Denny, Steven R.Lin, ZhexiPorter, William N.Artrith, Nongnuch...
8页
查看更多>>摘要：Ethanol is the smallest molecule containing C-O, C-C, C-H, and O-H bonds present in biomass-derived oxygenates. The development of inexpensive and selective catalysts for ethanol reforming is important towards the renewable generation of hydrogen from biomass. Transition metal nitrides (TMN) are interesting catalyst support materials that can effectively reduce precious metal loading for the catalysis of ethanol and other oxygenates. Herein theoretical and experimental methods were used to probe platinum-modified molybdenum nitride (Pt/ Mo2N) surfaces for ethanol reforming. Computations using density-functional theory and machine learning predicted monolayer Pt/Mo2N to be highly active and selective for ethanol reforming. Temperature-programmed desorption (TPD) experiments verified that ethanol primarily underwent decomposition on Mo2N, and the reaction pathway shifted to reforming on Pt/Mo2N surfaces. High-resolution electron energy loss spectroscopy (HREELS) results further indicated that while Mo2N decomposed the ethoxy intermediate by cleaving C-C, C-O, and C-H bonds, Pt-modification preserved the C-O bond, resulting in ethanol reforming.
查看更多>>摘要：The removal of algae by reactive oxygen species (ROS) through photocatalytic O-2 activation is still a challenge. Herein, we constructed a van der Waals (VDW) heterojunction photocatalyst by coupling BiO2-x with Bi3NbO7 for photocatalytic inactivation of Microcystic aeruginosa and photodegradation of Microcystin-LR. The oxygen vacancies in BiO2-x/Bi3NbO7 can effectively promote the chemisorption of O-2, and the VDW force can drive the photoelectrons in Bi3NbO7 transfer to BiO2-x through S-scheme transfer path, resulting more electrons reduce O-2 to center dot O-2(-). Hence, photocatalytic inactivation of algae by BiO2-x/Bi3NbO7 is 14.17 and 19.05 times higher than BiO(2-x)and Bi3NbO7, respectively. During the photocatalysis, the center dot O-2(-) damages the antioxidant system and cell membrane of algae, resulting in the release of organic matter and Microcystin-LR and finally causing the death of algae. The three-dimensional fluorescence spectroscopy indicates BiO2-x/Bi3NbO7 can further availably photo-degrade the organic matter, and four possible photodegradation pathways of MC-LR are proposed.
查看更多>>摘要：Quinacridone (QA) derivatives, one of cost-effective dyes with intriguing optical activity, have been extensively investigated in many fields such as organic light-emitting diodes, organic solar cells, and photocatalysis. Herein, a new QA-monomer (QA-PCHO) with a zigzag configuration was synthesized via N-arylation of benzene halide and quinacridone. The new monomer could enrich eventual structural diversity of the corresponding covalent organic frameworks (COFs). And based on the precursor, we developed two new QA-based 2D imine COFs with large pore size (> 4.7 nm) which exhibited superior photocatalytic activity toward Povarov reaction with broad substrate scopes and excellent functional group compatibility.
查看更多>>摘要：Heterogeneous-homogeneous coupled Fenton (HHCF) processes compromise the merits of rapid degradation and catalyst reusability, thus are very attractive for environmental remediation and water treatment. However, the development of HHCF processes suffers from the lack of desirable catalysts and Fe(III)/Fe(II) redox cycle (iron cycle) mediators. Herein we demonstrate the combination of hydrogen peroxide, ferric phosphate and hydroxylamine offers a promising HHCF process, where ferric phosphate and hydroxylamine serve as the catalyst and iron cycle mediator, respectively. Hydroxylamine can realize suitable iron release from ferric phosphate, effective iron cycle, and center dot OH consumption, resulting in efficient conversion of H2O2 to center dot OH for sulfamethazine removal. More importantly, the phosphorus release from ferric phosphate and nitrogen residual during this HHCF process are limited to reduce the risk of secondary pollution. This study clarifies the importance of iron dissolution and iron cycle on highly efficient Fenton processes, and also provides a promising antibiotic pollutant removal strategy.
查看更多>>摘要：Water pollution is a major global issue that is causing tremendous threats to human health as well as to aquatic lives. This is triggering the need to develop efficient catalysts which can not only eliminate various water pollutants, but also cost-effective to use in a large-scale application. In this scenario, the biomass-derived porous carbon-supported catalyst which can catalyze multiple reactions to remove water pollutants is very much pertinent. Herein, we have synthesized a catalyst in which Cu and CoFe2O4 nanoparticles (CF) are anchored on the hierarchical porous carbon (PC) derived from coconut fibers. The catalytic efficiency of this catalyst (Cu-CF-PC) was tested for the removal of two major water pollutants, i.e. nitroaromatic compounds and antibiotics. Cu CF-PC reduced various aromatic nitro compounds in presence of NaBH4 within 0.5-3 min via a six electron transfer route. Furthermore, Cu-CF-PC also successfully degraded four commonly used antibiotics (Amoxicillin, Ciprofloxacin, Tetracycline hydrochloride, and Sulfamethoxazole) within 1 min. Degradation of antibiotics proceeds via a Z-scheme heterojunction formation in the catalyst under microwave irradiation which leads to the generation of (OH)-O-center dot radicals that degrades the antibiotic molecules. Moreover, the catalyst can be easily recovered from the reaction mixture by using an external magnet and reused. The catalyst was structurally and morphologically stable and showed ~92% catalytic efficiency even after five cycles. Hence, this work puts forward a reusable, cost-effective, environment-friendly, and highly efficient catalyst (Cu-CF-PC) that can be used in the practical approach to remediate environmental pollution.
