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Fully utilizing solar energy for catalysis requires the integration of conversion mechanisms and therefore delicate design of catalyst structures and active species. Herein, a MOF crystal engineering method was developed to controllably synthesize a copper-ceria catalyst with well-dispersed photoactive Cu-[O]-Ce species. Using the preferential oxidation of CO as a model reaction, the catalyst showed remarkably efficient and stable photoactivated catalysis, which found practical application in feed gas treatment for fuel cell gas supply. The coexistence of photochemistry and thermochemistry effects contributes to the high efficiency. Our results demonstrate a catalyst design approach with atomic or molecular precision and a combinatorial photoactivation strategy for solar energy conversion.

Fe-based catalysts have been discovered as the best elementary metal-based heterogeneous catalysts for the ammonia synthesis in industrial application during the last century. Herein, a novel and scalable strategy is developed to prepare the K-promoted Fe/C catalyst with extremely high Fe loading (> 50 wt.%) through pyrolysis of the Fe-based metal-organic framework (MOF) xerogel. The obtained K-Fe/C catalysts exhibited superior activity and stability towards ammonia synthesis. The weight-specific reaction rate of Fe/C with K2O as promoter can achieve 12.4 mmol·g−1·h−1 at 350 °C and 30.4 mmol·g−1·h−1 at 400 °C, approximately four and two times higher than that of the commercial fused-iron catalyst (3.4 mmol·g−1·h−1 at 350 °C and 16.7 mmol·g−1·h−1 at 400 °C) under the same condition, respectively. The excellent performance of K-Fe/C can be ascribed to the inherited structure derived from the metal-organic frame precursors and the promotion of potassium, which can modify the binding energy of reactant molecules on the Fe surface, transfer electrons to iron for effective activation of nitrogen, prevent agglomeration of Fe nanoparticle (NPs) and restrain side reaction of carbon matrix to methane.

It is challenging to effectively convert 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF), a flexible biobased building-block, over non-noble metal catalysts. In this contribution, Mn–Fe oxides were prepared and served as highly active catalysts for the selective oxidation of HMF to DFF. Among Mn–Fe oxides with varied Mn–Fe molar ratios, Mn6Fe1Ox showed the best catalytic activity and offered HMF conversion up to 97% with a DFF selectivity of 98% (110 °C, 5 h, and 1.5 MPa O2). It is revealed that the introduction of α-Fe2O3 resulted in significant enhancement in the amount of catalytic active sites (Mn4+–O2– pairs) and their activity in Mn6Fe1Ox for the dehydrogenation of HMF to DFF. Mn6Fe1Ox also was a robust catalyst that could be successively used at least six times without substantial loss in its catalytic activity. Furthermore, a facile two-step process for the conversion of fructose to DFF with a yield up to 80% was developed by the integration of dehydration and oxidation over Amberlyst-15 ...

We present herein rPTMDetermine, an adaptive and fully automated methodology for validation of the identification of rarely occurring post-translational modifications (PTMs), using a semisupervised approach with a linear discriminant analysis (LDA) algorithm. With this strategy, verification is enhanced through similarity scoring of tandem mass spectrometry (MS/MS) comparisons between modified peptides and their unmodified analogues. We applied rPTMDetermine to (1) perform fully automated validation steps for modified peptides identified from an in silico database and (2) retrieve potential yet-to-be-identified modified peptides from raw data (that had been missed through conventional database searches). In part (1), 99 of 125 3-nitrotyrosyl-containing (nitrated) peptides obtained from a ProteinPilot search were validated and localized. Twenty nitrated peptides were falsely assigned because of incorrect monoisotopic peak assignments, leading to erroneous identification of deamidation and nitration. Five additional nitrated peptides were, however, validated after performing nonmonoisotopic peak correction. In part (2), an additional 236 unique nitrated peptides were retrieved and localized, containing 113 previously unreported nitration sites; 25 endogenous nitrated peptides with novel sites were selected and verified by comparison with synthetic analogues. In summary, we identified and confidently validated 296 unique nitrated peptides-collectively representing the largest number of endogenously identified 3-nitrotyrosyl-containing peptides from the cerebral cortex proteome of a Macaca fascicularis model of stroke. Furthermore, we harnessed the rPTMDetermine strategy to complement conventional database searching and enhance the confidence of assigning rarely occurring PTMs, while recovering many missed peptides. In a final demonstration, we successfully extended the application of rPTMDetermine to peptides featuring tryptophan oxidation.

