查看更多>>摘要：Electrocatalytic N-2 reduction reaction (NRR) serves as a promising approach for converting N-2 to NH3 in a sustainable way to replace the energy-intensive Haber-Bosch process. MoS2-based electrocatalysts hold great potentials in catalyzing N-2 reduction due to their similarity with active MoFe-co in biological nitrogenase. In this work, we reported a sulfur vacancy-rich MoS2 as an excellent electmcatalyst for NRR, where the sulfur vacancies (SVs) were easily controlled by regulating the amount of P dopants. MoS2 with abundant SVs (P-M-1) achieved a large NH3 yield rate of 60.27 mu g h(-1) mg(cat)(-1). and high Faradaic efficiency of 12.22% towards NRR. Further mechanistic study revealed that P dopants not only created SVs as the active centers but also modulated the electronic structure for the enhanced adsorption and activation of N-2 molecules, thus immensely promoting the catalytic performance of NRR.
查看更多>>摘要：Herein, a novel hexapod-like pyrite nanosheets mineral cluster was prepared via a facile hydrothermal method. Compared with classical homogeneous Fenton processes, this catalyst possessed a higher adsorption capacity and catalytic activity to ciprofloxacin (20 mg/L), which could be completely degraded within 10 min at pH 4.0. center dot OH was the main reactive oxygen species responsible for ciprofloxacin degradation. Br- (> 1 mM), I- (> 1 mM), and high concentration of F- ions (> 10 mM) exhibited an inhibition effect on ciprofloxacin degradation, but the Clions (0-100 mM) did not show obvious effects on ciprofloxacin removal. Thirteen intermediates were qualitatively identified, and degradation mechanism was tentatively proposed for ciprofloxacin. Several toxic intermediates were produced, but they could be fully mineralized and detoxified by this heterogeneous Fenton catalyst after 30 min reaction. The work provides a novel heterogeneous Fenton catalyst to purify and detoxify antibiotics as well as other refractory organic pollutants contaminated wastewater.
查看更多>>摘要：Modification of TiO2 with copper oxides clusters (CuOx-TiO2) induces visible-light absorption and enhances its activity. In this work, we investigated the CuOx-anatase and CuOx-rutile for the photocatalytic oxidation of gaseous NH3 under visible light. In contrast with the widely reported results that CuOx-anatase displays higher performance than CuOx-rutile in photocatalytic oxidation or reduction, we surprisingly observed that CuOx-rutile is able to oxidize NH3 efficiently under visible light irradiation, while CuOx-anatase shows no activity. Further characterizations showed that visible-light inclines to drive the VB electrons of rutile TiO2 to CuOx at the interface between rutile TiO2 and CuOx, while it drives the electrons of CuOx to anatase TiO2 at interface between anatase TiO2 and CuOx. DFT calculations revealed that the interaction between CuOx and TiO2 is markedly different in CuOx-anatase and CuOx-rutile, which induces the differences in the electronic distribution of interfacial Cu, O and Ti atoms, resulting in the distinct direction of charge transfer.
查看更多>>摘要：Polymeric carbon nitride (C3N4) is a very attractive candidate to produce photocatalytic hydrogen peroxide (H2O2) due to its low-cost, metal-free characteristics. However, the low efficiency would limit its development to higher yields because of insufficient light absorption and electron-hole separation. Here, we developed a simple method to anchor CN quantum dots (QDs) onto g-C3N4 nanosheets to form a homojunction structure (HJ-C3N4), which could improve photocatalytic performance largely without introducing metal elements. Its superior efficiency is a result of the band alignment by the homojunction structure providing excellent electron-hole separation and QDs providing suppressed recombination. Simultaneously, the light responsiveness of QDs endows a wide spectrum-responsive adsorption and enhances the adsorption intensity. The H2O2 yield of the HJ-C3N4 reached 115 mu mol L-1 h(-1) in pure water by visible light, which has an 8.6x higher production than g-C3N4 nanosheets. The material design of 0D/2D homojunction could be extended to other materials with specific band alignment.
查看更多>>摘要：It is highly desirable to make full use of photogenerated charge carriers by elaborately designing high-efficiency multifunctional photocatalysts with achieving bi-value-added production. Herein, we report the photocatalyst with ultrathin ZnIn2S4 nanosheets decorating polypyrrole nanotubes, thanks to the matched bandgap, is capable of harvesting visible light for photocatalysis, during which the photoexcited electrons and holes are used for H-2 evolution and 1,4-benzenedimethanol (BDM) upgrading oxidation, respectively. Comprehensive experiments and density functional theory calculations indicate that the photoinduced electrons tend to be transferred to the inner PPy nanotubes of PPy@ZIS composite for photocatalytic H-2 generation, while the photoexcited holes favorably oxidize BDM into 1,4-phthalaldehyde (PAD) on outer ZIS nanosheets of PPy@ZIS composite. The optimized PPy@ZIS exhibits an apparent quantum efficiency of 6.43% (at 420 nm) for photocatalytic H-2 evolution and BDM valorization into PAD at a rate of 735 mu mol g(-1) h(-1), remarkably promoting the utilization efficiency of charge carriers.
