查看更多>>摘要：Direct photocatalytic water splitting is an attractive strategy for clean energy, in which, organic photocatalytic systems with broad light-harvesting region and efficient charge separation are highly desired and still challenging. In this paper, three multi-branched organic dyes were designed and synthesized with dipolar, V-shaped, and octupolar geometries, respectively. The multiple intramolecular charge transfer processes by electronic pull-push effect along the branches can provide more channels for light-harvesting and carrier transporting. Also, the interactions with polymeric carbon nitride (PCN) can be optimized by multiple anchoring units and defect filling effect, resulting in the gradually enhanced photocatalytic hydrogen evolution performance with the increased number of branches. Accordingly, the highest one of 996.9 mu mol h(-1) was achieved, which is over 40-folders that of PCN/Pt (24.8 mu mol h(-1)) under the same conditions. It provides an efficient strategy for molecular design of organic dyes as photocatalyst, promoting development of PHE system from the molecular level.
查看更多>>摘要：Urea perylene imide polymer (UPDI) is successfully recombined with Co(NO3)(2) molecules into one-dimensional nanocrystals (Co-UPDI) for enhanced photocatalytic oxygen evolution (POE) under visible light. Co-UPDI as photocatalyst exhibits more an order of magnitude of POE rate than UPDI at pH = 4.8 (8.00 vs. 0.58 mmol h(-1)g(-1)), which is the highest among reported POE tests in aqueous colloid system with AgNO3 as sacrificial agent. The apparent quantum yield (AQY) reaches 4.39 % at 450 nm. The systematical experiments reveals that the heterojunction formation between UPDI line and Co(NO3)(2) molecules is crucial through the coordination of Co with N atoms. Consequently, the rigidity of UPDI line enhances, H-type stacking of PDI moiety becomes closer, and CoOOH as cocatalyst in-situ forms during POE. Meanwhile, more excitons with longer lifetime generate and more quickly transfer in Co-UPDI than UPDI nanocrystals. This work provides an efficient strategy for photocatalytic water oxidation.
查看更多>>摘要：Aerobic hydroxylation of phenylboronic acids to phenols has attracted considerable attention but is exceedingly challenging due to the obstacle in the activation of oxygen (O-2). Here, two carbazole-based conjugated micro porous polymers (CMPs), namely TCB-CMP and EFC-CMP, were fabricated through polymerization of 1,3,5-tri (9H-carbazole-9-yl)benzene (TCB) and 9,9 '-(9,9-diethyl-9H-fluorene-2,7-diyl)bis(9H-carbazole) (EFC), respectively. Gratifyingly, with N,N'-diisopropylethylamine (DIPEA) as the hole (h(+)) quencher, blue light photo catalysis of both carbazole-based CMPs could execute the aerobic hydroxylation of phenylboronic acids in ethanol (C2H5OH). Importantly, the EFC-CMP imparted superior photocatalytic activity to TCB-CMP due to the favorable reduction of O-2 to superoxide anion (O-2(center dot-)) by electron (e(-)). Thereby, O-2(center dot-) conducted the highly selective aerobic hydroxylation of phenylboronic acids. The aerobic hydroxylation of a wide range of phenylboronic acids to corresponding phenols was achieved with high yields. The work further demonstrates the feasibility of taming the oxidation potential of CMPs in producing delicate products like phenols.
查看更多>>摘要：This work reports a novel strategy to activate type III heterojunction through introducing defect sites at the interfaces and making use of the defect band as the bridge for storage, secondary excitation, and interband transfer of the photothermal induced charges for constructing two-component Type B heterojunction photothermocatalyst. Type III heterojunction WO3-x/GdCrO3 is activated by defect-band state W5/4+ at WO3-x interface under photothermal conditions, achieving efficient charge separation, high redox potential, and full visible light absorption. The as-bridged (or Type B) heterojunction WO3-x-R/GdCrO3 as non-noble metal catalyst demonstrates excellent photothermocatalytic performance in toluene degradation with a reaction rate five times higher than that of WO3-x/GdCrO3 with less interfacial defect sites as well as in CO2 reduction with high CO and CH4 yielding rates of 49.6 mu mol g(-1) h(-1) and 18.5 mu mol g(-1) h(-1) in gas-solid reaction system without sacrifice agent, evidently better than those reported in the literature.
查看更多>>摘要：The abatement of harmful nitrogen oxides (NOx) emission during vehicle cold start is challenging. Passive NOx adsorbers (PNAs) have proven to effectively alleviate NOx emission at low temperatures. In this work, Pd-based Na-SSZ-13 (Pd/Na-13) was synthesized and hydrothermally aged to investigate the effect of Na co-cations on the structure and activity of Pd/SSZ-13 for low-temperature NO adsorption. Compared to Pd-based NH4-SSZ-13 (Pd/NH4-13), Pd/Na-13 exhibited superior stability and activity promoted by Na co-cations in SSZ-13. DRIFTS and Al-27 MAS NMR demonstrated that Na co-cations protected Si-O(H)-Al bonds and thus helping to mitigate dealumination during hydrothermal aging. NO- and CO-DRIFTS studies proved that Pd2+ sites existed in aged Pd/Na-13 dominantly. Strikingly, the aged Pd/Na-13 exhibited excellent adsorption capacity with additional NO adsorption at above 100 degrees C. Our work reveals the co-cation effects on the local environments of Pd/SSZ-13, expecting to provide guidance on the catalyst modification or optimization for low-temperature NO adsorption.
