface, thereby enhancing the reaction kinetics. Consequently, the optimized K-TCN exhibits a dramatically improved photocatalytic H 2 (941.6 μmol g −1 h −1 with platinum (Pt) as the cocatalyst) and H 2 O 2 (347.6 μmol g −1 h −1 ) generation as compared to hollow g-C 3 N 4 (TCN) and bulk g-C 3 N 4 nanosheet (CN) without K–N bridge under visible light irradiation. The unique design holds promising potential for developing highly efficient bifunctional photocatalysts towards producing renewable fuels and value-added chemicals.
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CHEMICAL ENGINEERING SCIENCE
·
2023
·
IF 4.7
Jiale Wu,Yuan Tao,Dang Cheng,Fener Chen
Herein, we demonstrate a hybrid microflow system consisting of a coaxial double-tube microreactor and a capillary microreactor for performing borohydride reduction of α , β -unsaturated esters to allylic alcohols in a highly controlled and safe manner. Using methyl cinnamate as the model substrate and LiBH 4 as reductant, complete conversion was achieved in 75 s residence time at 80 ℃ with up to 85% yield of the target product cinnamyl alcohol under optimized conditions in the hybrid microflow system, enabling selective borohydride reduction of α , β -unsaturated esters to allylic alcohols without the need of using metallic salts as additives or co-reagents. The kinetics of this reduction reaction has been examined and modelled, providing an understanding of the intensified reaction behaviour and the reaction performance of the hybrid microflow process. The results presented can shed new light on the development of continuous microflow processes for the hydridic type of reductions.
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CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Mingrui Guo,Meng Chen,Jixiang Xu,Chao Wang,Lei Wang
Introducing defects and heteroatoms on carbon nitride (g-C 3 N 4 , CN) framework are effective ways to enhance its photocatalytic activity by regulating light absorption and charge carriers separation. Herein, a mechanochemical method was employed to synthesize Br-doped C, N-deficient CN (CN V -mCN-Br) via ball-milling of N-containing precursor and 6-Bromopyridine-3-carbaldehyde (BrPyCHO) followed by calcining. The ball-milling-evolved mechanical forces and BrPyCHO-derived HBr induced formation of C, N vacancies and C-Br bond in CN V -mCN-Br framework. The CN V -mCN-Br exhibited curled nanosheets morphology and separated electrons-holes distribution. The photocatalytic H 2 evolution rates of 1 %Pt-loaded CN V -mCN-Br in distilled water and simulated seawater were 22.21 and 34.41 mmol g –1 h −1 , respectively with 10% triethanolamine . The corresponding apparent quantum yields were 25.87% and 40.08% at 420 nm. This work provides a facile technique to simultaneously introduce defect and heteroatom in CN for high-efficiency photocatalytic H 2 evolution.
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CHEMICAL ENGINEERING JOURNAL
·
2019
·
IF 8.355
Zimo Lou,Jiang Xu,Jiasheng Zhou,Kunlun Yang,Zhen Cao,Yizhou Li,Yuanli Liu,Liping Lou,Xinhua Xu
Atomic H* has been regarded as the key active species for the electrocatalytic hydrodechlorination (ECH), and the electrode design and operation conditions are related to the atomic H* generation. However, there is limited understanding of how the operation parameters affect the atomic H* generation and utilization. Due to the fact that Pd was inefficient in water dissociation step, MnO 2 was combined with Pd to construct a novel Pd/MnO 2 /Ni foam cathode. Cyclic voltammetry confirmed that Pd/MnO 2 /Ni foam cathode with MnO 2 load of 0.51 mg cm −2 possessed the highest atomic H* generation and ECH activity. Excessive Pd load (>0.44 mg cm −2 ) was detrimental to ECH because of the side hydrogen evolution reaction (HER). Operation conditions (e.g. applied current and electrolyte concentration) would directly affect the cathode potential, which was an important indicator of the atomic H* generation. The optimal cathode potential was determined to be −0.85 V when the applied current was 10 mA in this study. The electrolyte concentration of 10–15 mM was able to provide sufficient atomic H* for ECH, while excessive input of electrolyte would favor HER but inhibit ECH. ECH at acidic and neutral/alkaline solution underwent different pathways for atomic H* generation and further affect the utilization of atomic H*. After 120 min reaction, >70% of atomic H* could be selectively used for ECH at initial pH of 4.0 and 5.0, while only ∼37% was used for ECH at initial pH of 7.0. This work correlated the reactivity of electrode with the atomic H* and cathode potential, which would provide strategies for ECH catalyst design and operation optimization.
