查看更多>>摘要：Covalent organic frameworks linked by C=C bonds have gained great attention for various application, and their fully conjugated skeletons were potentially conversed into two-dimensional (2D) carbons. Herein, we described a novel strategy to fabricate 2D carbon nanorods from a sp(2) carbon linked COF, which had a high surface area of 804.8 m(2) g(-1). The one-dimensional channels confined the Fe ions during pyrolysis, which facilitated to form ultra-close atomic sites. The resulting catalyst displayed high catalytic activity towards oxygen reduction reaction, with a half-wave potential of 0.82 V and a mass activity of 4087.9 mA mg(-1) at 0.7 V versus RHE, which were high than those of Pt/C (0.81 V and 126.3 mA mg(-1)). The theoretical calculation revealed the close FeN4 sites achieved a lower *OH adsorption energy than isolated FeN4 sites. This work provides a new insight into developing single atom catalysts from COFs.
Azancot, LolaBlay, VincentBlay-Roger, RubenBobadilla, Luis F....
13页
查看更多>>摘要：Liquid fuels produced via Fischer-Tropsch synthesis from biomass-derived syngas constitute an attractive and sustainable energy vector for the transportation sector. This study focuses on the role of potassium as a promoter in Ni-based catalysts for reducing coke deposition during catalytic dry reforming. The study provides a new structural link between catalytic performance and physicochemical properties. We identify new Ni-O-K chemical states associated with high stability in the reforming process, evidenced by different characterization techniques. The nickel particles form a core surrounded by a Ni-O-K phase layer (Ni@Ni-O-K) during the reduction of the catalyst. This phase likely presents an alkali-nickelate-type structure, in which nickel is stabilized in oxidation state + 3. The Ni-O-K formation induces essential changes in the electronic, physical, structural, and morphological properties of the catalysts, notably enhancing their long-term stability in dry reforming. This work thus provides new directions for designing more efficient catalysts for sustainable gas-to-liquids processes.
查看更多>>摘要：In this work, an efficient wide solar light-driven photocatalyst based on solar UV-blind beta-Ga2O3 quadrilateral nanorods (beta-GOR) has been modified with cobalt phthalocyanine (CoPc). Guided by density functional theory (DFT) calculations and experimental results, H-bond strengthened interfacial connection was established to purchase wide range of solar radiations and applied as an efficient photocatalysts for H-2 evolution from water. The optimized 3CoPc/beta-GOR nanocomposite unveiled an unprecedented in the quantum efficiency (0.38%) at 660 nm excitation wavelength with outstanding structural stability compare to the pristine solar UV-blind beta-GOR (0%). The much extended photoactivities are accredited to the formation of strong H-bond between CoPc and beta-GOR, that accelerated charge transformation as confirmed from Bader charge/work function analysis, activation of O2, wide visible-light absorption, as well as joint DFT and experimental results. We believe that this system will also work for other metal phthalocyanines such as ZnPc, NiPc and HPc together with beta-GOR towards next-generation efficient photocatalysts with wide-visible light response.
查看更多>>摘要：Transition metal-based pre-catalysts undergo drastic reconstruction to form the active catalysts during the alkaline oxygen evolution reaction (OER). However, the effect of escaped inactive ion from pre-catalysts themselves is usually ignored during reconstruction processes. Here, we investigate the effect of inactive MoO(4)(2-& nbsp;)escaped from a pre-catalyst of Fe incorporated nickel-molybdenum oxyhydroxide (NiMo-Fe) on OER performance. The results of in-situ Raman and X-ray photoelectron spectroscopy reveal that MoO(4)(2-& nbsp;)can be easily dissolved into KOH electrolyte and re-adsorbed on surface of catalyst during OER processes, which delivers a promoting effect on OER performance. The dissolution of MoO(4)(2-& nbsp;)is beneficial for increasing the reconstruction degree of NiMo-Fe to form the active phase of NiFeOOH. Theoretical calculations demonstrate that the re adsorbed MoO(4)(2-& nbsp;)is favorable for the adsorption of the OOH* intermediate, thus boosts the OER activity. As expected, the NiMo-Fe shows a superior electrocatalytic performance for OER, outperforming the pre-catalyst without Mo species. This finding enriches the knowledge of inactive-ion effect on alkaline OER performance and offers a path for developing efficient electrocatalysts.
查看更多>>摘要：Electrocatalytic overall water splitting (OWS) to produce hydrogen and oxygen is one of the most advantageous ways to match the carbon-neutral concept in sustainable hydrogen production. Herein, we report a novel non-precious metal bifunctional electrocatalyst, chiral macromolecular metal-organic frameworks with lattice strain on nickel foam (LS-CMMOFs/NF), by replacing disulfonic acid with mono-sulfonic acid for effective and controlled introduction of lattice strain. Under alkaline conditions, LS-CMMOFs/NF at 6% lattice expansion (6% LS-CMMOFs/NF) have the best catalytic performances for oxygen evolution reaction (OER), hydrogen evolution reaction (HER) and OWS, the activity of the catalyst is significantly improved compared with that of the original CMMOFs/NF (O-CMMOFs/NF). The 6%LS-CMMOFs/NF deliver tiny overpotentials of 100 mV (HER), 137 mV (OER), total voltages of 1.467 V (OWS) at 10 mA cm(-2) and maintain100-hours excellent stability. Noteworthy, the OER can reach 500 mA cm(-2), with promising industrial applications. Catalytic mechanism studies, such as operando Raman, operando FTIR and density functional theory calculations indicate that lattice strain effectively enables electrons to pass through Ni/Co 3d-O 2p-Fe 3d more rapidly, thus optimizing metal 3d orbitals, which in turn activates the active surface species (Ni/Co-OOH for OER and Ni/Co-N for HER) and ultimately increases the electrocatalytic activity.