We report herein the first detailed study of the mechanism of redox reactions occurring during the gas-phase dissociative electron transfer of prototypical ternary [CuII(dien)M]˙2+ complexes (M, peptide). The two final products are (i) the oxidized non-zwitterionic π-centered [M]˙+ species with both the charge and spin densities delocalized over the indole ring of the tryptophan residue and with a C-terminal COOH group intact, and (ii) the complementary ion [CuI(dien)]+. Infrared multiple photon dissociation (IRMPD) action spectroscopy and low-energy collision-induced dissociation (CID) experiments, in conjunction with density functional theory (DFT) calculations, revealed the structural details of the mass-isolated precursor and product cations. Our experimental and theoretical results indicate that the doubly positively charged precursor [CuII(dien)M]˙2+ features electrostatic coordination through the anionic carboxylate end of the zwitterionic M moiety. An additional interaction exists between the indole ring of the tryptophan residue and one of the primary amino groups of the dien ligand; the DFT calculations provided the structures of the precursor ion, intermediates, and products, and enabled us to keep track of the locations of the charge and unpaired electron. The dissociative one-electron transfer reaction is initiated by a gradual transition of the M tripeptide from the zwitterionic form in [CuII(dien)M]˙2+ to the non-zwitterionic M intermediate, through a cascade of conformational changes and proton transfers. In the next step, the highest energy intermediate is formed; here, the copper center is 5-coordinate with coordination from both the carboxylic acid group and the indole ring. A subsequent switch back to 4-coordination to an intermediate IM1, where attachment to GGW occurs through the indole ring only, creates the structure that ultimately undergoes dissociation.

Renewable and sustainable betaine-based catalysts (BX) derived from the betaine sugar industry or ChCl were developed for the production of 5-hydroxymethylfurfural (HMF) from various carbohydrates. The HMF yields in the BX-based media reached up to 88 %, 66 %, 37 % and 53 %, for the conversion of fructose, glucose, cellulose, and lignocellulosic biomass, respectively. In addition, choline-O-sulfate was synthesized and demonstrated to be an efficient catalyst for the conversion of fructose to HMF. From the perspective of green and sustainable chemistry, this work demonstrates benefits not only in the preparation of sustainable catalysts but also the green production of HMF from biomass.

Molecular radical cationic peptides (M +) display rich and diverse gas-phase ion chemistry that can differ substantially from that of their protonated counterparts. Dissociation of M + radical cations can provide relevant structural information for protein sequencing, often complementary to that obtained using traditional approaches. In this study, low-energy collision-induced dissociation (CID) of a series of tyrosine-containing peptide molecular radical cations having an N-terminal phenylalanine residue led to new products resulting from radical-mediated Cα–Cβ bond cleavage at the side chain of the phenylalanine residue. The chemical identity of the species formed through side chain loss (91 Da) occurring via N-terminal Cα–Cβ bond cleavage was examined using a combination of low-energy CID experiments, isotopic labeling mass spectrometric experiments, and density functional theory calculations. This unusual dissociation process occurs with fascinating unimolecular gas phase ion chemistry and requires a π-radical cationic tyrosine residue with significant spin density delocalized into the N-terminal amino group. The radical character at the resulting –NH2 + moiety then induces β-scission at the side chain Cα–Cβ bond of the phenylalanine residue. This discovery also demonstrates the role of the NH2 group in facilitating Cα–Cβ bond cleavage of the phenylalanine residue by the proximal tyrosine π-radical cation, probably involving a through-space electron transfer process.