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Chemistry-An Asian Journal
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2018
·Vol. 14
·期 3
·416-421
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IF 3.692
Qian Wang,Wei Sun,Tianying Xie,Limei Cao,Ji Yang
Graphical Carbon-coated catalysts : Octahedral Pt/ZrO 2 @C, prepared by direct carbonization of the precursor UiO-66-NH 2 (a zirconium-based metal–organic framework), exhibits improved catalytic activity for selective catalytic reduction with H 2 at ambient temperature, compared with that of other platinum-based catalysts with porous materials as supports (see figure). Selective catalytic reduction (SCR) of NO x with H 2 as a reductant is the most promising denitration technology at low temperature. Achieving the conversion of NO x into N 2 at ambient temperature not only prolongs the service life of the catalyst, but also provides more freedom for the arrangement of denitration units throughout the flue gas treatment equipment. However, the development of highly efficient, stable, and environmentally benign supported platinum-based catalysts for H 2 -SCR at ambient temperature is still a major challenge. Herein, a 0.5 wt % Pt/ZrO 2 @C catalyst, which was composed of carbon-coated octahedral ZrO 2 with highly dispersed Pt particles, was prepared by using a new stabilization strategy based on UiO-66-NH 2 (a zirconium metal–organic framework) as a template. The catalytic performance of this Pt/ZrO 2 @C in H 2 -SCR was tested and confirmed to achieve near 100 % NO x conversion at 90 °C. Also, 70 % N 2 selectivity of the catalyst was achieved. The morphology, structure, and porous properties of the as-synthesized nanocomposites were characterized by using data obtained from field-emission SEM, TEM, XRD, Raman spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, and N 2 adsorption–desorption isotherms. The results show that residual carbon formed by pyrolysis treatment is coated on octahedral ZrO 2 , and effectively prevents the agglomeration of platinum particles on the surface.
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Journal of Materials Chemistry A
·
2019
·Vol. 7
·期 10
·5324-5332
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IF 10.733
Mao Wu,Yansheng Gong,Tao Nie,Jin Zhang,Rui Wang,Huanwen Wang,Beibei He
Nanocage-like 3D porous graphitic carbon nitride (g-C3N4) with a high surface area and nitrogen defects was successfully prepared via a novel, template-free, cost-effective and hydrothermal-copolymerization route. Compared with pristine g-C3N4, the synergetic effect of nitrogen vacancies combined with a nanocage-like structure endowed it with a broad visible-light-responsive range, more exposed active lateral edges and catalytically active sites, as well as efficient separation of photogenerated carriers. As a consequence, the modified g-C3N4 exhibited prominent photocatalytic performance in water splitting for the hydrogen evolution reaction under visible light illumination. The optimized photocatalyst (DCN-550) showed a maximum photocatalytic H2 evolution rate of 92.57 μmol h−1, almost 20.3 times higher than that of pristine g-C3N4. Moreover, a possible mechanism for the photocatalytic hydrogen evolution and nanostructure formation process based on the experimental results was proposed. The new growth strategy developed here could inspire similar attempts to modify novel visible-light-driven photocatalysts through nanostructure design.
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Energy Technology
·
2018
·Vol. 7
·期 8
·1800846
·
IF 3.175
Sibo Chen,Siyuan Yang,Xiaolin Sun,Kelin He,Yun Hau Ng,Xin Cai,Wuyi Zhou,Yueping Fang,Shengsen Zhang
The photocatalytic H 2 evolution is an important technology to solve the energy crisis. The hydrogen evolution rate of the graphite carbon nitride (g-C 3 N 4 ) system in triethanolamine solution as sacrificial agent is clearly higher than that in methanol solution. But up to now, most of the Cu nanoparticles as cocatalyst of g-C 3 N 4 photocatalytic systems for hydrogen evolution are performed in methanol solution because Cu nanoparticles are unstable in triethanolamine solution. Here, carbon-coated Cu nanoparticles as a cocatalyst of g-C 3 N 4 composites (Cu@C/g-C 3 N 4 ) are prepared by a simple two-step technology that includes annealing followed by grinding. The compositions, morphology, and optical and photoelectrochemical properties of the composites are characterized by means of physicochemical techniques. The prepared composition is used to generate hydrogen under visible-light irradiation in triethanolamine solution. The results show that the hydrogen evolution rate of the optimal Cu@C/g-C 3 N 4 is up to 265.1 μmol g −1 h −1 , which is close to the activity of 0.5% Pt/g-C 3 N 4 , and after four repeated reactions, the photocatalytic activity decreases only by ≈15%. The good photocatalytic activity and stability result from Cu nanoparticles increase the transfer efficiency of charge carriers by trapping the photogenerated electrons produced by g-C 3 N 4 and the protective effect of carbon layer on Cu nanoparticles.
