Kim, YoungminKim, Jeong-RangKim, Tae-WanLee, You-Jin...
13页
查看更多>>摘要：A series of Ni/Al(1)Ce(a)O(x )composites prepared by various synthetic methods, including one-pot anion-cation double hydrolysis (CADH), co-precipitation (CP), CADH followed by wet impregnation (CADH-WI), and CP followed by wet impregnation (CP-WI) were employed as catalysts for ammonia (NH3) decomposition to generate hydrogen. The results revealed that the catalyst prepared by the one-pot CADH method exhibited outstanding catalytic performance (complete NH3 decomposition at around 550 ?) mainly because of significant enhancement in Ni dispersion, Ni reducibility, the quantity of surface oxygen vacancy, and NH3 adsorption af-finity. The superior catalytic performance of Ce-containing catalysts over Ni/Al2O3 catalyst was ascribed to the synergistic effects of NiO reducibility, surface oxygen vacancies, basicity, and Ni-support interaction. The selected catalysts demonstrated excellent stability during 100 h continuous operation, without any obvious decrease in NH3 conversion. Overall, the proposed one-pot CADH method offers great advantages in preparing highly active and stable Ni-based catalysts for NH3 decomposition.
查看更多>>摘要：Oxygen vacancy (VO) engineering can efficiently improve the catalytic activity of metal oxides. This work developed a solvent-free mechanochemical method to tailor VO levels on the surface of commercial MnO2 under ambient conditions. After a typical ball milling treatment at 350 rpm for 20 min, the obtained VO-rich MnO2 activated peroxymonosulfate (PMS) to completely degrade tetrabromobisphenol (TBBPA) with a pseudo-firstorder rate constant of 0.21 min 1, being 22 times larger than that for non-milled MnO2. O-18-labeling tests confirmed that singlet oxygen was generated from both PMS and lattice oxygen of MnO2 as dominant active species for the TBBPA degradation. It was clarified that the catalytic activity of MnO2 depends on not only VO levels, but also the local environment of VO, i.e., VO-associated cations. The Mn4+/Mn3+ redox couple is more important than Mn3+/Mn2+, and VO improves the oxygen mobility in/on MnO2 and Mn4+/Mn3+ redox reactions for the activation of PMS.
Choi, Sun HeeNam, Suk WooYoon, Chang WonSohn, Hyuntae...
13页
查看更多>>摘要：Pt supported on ordered mesoporous silica (KIT-6) catalyst was examined for the dehydrogenation of homocyclic liquid organic hydrogen carriers (LOHCs, 1: MCH, 2: hydrogenated biphenyl-based eutectic mixture (H-BPDM)) conditions. The longer pore-residence time of the MCH molecules in the 3D bicontinuous pore structure of the Pt/ KIT-6 catalyst strongly affected the catalytic activity because a higher MCH concentration was achieved in the vicinity of the Pt active sites. Pt/KIT-6 catalyst exhibited a higher surface area, pore volume, and Pt dispersion with narrower particle size distribution (average Pt particle size: -1.3 nm). Therefore, higher LOHC conversion with faster hydrogen production occurred, with a higher hydrogen selectivity over Pt/KIT-6 compared with Pt/ SiO2 and Pt/Al2O3. Long-term experiment results indicated that the Pt/KIT-6 catalytic activity was stable over the reaction time than that of the other catalysts. No significant structural collapse occurred in KIT-6 during the dehydrogenation. Carbon coking was observed for all three samples.
查看更多>>摘要：Developing efficient bifunctional electrocatalyst for overall water splitting and conversion of biomass into value-added products at large current density is essential but challenging. Herein, a hierarchical Fe-doped Ni2P nanosheets hybridized with C on Ni foam (Fe-Ni2P@C/NF) was developed as a robust bifunctional catalyst with excellent catalytic activity for hydrogen evolution reaction (HER) with overpotentials of 75 and 313 mV at 10 and 1000 mA cm(-2), respectively, and as well as for OER with a lower overpotential of 269 mV at 400 mA cm(-2). Particularly, the integrated double-electrode electrolyzer for simultaneous HER and biomass-derived mono-saccharide oxidation reaction (MOR) using Fe-Ni2P@C/NF only requires a low voltage of 1.55 V to drive a current density of 100 mA cm(-2). Meanwhile, the value-added lactic acid is obtained at the anode. This strategy of coupling biomass oxidation to promote H-2 production can significantly reduce energy consumption and obtain additional high value-added products.
查看更多>>摘要：Electrochemical CO2 reduction reaction (eCO(2)RR) is a promising approach for the sustainable development of energy and environment, yet the control over selectivity of eCO(2)RR is challenging and entails intelligent active site design. Herein, we firstly propose dual-active sites design of Sn-x-Sb-y-O-GO nanosheets (NSs) for controlling the reaction pathways. The Sn-x-Sb-y-O-GO NSs catalyst possesses large-size ultrathin structure and controllable Sn/Sb ratio, strengthening the interaction at the active site with OCHO* intermediate. The optimized Sn-7-Sb-3-O-GO NSs exhibit a HCOOH selectivity of 96.5% and partial current density of -21.6 mA cm(-2). The experiments and theory calculations show that the introduction of Sb secondary active site can accelerate water activation for forming unique *H species and the binding strength of OCHO* key intermediates, thereby enhancing the HCOOH selectivity in eCO(2)RR. This work lends credence to the novel metal-metal dual-active sites design strategy for eCO(2)RR sustainable energy conversion.