Up-conversion (UC) oxides comprise a huge family of materials with abundant optical functionalities and they merit extensive research. Some members of this family have been modified with proper rare earth (RE3+) ions and their importance has recently been established in non-contact temperature sensors, although the thermal sensitivity (S) value was still low. In this study, we investigated Nd3+ and Yb3+ sensitized Ba4La2Ti4Nb6O30 (BLTN:xNd3+/Yb3+) with a tungsten bronze structure for use as optical thermometers for the first time. Under excitation at 980 nm, obvious near-infrared emissions corresponding to 4F7/2/4S3/2 → 4I9/2, 4F5/2/2H9/2 → 4I9/2, and 4F3/2 → 4I9/2 transitions were observed, and the UC mechanism involved was elaborated. Furthermore, the UC thermometric properties were investigated according to the fluorescence intensity ratio technique and the maximum S values determined for BLTN:xNd3+/Yb3+ (x = 0.12 and 0.16) samples were both higher than 0.03 K–1. The potential of BLTN:xNd3+/Yb3+ for use in optical thermometers was estimated based on comparisons with other active materials.

The poor solubility of raw cellulose greatly limits its applications. Herein, the periodate oxidation of cellulose was conducted to obtain dialdehyde cellulose (DAC), which is a kind of soluble and...

Summary With the depletion of crude oil and especially the growing demand for lower olefins, the direct conversion of syngas into lower olefins via the Fischer-Tropsch to olefins (FTO) process is a promising alternative for the petroleum route. A photo-driven FTO process can dramatically change the product selectivity over Fe5C2 catalyst, leading to an olefin/paraffin ratio of 10.9 with CO conversion >49%. The selectivity toward CO2 was as low as 18.9%, ensuring a high carbon resource utilization efficiency, and the catalyst showed good stability. Under the photo-irradiation condition, the surface of the Fe5C2 catalyst was spontaneously decorated by O atoms formed in situ, resulting in a high selectivity to olefins, which makes it an excellent catalyst for photo-driven FTO reaction.

Herein, we report the successful application of hybrid Au-Ag nanoparticles (NPs) and nanochains (NCs) in the harvesting of visible light energy for selective hydrogenation reactions. For individual Au@Ag NPs with Au25 cores, the conversion and turnover frequency (TOF) are approximately 8 and 10 times higher than those of Au25 NPs, respectively. Notably, after the self-assembly of the Au@Ag NPs, the conversion and TOF of 1D NCs were approximately 2.5 and 2 times higher than those of isolated Au@Ag NPs, respectively, owing to the coupling of surface plasmon and the increase in the rate at which hot (energetic) electrons are generated with the formation of plasmonic hot spots between NPs. Furthermore, the surface-enhanced Raman scattering (SERS) activity of 1D Au@Ag NCs was strengthened by nearly 2 orders of magnitude.

A series of Er3+- and Yb3+-doped K2LaNb5O15 (KLN:xEr3+/Yb3+) up-conversion (UC) submicro-particles have been synthesized for the first time by a simple and low-cost molten salt (MS) approach. X-ray diffraction (XRD) was performed to analyze the phase and structure, and the prepared KLN:xEr3+/Yb3+ samples exhibited a single phase tetragonal tungsten bronze (TTB) structure. The morphologies were characterized by scanning electron microscopy (SEM), and submicro-rod-like particles were obtained for all samples. Under 980 nm excitation, KLN:xEr3+/Yb3+ emitted bright green and weak red emissions which arose from the intra-4f transitions of Er3+ ions. The UC emission intensities and RR/G (the intensity ratio between red and green emissions) were disclosed to be tightly dependent on the Yb3+ ion concentration, and the involved UC luminescence mechanism was studied. Meanwhile, the slope of log I–log P plots displayed an evident reduction with a Ts (sintering temperature) increase, which was ascribed to the saturation effect coming from the competition between UC processes and linear decay. Furthermore, temperature-dependent UC behavior and temperature sensing properties of KLN:xEr3+/Yb3+ were probed based on the fluorescence intensity ratio (FIR) technique of UC green emission. The maximum sensor sensitivity (S) of KLN:0.04Er3+/Yb3+ (Ts = 900 °C) and KLN:0.16Er3+/Yb3+ (Ts = 900 °C) was determined to be as high as 10.90 × 10−3 and 12.27 × 10−3 K−1, respectively. We also showed that the particle size has an evident influence on S, which can be qualitatively interpreted by J–O theory. Thermal-cycling measurements were conducted at different temperatures, and good reliability and repeatability were confirmed. In addition, an obvious optical heating effect was also realized and the variation of temperature induced with a laser was about 32 K. These results reveal that KLN:xEr3+/Yb3+ submicroparticles with high sensor sensitivity and an obvious laser-induced thermal effect are suitable for future optical thermometers and optical heaters.