查看更多>>摘要：Constructing non-noble robust catalysts for deep catalytic oxidation of obstinate light alkanes at low temperature is of great value and significance. Herein, we designed a facile solvent-thermal-reduction strategy to fabricate an O-vacancy-rich porous MnO2 nanosheet (MnO2- PS) catalyst for propane catalytic oxidation. The abundant vacancies in MnO2- PS catalysts can significantly promote its redox ability and oxygen activation capacity, and then provide more active oxygen species with enhanced oxygen mobility and reactivity, thus accelerate the cleavage of C-H bond and the decomposition of intermediates. Meanwhile, benefiting from the porous nanosheet structure, MnO2- PS catalyst possesses highly accessible surface and high density of exposed active sites, thus facilitating the adsorption and the activation of reactant molecule. At the same time, the catalyst also exhibits good thermal stability and water resistant ability. This robust and efficient catalytic system may provide some enlightenments for designing feasible catalyst with high-performance for deep catalytic destruction of VOCs.
Jin, XiaoyanKim, Min GyuHwang, Seong-JuKim, Hyun Kyu...
13页
查看更多>>摘要：High-performance electrocatalysts have attracted growing interest because of their crucial roles in renewable energy technologies. In this study, the host, interlayer, and surface features of electrocatalytically-active 2D nanosheets (NSs) are systematically controlled with the synergetic combination of host-guest co-engineering and surface modification to develop a novel synthetic strategy for efficient electrocatalysts. Molecular-level control of interfacial electronic coupling and surface reactivity can be achieved by the self-assembly of MoS2/ RuO2 NS mixtures with variable-sized tetraalkylammonium cations and subsequent thermal aging. The resulting optimization of the operation mechanisms of restacked MoS2/RuO2 NSs effectively improves the electrocatalyst functionality for hydrogen evolution reaction (HER). The extensive modifications of diverse structural and morphological parameters allow the elucidation of a linear correlation between electrochemical active surface area and HER overpotential. Systematic in-situ spectroscopic analyses clearly demonstrate the crucial role of enhanced Volmer-Tafel mechanism in improving the electrocatalytic activity via enhancement of proton adsorption and interfacial electron transfer.
查看更多>>摘要：The design of cathodic catalysts layer (CCL) consisted of Platinum Group Metal-free (PGM-free) electrocatalysts was done by catalyst coated membrane approach. Three different Fe-Mn-N-C compounds were synthesized with Fe:Mn ratio of 1:1, 2:1 and 2:1 with modified heat treatment profile. The catalysts were characterized by X-ray photoelectron spectroscopy, X-ray powder diffraction, pore and particle size distribution, zeta potential and transmission electron microscopy. Electrocatalysts were integrated into membrane electrode assembly and evaluated by electrochemical methods. Electrochemical impedance spectroscopy in combination with modeling were used for estimation of proton conductivity of CCL and its oxygen diffusivity. It was found that all CCLs possess extremely high proton conductivity, which was demonstrated for the first time for these types of PGMfree catalysts. The observed ORR mechanism was predominantly 4e- due to peroxide/radicals scavenging effect of Mn.
查看更多>>摘要：Oxygen evolution reaction (OER) in pH-neutral electrolyte is considered more difficult for the additional adsorption and the dissociation process of H2O. Herein, by in-suit construction of the heterostructure between MgO and NiCo2S4 on carbon cloth (CC), a novel MgO/NiCo2S4 heterostructure on CC (MgO/NCS-CC) is successfully fabricated. Benefitting from the optimized electronic structure attributed to the construction of heterointerface, and the intense adsorption of H2O on the surface of catalysts owing to the introduction of hydration-effect-promoting (HEP) element Mg, the MgO/NCS-CC exhibits outstanding OER activity with overpotential of 145 mV at the current density of 10 mA.cm(-2) in pH-neutral electrolyte and can maintain stability over 40 h. Density-functional theory (DFT) also demonstrates that the MgO/NiCo2S4 heterostructure can effectively adjust the electronic structure and enhance the adsorption of reactant, thus further optimizing Gibbs free energies and improving the activity for OER in pH-neutral electrolyte.
Boukha, ZouhairGonzalez-Velasco, Juan R.Gutierrez-Ortiz, Miguel A.
11页
查看更多>>摘要：The viability of gold supported on lanthanum-modified HAP catalysts is investigated for CO preferential oxidation (PROX) in H-2-rich stream. All samples comprise small nanoparticles (NPs) of Au (< 4 nm). Addition of La enhances the chemisorption of CO, whereas it lowers that of H-2 and H2O. Moreover, lanthanum improves the reducibility of the catalysts and the mobility of oxygen. FTIR studies show that under CO oxidation conditions Au exists in two distinct forms on La-promoted samples, namely Au sigma+ and Au+ species. The catalytic tests under different PROX conditions show an improvement of the performance with lanthanum addition. The observed improvement is linked to suitable chemical properties, whereas efficiency dependence on Au NP sizes is rather secondary. At 80 degrees C, La-rich catalysts completely eliminate CO and prove to be selective (66%) under realistic PROX conditions (in the presence of H2O and CO2). Moreover, they are exceptionally stable during an extended period (240 h).
NSTL
Elsevier