查看更多>>摘要：Urea electrolysis is regarded as an effective strategy for addressing energy and environment issues. Here, a hierarchical structure with intimate interfaces derived from two-dimensional metal-organic framework (MOF) was constructed by partial sulfurization for urea oxidation. The sulfurization treatment increases the specific surface area, remarkably improving the mass transfer and the exposure of active sites. Moreover, the hybridization at the interface induces electron redistribution and facilitates the electron transfer as confirmed by experimental measurements and theoretical calculations. The optimal catalyst delivers enhanced catalytic activity and durability, achieving a low driving potential of 1.326 V (vs. RHE) for urea oxidation at a current density of 10 mA cm-2 and negligible activity loss after durability test, which outperforms most previously reported non-precious catalysts. Our results demonstrate the great potential of MOF-derived materials as efficient catalysts for costeffective hydrogen production and urea fuel cells, offering bright prospect for energy-sustainable developments and mitigating water contamination.
查看更多>>摘要：We used CO2 as a carbon source for conversion to carbon nanofibers through the catalytic hydrogenation reaction on a Ni-Na/Al2O3 catalyst. The Ag+ adsorbed on carbon nanofibers could be spontaneously reduced through the oxidation-reduction reaction Ni + 2Ag+ -> 2Ag + Ni2+. The adsorbed Ag+ was reduced by the electrons released from Ni, forming Ag particles on the carbon surface. The Ag deposited on the magnetic carbon nanofibers was employed to remove contaminants in water, in which 4-nitrophenol was reduced to 4-aminophenol. The apparent rate of 4-nitrophenol reduction was significantly enhanced with increasing Ag concentration in the range of 0.5-2.6 wt%, from 8.5 x 10-3 to 1.25 x 10-1 s-1. The negative charge on the surface when Ag particles formed was assumed to be an important factor in enhancing the catalytic rate because of the increases in the coverage and adsorption rate of 4-NP on the catalyst surface.
Ali, Farhan S. M.Arevalo, Ryan LacdaoVandichel, MatthiasSpeck, Florian...
12页
查看更多>>摘要：For anion exchange membrane (AEM) electrolysis, challenges include finding an optimal catalyst for hydrogen evolution reaction (HER), as the noble metals are scarce while non-noble metals are inferior. Here, the noble metal amount is reduced in a straightforward solution synthesis which produces Pt-Ru surface nanoparticles and unique intratube nanowires decorated on single walled carbon nanotubes (SWNT). In half-cell tests, 5 wt(PtRu),-% Pt-Ru SWNT demonstrates stable 10 mA cm(-2) HER current at 46 mV overpotential and outperforms commercial electrocatalysts. When integrated in an AEM electrolyser, a high current density of 500 mA cm(-2) at a low voltage of 1.72 V is achieved with 34 mu g cm(-2) metal loading. First-principles calculations reveal that both the Pt-Ru alloy nanoparticle and intratube nanowires promote near optimal H* binding energy, thereby releasing the H-2 faster. Thus, our approach yields an active low metal loading alkaline HER catalyst without sacrificing the performance in an AEM electrolyser.
Marin, M. LuisaBosca, FranciscoBerruti, IlariaPolo-Lopez, Maria Inmaculada...
12页
查看更多>>摘要：Sulfate radicals (SO4 center dot-) reactivity against gram-negative (E. coli) and gram-positive (E. faecalis) bacteria and Contaminants of Emerging Concern (CECs) (Diclofenac-DCF, Sulfamethoxazole-SMX and Trimethoprim-TMP) was investigated through laser flash photolysis (LFP) technique. Analysis of the lifetime of SO4 center dot- in presence of cell-wall compounds of bacteria and CECs allowed determining reactivity of SO4 center dot- towards these compounds. Results showed that SO4 center dot- reacts with common cell-wall components through H-abstraction mechanism (kSO4 center dot  < 108 M-1s-1). By contrast, kSO4 center dot  > 109 M-1s-1 were found using aromatic amino acids (AAA) only present in Porins of the gram-negative outer-membrane. The intermediates detected from the reaction of SO4 center dot- with the AAA confirmed the involvement of electron transfer processes. Moreover, kSO4 center dot  values determined for DCF, TMP and SMX also agreed with an electron transfer mechanism. Interestingly, bacteria and CECs removal at pilot plant scale by UV-C/SO4 center dot- is in accordance with the kSO4 center dot  obtained using the LFP: E. coli > E. faecalis and DCF > TMP approximately equal to SMX.