Ni catalysts supported on nanosheet (S) and nanoplate (P) γ-Al 2 O 3 have been successfully synthesized for carbon dioxide (CO 2 ) reforming of methane. The Ni/Al 2 O 3 -S catalyst possessed excellent activity and stability whereas the Ni/Al 2 O 3 -P catalyst exhibited slightly lower activity and much worse stability. The Ni/Al 2 O 3 -S catalyst displayed much smaller size of Ni nanoparticles, which may explain the difference in activity. The Ni/Al 2 O 3 -S catalyst possessed enhanced anti-sintering and anti-coke properties, which would lead to an improved stability.

Band gap opening and engineering make up one of the primary goals of developing novel materials for photocatalytic hydrogen generation. We report here a facile synthesis of graphene decorated with in-plane boron nitride domains via control of both the doping sequence of heteroatoms and the oxygen content of the graphene precursor, showing significant differences in the doping pattern compared with B and/or N singly doped or co-doped graphene. We uncover that the formation of BN domains in graphene is critical for engineering the band gap and delivering an improved activity for photocatalytic hydrogen generation in the absence of any photosensitizer. This work paves the way for the rational design and construction of graphene-based photocatalysts for efficient photocatalysis.

Long-range electron transfer in proteins can be rationalized as a sequential short-distance electron-hopping processes via amino acid residues having low ionization energy as relay stations. Tyrosine residues can serve as such redox-active intermediates through one-electron oxidation to form a π-radical cation at its phenol side chain. An electron transfer from a vicinal functional group to this π-electron hole completes an elementary step of charge migration. However, transient oxidized/reduced intermediates formed at those relay stations during electron transfer processes have not been observed. In this study, formation of analog reactive intermediates via electron donor–acceptor coupling is observed by using IRMPD action spectroscopy. An elementary charge migration at the molecular level in model tyrosine-containing peptide radical cations [M]˙+ in the gas phase is revealed with its unusual Cα–Cβ bond cleavage at the side chain of the N-terminal residue. This reaction is induced by the radical character of the N-terminal amino group (–NH2˙+) resulting from an n → π+ interaction between the nonbonding electron pair of NH2 (n) and the π-electron hole at the Tyr side chain (π+). The formation of –NH2˙+ is supported by the IRMPD spectrum showing a characteristic NH2 scissor vibration coupled with Tyr side-chain stretches at 1577 cm−1. This n → π+ interaction facilitates a dissociative electron transfer with NH2 as the relay station. The occurrence of this side-chain cleavage may be an indicator of the formation of reactive conformers featuring the n → π+ interaction.

The economic and highly efficient synthesis of γ-valerolactone (GVL) is being increasingly focused due to its wide applications in solvent, chemical, and fuel. Herein, a range of SAPO-34 supported zirconium phosphate (ZPS-X) catalysts were prepared for a facile one-pot conversion of furfural (FF) to GVL through a series of cascaded reactions involving transfer hydrogenation, etherification, alcoholysis and esterification. The introduction of zirconium phosphate renders the formation of relatively strong Lewis acid sites, and the amount of Lewis (L) and Bronsted (B) acid sites of ZPS-X catalysts could be modified by adjusting the molar ratio of Zr to P (Zr/P ratio). Specifically, ZPS-1.0 having an appropriate Zr/P ratio with relatively strong L acid sites exhibited superior activity and selectivity for the production of GVL from FF.