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Journal of Physical Chemistry C
·
2018
·
IF 4.484
Chengzhang Zhu,Xiao Chen,Jian Ma,Cheng Gu,Qiming Xian,Tingting Gong,Cheng Sun
Inducing TiO2 sensitive to visible light and effectively restraining the possibility of electron–hole recombination are crucial for actual applications over TiO2-based catalysts. In this study, a facile strategy to fabricate three-dimensional (3D) defective TiO2–x@carbon spheres (CSs) composite modified with two-dimensional (2D) graphite-like carbon nitride (g-C3N4) nanosheets (NSs) is presented. During the synthesis process, zero-dimensional tiny TiO2–x nanoparticles were evenly loaded onto CSs with intimate chemically bonded (Ti–O–C) interfaces. Simultaneously, loose g-C3N4 NSs were tightly coated on the hierarchical spherelike TiO2–x@CSs, with the purpose of supporting an effectively protective layer to prevent the oxidation of the directly exposed Ti3+ and constructing highly efficient 2D/3D ternary heterostructures with strong interfacial interaction. The obtained CSs/TiO2–x@g-C3N4 heterojunction showed remarkably enhanced photocatalytic activity in hydrogen production and toxic pollutants degradation compared to the binary composites or pristine components, mainly due to the cooperative effects of the enhanced visible-light-harvesting capacity introduced by Ti3+ and CSs, effective interfacial charge separation (Ti–O–C structure and heterostructure), and the vectorial charge-transfer channel design. This work paves a green, gentle, and economical way to design more efficient TiO2–x new ternary materials with multistep electron transfer toward solar energy conversion (like CO2 reduction and H2 evolution).
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ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2017
·Vol. 24
·期 30
·23538-23548
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IF 2.741
Tang Fenglin,Xin Jia,Zheng Xilai,Zheng Tianyuan,Yuan Xianzheng,Kolditz Olaf
A microscale zero-valent iron (mZVI)-based in situ reactive zone is a promising technology for contaminated groundwater remediation. Estimation of mZVI aging behavior after its injection into the subsurface is essential for efficiency and longevity assessments. In this study, batch tests were conducted to investigate the effect of initial pH on mZVI aging dynamics, as well as the formation and evolution of aging products over 112 days. Results indicated that mZVI aging accelerated with decreasing initial pH. Corrosion rates of mZVI particles under pH 6.0 and 7.5 were approximately two orders of magnitude higher than those observed at pH 9.0. The morphological, structural, and compositional evolution of mZVI particles in three systems (pH = 6.0, 7.5, and 9.0) were investigated using scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. In acidic and neutral solutions, a thick passivation layer with loosely and unevenly distributed aging precipitates was observed, and Fe 3 O 4 was the final aging precipitate. Nevertheless, in alkaline solutions, minute aging precipitates were detected on the mZVI surface at 112 day. Characterization results suggested that mZVI was oxidized via the Fe 0 –Fe(OH) 2 –Fe 3 O 4 route. These findings shed new light on mZVI aging mechanisms, particularly its physicochemical characteristics and the structural evolution of mZVI in field-scale groundwater remediation applications.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2017
·
IF 9.446
Piyong Zhang,Ting Song,Tingting Wang,Heping Zeng
Cu nanoparticles (NPs) are low-cost plasmonic metals and have been used for photocatalytic hydrogen evolution due to their surface plasmon resonance (SPR) effect. An efficient photocatalyst consisting of plasmonic Cu NPs on reduced graphene oxide (rGO) nanosheets support (Cu/rGO) is successfully prepared by a facile in-situ photoreduction process to form multiple nanoscale junctions for enhancement of photocatalytic hydrogen evolution. Compared to individual Cu NPs, the coupling to rGO nanosheets produces a higher photocatalytic ability with the highest H 2 evolution rate of 59 mmol g −1 h −1 for sample C , which contains 1.0 wt% of rGO nanosheets. The rGO nanosheet possesses an extremely high conductivity and, can accept and transfer photogenerated electrons with no barrier. Therefore, recombination of photoinduced charges can be efficiently suppressed and the accepted electrons can be rapidly transferred to reactive sites for H 2 evolution across its two-dimensional plane. More importantly, a near-infrared photocatalytic activity for sample C was obtained under monochromatic light irradiation at 800 and 900 nm due to the broad spectrum response of plasmonic Cu NPs. Furthermore, a possible reaction mechanism is proposed for the photocatalytic activity improvement as well as the detailed charge transfer condition.
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