查看更多>>摘要：Configuring Ni-based catalyst with superior activity and stability is one efficient strategy in achieving its application for VOCs catalytic combustion. Here, we report the rational design and synthesis of core-shell SiO2@NiaCobOx nanotube derived from three-layered C@SiO2@NiCo-Phyllosilicate nanofiber. Through a typical hydrothermal strategy, the hierarchical NiCo-Phyllosilicate ultrathin nanosheets are fitly grown on the surface of order mesoporous SiO2 nanotube, which is obtained through thermal treatment of core-shell C@SiO2 nanofiber in air. Whereafter, a core-shell SiO2@Ni2Co1Ox nanotube is obtained to achieve the highly efficient conversion of VOCs in the presence of 5vol%H2O. We observe this special structural design can own superior redox ability, provide active oxygen species (O-ads), and generate the abundant acid sites. Ideally, the low-temperature catalytic combustion of toluene over the core-shell SiO2@Ni2Co1Ox nanotube is realized through the combined action of Marse-van Krevelen (MvK) and Langmuir-Hinshelwood (L-H) mechanism. Simultaneously, a good thermal stability and water resistance is also achieved, which benefits from the guided growth of order mesoporous SiO2 nanotube, the presence of strong interactions (Ni-O-Si band) and the contribution of surface -OH groups in the special "fibrous " structure of phyllosilicate.
Ramon, Adriana P.Li, XianshengClark, Adam H.Safonova, Olga V....
16页
查看更多>>摘要：Dry reforming of methane (DRM) is a promising process to generate synthetic gas with a low H-2/CO ratio. The main issues in DRM are the deposition of carbon over the catalyst and active metal sintering. Pyrochlores and perovskites are stable materials with properties that can overcome these challenges due to the presence of well dispersed active metal and oxygen vacancies. La2Ce2O7 and LaNiO3 mixed oxides containing 5 wt% of nickel were synthesized by modified Pechini and hydrothermal methods. The reduction of the La2Ce2O7 and LaNiO3 mixed materials was followed by in situ X-ray diffraction, ambient pressure X-ray photoelectron spectroscopy (APXPS), and X-ray absorption near edge structure. An oxygen-deficient perovskite La2Ni2O5 was identified already at room temperature. Both catalysts were stable during the performance test at low-(600 degrees C) and high-(850 degrees C) temperature DRM reaction, thanks to a negligible carbon accumulation on the catalyst surface. The high amount of electrophilic oxygen species, oxygen vacancies and basic sites detected correlates with the high catalytic activity. The material synthesized by hydrothermal method showed the highest conversion and yield. The better performance in this catalyst was related to higher amount of intermediate basic sites, oxygen vacancies and greater interaction between nickel and cerium. The reaction mechanism proposed in these materials takes into account the intermediates CHx and adsorbed O/OH, which were observed by means of APXPS.
查看更多>>摘要：Two-dimensional (2D) Bi2WO6, Bi2MoO6, and Bi2WxMo1_xO6 (x = 0.1, 0.3, 0.5, 0.7, and 0.9) solid solution photocatalysts were synthesized using the hexadecyl trimethyl ammonium bromide-assisted hydrothermal method. All of the samples displayed a morphology of irregularly rectangular nanosheets with a thickness of 7.0-17.4 nm. The photocatalytic performance of Bi2WxMo1_xO6 was much better than that of Bi2MoO6 or Bi2WO6 for the selective oxidation of toluene, with the Bi2W0.3Mo0.7O6 solid solution showing the highest benzaldehyde formation rate (1663 mu mol/(g h)), which was about 1.95 and 2.83 times higher than those obtained over Bi2MoO6 and Bi2WO6, respectively. Furthermore, 91% benzaldehyde selectivity and excellent stability were also achieved over Bi2W0.3Mo0.7O6. The enhancement in photocatalytic activity of Bi2W0.3Mo0.7O6 was attributable to the balance of fast charge kinetics and optimized energy band structure. The results of the reactive species trapping and active radicals detection experiments reveal that the photogenerated holes, superoxide species, and carbon-centered radicals might play the important roles in the generation of benzaldehyde, and the possible photocatalytic toluene oxidation mechanisms over Bi2W0.3Mo0.7O6 were accordingly proposed.