Transition metal carbide (TMC) nanomaterials are promising alternatives to Pt, and are widely used as heterogeneous electrocatalysts for the electrochemical hydrogen evolution reaction (HER). In this work, a bromide-induced wet-chemistry strategy to synthesize Co2C nanoparticles (NPs) was developed. Such NPs exhibited high electrocatalytic activity (η = 181 mV for j = −10 mA·cm−2) and long-term stability (no obvious performance decrease after 4,000 cycles) for the HER. This study will pave the way for the design and fabrication of TMC NPs via a wet-chemistry method, and will have significant impacts on broader areas such as nanocatalysis and energy conversion.

The CuO nanorods (NRs) are prepared with the help of inositol hexakisphosphate which serves as a binding agent and stabilizer. We have successfully fabricated Cu 2 O-decorated palladium networks (Cu 2 O/Pd Networks) by using such CuO NRs as reaction beds. Transmission electron microscopy images show that Cu 2 O/Pd network is composed of small and irregular fused nanoparticles with an average size of about 10 nm. Electrochemical results depict that the as-synthesized catalyst exhibits 2-fold higher activity for methanol oxidation than the commercially available 20% Pd/C catalyst and Pd black catalyst. Furthermore, CO-tolerance is also remarkably enhanced due to the presence of Cu 2 O. Such highly active, low-cost, and superiorly CO-tolerant catalysts of Cu 2 O/Pd Networks will open up a new avenue for direct methanol fuel cells.

The building blocks of the well-defined and easily modified carbon-bond structure of graphene sheet units bring unique characteristics to carbon materials. Especially when these carbon materials are nanosized, their tunable electronic states, giant conjugated structures, oxygen groups on the defects of graphene sheets, and various dopants all help make the materials active in liquid-phase catalytic reactions. In this mini-review, we mainly focus on the liquid-phase reactions catalyzed by carbon nanomaterials, and the related mechanisms are discussed on the basis of their structure fundamentals. In the final section, we also provide our perspectives on this rapidly developing carbocatalysis field.

Metallic nickel nanostructures that were partially decorated by discrete nickel oxide layers were fabricated by in situ reduction of calcinated Ni-containing layered double hydroxide nanosheets, the structure of which was confirmed by extended X-ray absorption fine structure spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. The existence of the abundant interfaces between the surface Ni oxide overlayer and metallic Ni altered the geometric/electronic structure of the Ni nanoparticles, making them apt for CO activation under light irradiation. Most importantly, the unique structure favors the C-C coupling reaction on its surface, which confers the catalyst unexpected reaction power towards higher hydrocarbons at moderate reaction conditions. This study leads to a green and sustainable approach for the photocatalytic production of highly valuable chemical fuels.

B4C is widely known by a series of unique advantages, such as low density, high hardness, good chemical stability and excellent environmental stability, as a hard ceramic material. However, the study of B4C as the electrode material on micro-electrochemical energy storage devices has not yet been reported. To some extent, the poor conductivity of B4C is an important reason to limit its extensive application in energy storage field. Here, we first report an elaborated design B4C@C of core-shell structure by simple vacuum heating synthesis strategy as electrodes for flexible all-solid-state micro-supercapacitors (MSCs) with the method of mask assisted-vacuum filtration. Notably, the B4C@C-MSCs exhibit outstanding electrochemical performances, such as high areal capacitance of 7.33 mF cm−2, remarkable cycling stability with 100.94% capacitance retention after 50000 cycles, wide operating temperature range (−25 to 75 °C), excellent mechanical flexibility without obviously performance degradation under different bending states, distinguished environmental stability and superior integration. These results suggest that the hard ceramic materials B4C have a promising prospect in micro-electrochemical energy storage devices.