查看更多>>摘要：Engineering the interface between two-dimensional materials and polymers is of great importance to improve their catalytic performance for oxygen reduction reaction (ORR). Hence, polyaniline (PANI)-functionalized porous Pd metallene (Pd@PANI metallene) is prepared via a two-step strategy. Due to the ultrathin porous nanosheets and interfacial structure, the Pd@PANI metallene possesses sufficient active sites and optimized electronic structure, which exhibits superior oxygen reduction performance in alkaline electrolyte. The mass and specific activities for Pd@PANI metallene are measured to 1.79 A mgPd(-1) and 2.96 mA cm(-2) , which are 11.9 and 9.30 times those of Pt/C (0.15 A mgPd(-1) and 0.32 mA cm(-2)), respectively. Additionally, the ORR performance and morphology of Pd@PANI metallene can be maintained after long-term stability testing, making it an excellent ORR catalyst. This work provides an effective interface engineering strategy to construct efficient two-dimensional ORR electrocatalysts to improve the performance.
查看更多>>摘要：Exploring the high-efficient two-electron oxygen reduction reaction (2e- ORR) catalysts is greatly significant for promoting hydrogen peroxide (H2O2) electroproduction. Herein, we have constructed a pyranoid-O-dominated graphene-like nanocarbon (GLC) material with high surface area, hierarchical porous structure, and abundant edge defects, through the high-temperature alkali activation of cellulose-based precursor. Benefiting from its integrated merits, the GLC electrocatalyst exhibits excellent 2e- ORR performance with high H2O2 productivity and ultrafast wastewater degradation ability. Interestingly, whether changing the carbonaceous precursor or alkali activator, all the as-prepared pyranoid-O-dominated GLC-based materials display high 2e- selectivity for the ORR. Based on further analogical experiments and theoretical analysis, the results reveal that the nature of 2e- selectivity on carbon-based materials is highly associated with the pyranoid-O dopants, rather than the surface oxygen-containing functional groups declared by the previous reports. These findings may bring new insight into the 2e- ORR selectivity of carbon-based electrocatalysts for H2O2 production.
查看更多>>摘要：Semiconductor doping is an effective strategy for improving the light absorption efficiency and the photo generated carrier transport in photocatalysts. However, bulk defects induced by doping act as recombination centers, accelerating the recombination of carriers, which is detrimental to the photocatalytic performance. In this study, a novel electric-assisted photocatalytic technique was developed to reduce the recombination of the carriers trapped by the defects. The technique involves applying a low external voltage to a self-doped TiO2 nanotube film, without any electrolyte and counter electrode. The remarkable improvement in the charge carrier dynamics under the electric assistance is attributed to the significant promotion of photogenerated electron fluxes and prevention of charge recombination. The electric-assisted photocatalytic technique is compatible with a liquid-or a gas-phase reactive system, e.g., water splitting, H2O2 synthesis, and CO2 photoreduction. The technique is sufficiently advanced to allow scale-up of the photocatalytic process from laboratory scale to industrial-scale.
查看更多>>摘要：Energy-efficient photocatalytic CO2 reduction (PCO2R) into sustainable solar fuels is a highly enticing challenge for simultaneous settling of energy and environmental issues. Herein, we illustrate the synthesis and photo catalytic performance of a judiciously designed plasmonic Au nanoparticles photodeposited on TiO2-decorated N-doped graphene (ANGT-x) heterostructure catalyst showing remarkably enhanced CO2 reduction activity with high selectivity for methane production. Compared to typical binary Au-TiO2 photocatalyst, the ANGT2 exhibited almost 60 times higher electron consumption rate (R-electron) value ~742.39 mu mol g(-1)h(-1) for the reduced products, which, to the best of our knowledge is the highest PCO2R rate ever reported under comparable conditions. The superior performance of ANGT2 catalyst is attributed to the synergistic contributions from improved light absorbance, enhanced CO2 uptake together with improved charge transfer kinetics and efficient suppression of photogenerated (e-h) recombination rate bestowed by seamless interfacial contact between Au NPs and N-graphene-TiO2 components.
查看更多>>摘要：Vast progress in semiconductor photocatalysis has been witnessed, while the earth-abundant insulators were seldomly explored. In this work, we exploited insulator BaSO4 as photocatalyst by constructing a novel branch of insulator-semiconductor heterostructure with the narrow-gap CuS. The finely designed BaSO4-CuS heterostructure achieved a tetracycline (TC) degradation pseudo-first-order kinetic constant of 1.4 x 10(-2) min(-1), which was 311, 21 and 18 times higher than that of BaSO4, CuS and their physical mixture, respectively. Density functional theory (DFT) calculations unraveled that the intense Cu-O covalent interaction created a specific channel for interfacial electrons transfer from semiconductor to insulator. The elevated redox potential of CuS is vital for the accumulation of center dot O-2(-) and motivation of center dot OH, thus remarkedly accelerating TC mineralization. Furthermore, the degradation pathway and intermediates of TC were thoroughly studied through LC-MS. The current work provides new perspectives to harvest visible-light-driven insulator photocatalysts and demonstrates its promising applications for environmental remediation.
NSTL
Elsevier