Jang, Jum SukDhandole, Love KumarKoh, Tae SikAnushkkaran, Periyasamy...
11页
查看更多>>摘要：Niobium and zirconium co-doping was introduced into a hematite (Fe2O3) photoanode by a facile two-step synthesis. The hydrothermally prepared zirconium-doped photoanode shows a reduction in the crystallite size of hematite, with H(104) being the dominant photoactive phase. The incorporation of niobium ions by drop -casting and high-temperature annealing does not alter the crystallinity. The core 3d spin-orbit splitting shows the Nb4+ oxidation state forming NbO2 in the hematite lattice. The Nb4+-Zr4+ co-doped hematite photoanode, prepared on a fluorine-tin oxide glass substrate, shows an enhanced photocurrent density of 2.05 mA cm(-2) with no co-catalyst. This enhanced performance is attributed to the Zr4+ doping, which improves the bulk charge transfer in hematite, and Nb4+ suppressed charge recombination in the surface state holes at the electro-de-electrolyte interface. This synergistic improvement of bulk and surface properties leads to stable water splitting at the water oxidation potential (1.23 VRHE) of the Nb-Zr co-doped hematite photoanode.
查看更多>>摘要：Efficient conversion of CO2 is of great significance for sustainable supply of chemicals and fuels. While Co-based catalysts are known to be effective for CO hydrogenation in Fischer-Tropsch synthesis, they work very differently in CO2 hydrogenation. This study reveals a crystallographic dependence of reaction pathways for CO2 hydrogenation on Co catalyst showing a new type of structure sensitivity and structure-activity-selectivity relationship for CO2 conversion to chemicals and fuels. The experimental work on CO2 conversion including steady-state isotopic transient kinetic analysis (SSITKA) using 13C-labeled CO2 shows a preferential CH4 formation over HCP-Co but dominant CO formation over FCC-Co. The density functional theory calculations indicate that CO2 does dissociate directly into chemisorbed CO* and O* on both HCP-Co and FCC-Co, but the CO* intermediates on HCP-Co prefer to be hydrogenated to form CH4 whereas the CO* on FCC-Co preferentially desorb to form CO. The significantly altered adsorption strength of CO* due to the presence of chemisorbed O* and CO2* species on the catalyst surface is responsible for the mechanistic disconnection in product selectivity between the CO2 and CO hydrogenation over Co catalysts. This study also shows that the addition of K to Co diminishes the direct impact of Co crystal structure, but improves the selectivity to C2+ hydrocarbons along with higher CO2 conversion. This seems to result from another pathway originating from HCOO* intermediate from bonding interaction of surface Co atoms with carbon in CO2, leading to the formation of CHx* whose coupling subsequently give rises to C2+ products. The present study sheds new light into the crystallographic structural sensitivity of CO2 hydrogenation towards the rational design of more selective catalysts for CO2 conversion.
Costa-Serge, Nayara de M.Goncalves, Rosembergue G. LimaRamirez-Ubillus, Manuel A.Li, Chan...
12页
查看更多>>摘要：The influence of the interlamellar anion in Layered Double Hydroxide was investigated for the first time in Fenton-like and solar photo-Fenton processes for the degradation of the anticancer drug 5-fluorouracil (5-FU). LDHs of the MgFeCu type were synthesized by coprecipitation with the insertion of CO32-, NO3- , SO42- and B(OH)4- . A strong effect of the interlamellar anion was observed on the catalytic activity with pseudo-first-order rate constant sequence (k): CuMgFe-B(OH)4 > CuMgFe-NO3 > CuMgFe-SO4 > CuMgFe-CO3. Using CuMgFe-B(OH)4, 5-FU was completely degraded under solar radiation after 20 min and after 40 min in the dark, with degradation efficiency maintained above 90% until the fourth cycle of use. It was found that molecular B-O and B-OH interactions induced modifications of the CuMgFe-B(OH)4 surface charge density, accelerating the reduction of Cu (II) and Fe(III), thus favoring reactive oxygen species generation. This performance denotes the excellent potential of CuMgFe-B(OH)4 for 5-FU degradation.
NSTL
Elsevier