查看更多>>摘要：The CdxInyS(x+1.5y) catalysts with gradient Cd:In ratios were controllably synthesized via an one-step hydrothermal approach. Particularly, the hydrothermal synthesis conferred those CdxInyS(x+1.5y) catalysts with Cd:In ratios over 1:2 with a one-dimensional-three-dimensional heterojunction structure composed of CdS nanorods and cubic-phase CdIn2S4. Our characterization evidences reflected that the CdS nanorods effectively promoted the separation of photoexcited electron-hole pairs in CdxInyS(x+1.5y) and enabled transboundary transfer of photogenerated carriers. Spectroscopic and experimental results were further employed to develop a detailed catalytic mechanism, in which the superoxide anion (center dot O-2(-)) plays an important role in the catalytic oxidation of HMF to DFF by CdxInyS(x+1.5y). Unlike other photocatalysts with center dot O-2(-) as the main active species, Cd1.5In2S4.5 gives an excellent performance in HMF conversion. This shows the great potential of cadmium-indium sulfides as photocatalysts for biomass conversion under ambient conditions.
查看更多>>摘要：Selective synthesis of higher alcohols from syngas conversion is highly desirable, but still very challenging. Here, focusing on the commonly used CuCoAl (CCA) catalyst, we attempted to reconcile the capability of the non-dissociation of CO species and the activation of H-2 through adding ZnO modified ZrO2 composite into the catalyst for the promotion of higher alcohols synthesis. Under the guidance of such concept, a series of CCA vertical bar ZnO/ZrO2 (m: n) modified catalysts (m: n, represent the mass ratio of ZnO to ZrO2) were prepared by mortar-mixing CuCoAl and ZnO/ZrO2 components (2/1 wt ratio). It was found that the CCA vertical bar ZnO/ZrO2 (4:1) catalyst showed a highest total alcohols (ROH) selectivity of 42.6 wt% with excellent C2+OH/ROH fraction of 83.7% among the investigated catalysts. The surface [H*]/[C*] ratio of CCA vertical bar ZnO/ZrO2 catalysts, as revealed by (CO + H-2)-TPD-MS results, increased with the rise of ZnO/ZrO2 ratio. Moreover, the CCA vertical bar ZnO/ZrO2 (4:1) catalyst with moderate [H*]/[C*] ratio could acquire the highest ROH selectivity and best space time yield of total alcohols (STYROH) due to that the balance of relative amount of CO*, CHx* and H* species provided the more probability of CnHx*-CO* coupling reaction for higher alcohols synthesis, rather than the hydrogenation reaction of CHx* or CnHx* species and water gas shift reaction.
查看更多>>摘要：Designing highly efficient photocatalysts is significantly important to degrade the harmful pollutions in water. In this study, photocatalyst of Fe3O4-ED-rGO with dissolved HPV was successfully prepared and electron microscopy characterization revealed that large number of single tungsten/vanadium atom oxide (ST/VAO) was homogeneously deposited on Fe3O4 nanoparticles in SMAO-MrGO-ED sample and occupied the bivalent Fe2+ sites. Meanwhile, phase analysis confirmed that the Fe3O4 nanocomposites were mostly conversed from the reducted Fe2O3 by the hydrolysis of rGO-ED-HPV. Such a highly dispersed monatomic adsorption on the bivalent Fe2+ of polycrystalline SMAO-MrGO-ED nanocomposite not only benefits for the visible light absorption from 2.7 eV to 2.10 eV, but also offers abundantly active sites to get the highest activity of 98.43% and 98.12% for ciprofloxacin (CF) and ibuprofen (IBF) photodegradation, respectively. All these discoveries give us a new insight to design the photocatalysts with high photodegradation efficiency, low cost, short reaction time and good reusability.
Kim, YongminXu, ShichengPark, JoonsukDadlani, Anup Lal...
10页
查看更多>>摘要：Improved activity and stability Pt-based catalysts for the oxygen reduction reaction (ORR) are needed to perpetuate the deployment of polymer electrolyte fuel cells (PEFCs) in the transportation sector. Here, we use atomic layer deposition of TiO2 and Pt coupled with thermal reductive annealing to prepare Pt3Ti electrocatalysts. The atomic level synthetic control resulted in Pt3Ti nanoparticles with high ORR performance, including a mass activity of 1.84 A/mgPt and excellent electrochemical stability. The Pt3Ti nanoparticles show excellent specific activity - 5.3-fold higher than commercial Pt/C and 3-fold higher than polycrystalline Pt, exceeding the performance of any PtTi catalysts reported to date. Combined experimental and computational efforts indicate that Pt enrichment on the Pt3Ti enhances the activity, and the intrinsic stability of the Pt3Ti phase provides durability. This knowledge, along with the facile fabrication of alloys by atomic layer deposition, can be leveraged to designed improved performance catalysts.
查看更多>>摘要：Methane has emerged as an important energy source and chemical feedstock, and thus breakthrough strategies for the direct partial oxidation of CH4 into small oxygenates have been desired. Here, CO-assisted CH4 conversion towards C1 and C2 oxygenates over zeolite-supported single-atom Rh catalysts was demonstrated, and the key role of CO, as an indispensable additive, and the reaction mechanism were experimentally investigated. Step-bystep introduction of the reactants resulted in the formation of stoichiometric amounts of product. Replacement of O2 by H2O2 revealed that gaseous O2 acts as a true oxidant, and CO enhanced the reaction as a ligand. The critical effect of acid sites in the formation of the C2 product was also confirmed. Based on these results, a plausible reaction mechanism was proposed. Finally, a small-pore zeolite, SSZ-13, was found to be superior for the selective production of methanol.
NSTL
Elsevier