查看更多>>摘要：In this study, bimetallic phosphides were reported to be novel, efficient, and stable activators of perox-ymonosulfate (PMS). CoFe2Px was synthesized by phosphorization of CoFe2O4 and applied in PMS activation for sulphachloropyridazine sodium (SCP) degradation. The SCP removal reached up to 94.2% in 30 min, with a reaction rate of 0.090 min(-1). Particularly, CoFe2Px exhibited much lower cobalt ion leaching (0.082 mg L-1) than the reported cobalt-containing catalysts, due to the more intimate Co-Fe interaction and the surrounding of metals by phosphorus. Different from the free radical pathway in CoFe2O4 /PMS system, a radical-nonradical coupling process was detected in CoFe2Px /PMS system, which was confirmed by quenching tests, electron paramagnetic resonance (EPR) measurements, and transformation intermediate analyses. Moreover, CoFe2Px demonstrates favorable durability for PMS activation and potential practicability for realistic wastewater treatment. This work provides new insights for rational design and mechanism exploration of transition-metal phosphides (TMPs) in the environmental catalysis field.
查看更多>>摘要：While semiconductor nanocrystals with different crystal forms typically show different catalytic performances, such behavior has been scarcely documented for metal-organic frameworks (MOFs). Herein, two Ni-MOF catalysts with different crystal forms have been successfully prepared and used in photo-reduction of CO2. With a prolonged lifetime (5 h vs 2 h) and higher yield of the product CO (34 mu mol vs 18 mu mol), Ni-MOF(H2O) demonstrates a much better performance than Ni-MOF. Theoretical studies reveal that the adsorption energy of a CO2 molecule is more negative on Ni-MOF(H2O) than on Ni-MOF (-0.85 eV vs-0.62 eV). Furthermore, the transfer and separation of the photo-generated charge carriers are also more efficient in the Ni-MOF(H2O) system. This study not only presents a superior Ni-MOF catalyst but also promotes the fabrication of highly active catalysts for the photo-reduction of CO2.
查看更多>>摘要：Supported metal clusters are considered as promising cocatalysts in heterogeneous photocatalysis due to their singular geometric structures and unique reactivity. Nevertheless, to explore efficient synthetic routes that result in stable supported clusters with tailored active sites is an urgent yet challenging task. Here, a photocatalyst with highly dispersed Pd clusters onto TiO2 is synthesized through only one-step ball milling procedure. The obtained Pd clusters form a particular metal-support interface, which has the ability to rearrange the small clusters evolving into Pd nanoparticles during the photocatalytic H-2 production process, and maintain a stable photocatalytic performance up to 100 h of continuous operation. Moreover, the unique interaction between Pd clusters and titania support was only observed in the ball-milled sample, and it disappeared after a calcination treatment. The mechanochemical strategy paves the way to stabilize supported metal clusters onto semiconductors without any organic compounds involved.
查看更多>>摘要：Cost-effective and highly abundant oxygen evolution reaction (OER) electrocatalysts are of tremendous research interest in a variety of energy storage and conversion technology fields. However, the commercial applications are greatly impeded due to the sluggish OER kinetics. Herein, a heterostructured Co9S8@MoS2 electrocatalyst is demonstrated by elaborately implanting polyoxometalate of PMo12 into zeolitic imidazolate frameworks (ZIFs). The implantation of Mo species creates abundant Co9S8/MoS2 hetero-interfaces that could fine-tune the electrocatalytic activity of cobalt sites and thereof enhance the OER activity. Density functional theory (DFT) results prove synergetic effects between Co9S8 and MoS2 at the heterotinterfaces. The heterostructured Co9S8 @MoS2 catalyst achieves a low overpotential of 242 mV to reach 10 mA cm(-2) and the corresponding Tafel slope is as small as 58 mV dec-1. Based on the superior OER activity, an unbiased solar water splitting system is built by integrating perovskite solar cell with the two-electrode Co9S8 @MoS2//Pt/C, yielding a high solar-to-hydrogen (STH) conversion efficiency of 13.6%. This study demonstrates a new approach for cost-effective solar water splitting system toward green hydrogen production.
查看更多>>摘要：Herein, we developed and evaluated an electrochemical periodate (PI) activation system for the ultrafast degradation of aqueous micropollutants (tau < 3 s). Filters constructed from carbon nanotubes (CNT) coated with Fe2O3 nanoparticles on the outer (Fe2O3-out-CNT) and inner surfaces (Fe2O3-in-CNT) were prepared to regulate the generation of reactive oxygen species (ROS) during PI activation. The activation function of the electroactive nanohybrid filters lay in their ability to facilitate the redox cycling of Fe(III)/Fe(II) assisted by an electric field. The results showed that a non-radical (i.e., O-1(2)) pathway dominated the degradation process in the electro/ Fe2O3-in-CNT/PI system, while a contrastive radical pathway (i.e., HO center dot and IO3 center dot) was identified in the electro/ Fe2O3-out-CNT/PI system. The electro/Fe2O3-in-CNT/PI system exhibited enhanced catalytic activity towards the micropollutants degradation relative to its electro/Fe2O3-out-CNT/PI counterpart. Density functional theory calculations suggested that PI could be directly decomposed under the nanoconfined environment, rather than forming a stable adsorption complex in the unconfined system.
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Elsevier