查看更多>>摘要：In this study, a flat and uniform polycrystalline Cu3BiS3 (CBS) thin film was prepared on a molybdenum-coated glass (Mo-SLG) by spray pyrolysis deposition for generation of hydrogen peroxide (H2O2). The dense structure of the film promoted charge transmission, and the combination of the p-type CBS and n-type semiconductor In2S3 deposited by the chemical bath method improved the electron-hole separation efficiency, resulting in a significantly enhanced photocurrent. Deposition of Au nanoparticles reduced the required free energy for oxygen reduction reaction (ORR), improving the selectivity from O-2 to H2O2. The photoelectrochemical (PEC) synthesis proceeds by an indirect 2e(-) ORR initial formation of superoxide, which is disproportionated to H2O2. In the presence of oxygen and visible light, Au-In2S3/CBS could be used to synthesize H2O2 (5.5 mg.L-1.h(-1).cm(-1)) with good Faraday efficiency (71%). This study provided a practical strategy for designing a highly efficient photocathode to produce H2O2 based on improvement in electron-hole transmission efficiency and product selectivity.
查看更多>>摘要：BiOI/BiP5O14 heterostructure with enhanced interfacial internal electric field for directional charge transfer and separation effectively were constructed successfully through epitaxial BiP5O14 layer on the surface of BiOI nanosheets. Dramatical enhanced internal electric field of BiOI/BiP5O14 heterostructure was established when BiP5O14 monolayer epitaxial grow on the surface of BiOI nanosheets by adding 2% of NaH2PO4. As a result, this heterostructure could boost the photodegradation and mineralization of phenol. Compared to pristine BiOI nanosheets, the photocatalytic reaction constant rates of phenol over the BiOI/BiP5O14 heterostructure were elevated over 8.5 times, and the corresponding mineralization ability was also enhanced 8.9 times due to the effective and directional charges transfer and separation. This work provides an evidential proof of rational designing heterostructure via epitaxial growth, and confirms the internal electric field drive charge transfer and separation directionally for promoted photocatalytic performances.
查看更多>>摘要：Developing single-atom photocatalysts for selective conversion of CO2 to valuable fuel is of great attraction but remains challenging. In this work, ruthenium and copper single atoms are for the first time simultaneously incorporated into polymeric carbon nitride (PCN) through a simple preassembly-coprecipitation-pyrolysis process. The obtained PCN-RuCu sample exhibited much higher selectivity (95%) for CH4 production than the individual Ru or Cu decorated PCN during photocatalytic CO2 reduction under visible-light irradiation. The atomically dispersed Ru-N4 and Cu-N3 moieties were confirmed by spherical aberration-corrected electron microscopy and extended X-ray absorption fine structure spectroscopy. Density function theory (DFT) calculations revealed that the co-existence of Ru-N4 sites and Cu-N3 sites can effectively tune the electronic structure of PCN, making the Ru sites account for photogenerated electron-hole pairs and the Cu sites for CO2 hydrogenation. Moreover, the synergetic effect between Ru and Cu single atoms significantly promotes the consecutive hydrogenation processes of *CO species towards CH4 production. Our studies provide a new understanding of the mechanism for photocatalytic reduction of CO2 to CH4, and pave a new way to design photocatalysts for the selective production of solar fuels.
查看更多>>摘要：Tunable synthesis of higher alcohols or formyl compounds (aldehydes and ketones) from syngas is attractive. However, precise control of the coordination between CO dissociative and CO non-dissociative sites, for inactive hydrogenation into aldehyde and ketone are still challenging. Herein, we realized a record-breaking oxygenate selectivity of similar to 70 wt% in organics at a mild temperature of 170 degrees C on the K-Fe catalysts, 88% of which is formyl compounds, ranking the highest among the related catalysts. A high selectivity of alcohols of 40.7 wt% is also observed on the Fe catalyst without modification. It is found that K promoter can adjust surface chemical environment (C-rich and H-lean surface) and reaction intermediates, furthermore, can prompt the CO non-dissociative sites from Fe2C to Fe for alcohol to formyl compound shift. This study provides an alternative strategy to adjust the interaction among active phases and impact on reactant activation to tune the different product distribution.
查看更多>>摘要：2D-layered metallic molybdenum disulfide i.e. 1T MoS2 possess prominent electronic conductivity and abundant electrochemically active sites. However, tuning its metastable crystal structure for promoting catalytic performance is a big technical challenge. Here, we reveal the role of the intercalated reducible-NH and-NH2 species as structural stabilizers in supporting the lamellar structure of 1T MoS2, and then propose a novel H2O2-cleaning strategy to reduce the amount of reducible-NH and-NH2 species for modulating the crystallinity and layer thickness of 1T MoS(2 & nbsp;)without degrading to 2H MoS2. The resultant pseudo-1T MoS2 exhibits larger specific surface area (up by 1.6 times) and higher electron mobility compared to original 1T MoS2, leading to excellent photo/electrocatalytic HER activity. Impressively, pseudo-1T MoS2 achieves high visible-light-driven photo-catalytic HER rate of 235.0 mmol.h(-1).g(-1) in combination with CdS. This work offers an extendable crystal structural fine-tuning approach to promote the catalytic activity of metallic transition metal dichalcogenides.
NSTL
Elsevier