Conversion of syngas (CO, H2 ) to hydrocarbons, commonly known as the Fischer-Tropsch (FT) synthesis, represents a fundamental pillar in today's chemical industry and is typically carried out under technically demanding conditions (1-3 MPa, 300-400 °C). Photocatalysis using sunlight offers an alternative and potentially more sustainable approach for the transformation of small molecules (H2 O, CO, CO2 , N2 , etc.) to high-valuable products, including hydrocarbons. Herein, a novel series of Fe-based heterostructured photocatalysts (Fe-x) is successfully fabricated via H2 reduction of ZnFeAl-layered double hydroxide (LDH) nanosheets at temperatures (x) in the range 300-650 °C. At a reduction temperature of 500 °C, the heterostructured photocatalyst formed (Fe-500) consists of Fe0 and FeOx nanoparticles supported by ZnO and amorphous Al2 O3 . Fe-500 demonstrates remarkable CO hydrogenation performance with very high initial selectivities toward hydrocarbons (89%) and especially light olefins (42%), and a very low selectivity towards CO2 (11%). The intimate and abundant interfacial contacts between metallic Fe0 and FeOx in the Fe-500 photocatalyst underpins its outstanding photocatalytic performance. The photocatalytic production of high-value light olefins with suppressed CO2 selectivity from CO hydrogenation is demonstrated here.

A one-step ligand-free method based on an adsorption-precipitation process was developed to fabricate iridium/cerium oxide (Ir/CeO2 ) nanocatalysts. Ir species demonstrated a strong metal-support interaction (SMSI) with the CeO2 substrate. The chemical state of Ir could be finely tuned by altering the loading of the metal. In the carbon dioxide (CO2 ) hydrogenation reaction it was shown that the chemical state of Ir species-induced by a SMSI-has a major impact on the reaction selectivity. Direct evidence is provided indicating that a single-site catalyst is not a prerequisite for inhibition of methanation and sole production of carbon monoxide (CO) in CO2 hydrogenation. Instead, modulation of the chemical state of metal species by a strong metal-support interaction is more important for regulation of the observed selectivity (metallic Ir particles select for methane while partially oxidized Ir species select for CO production). The study provides insight into heterogeneous catalysts at nano, sub-nano, and atomic scales.

Zn- and Na-modulated Fe catalysts were fabricated by a simple coprecipitation/washing method. Zn greatly changed the size of iron species, serving as the structural promoter, while the existence of Na on the surface of the Fe catalyst alters the electronic structure, making the catalyst very active for CO activation. Most importantly, the electronic structure of the catalyst surface suppresses the hydrogenation of double bonds and promotes desorption of products, which renders the catalyst unexpectedly reactive toward alkenes-especially C5+ alkenes (with more than 50% selectivity in hydrocarbons)-while lowering the selectivity for undesired products. This study enriches C1 chemistry and the design of highly selective new catalysts for high-value chemicals.

Naked magnetically recyclable mesoporous Au–γ-Fe2O3 clusters, combining the inherent magnetic properties of γ-Fe2O3 and the high catalytic activity of Au nanoparticles (NPs), are successfully synthesized. Hydrophobic Au–Fe3O4 dimers are first self-assembled to form sub-micrometer-sized Au–Fe3O4 clusters. The Au–Fe3O4 clusters are then coated with silica, calcined at 550 °C, and finally alkali treated to dissolve the silica shell, yielding naked-Au–γ-Fe2O3 clusters containing Au NPs of size 5–8 nm. The silica protection strategy serves to preserve the mesoporous structure of the clusters, inhibit the phase transformation from γ-Fe2O3 to α-Fe2O3, and prevent cluster aggregation during the synthesis. For the reduction of p-nitrophenol by NaBH4, the activity of the naked-Au–γ-Fe2O3 clusters is ≈22 times higher than that of self-assembled Au–Fe3O4 clusters. Moreover, the naked-Au–γ-Fe2O3 clusters display vastly superior activity for CO oxidation compared with carbon-supported Au–γ-Fe2O3 dimers, due to the intimate interfacial contact between Au and γ-Fe2O3 in the clusters. Following reaction, the naked-Au–γ-Fe2O3 clusters can easily be recovered magnetically and reused in different applications, adding to their versatility. Results suggest that naked-Au–γ-Fe2O3 clusters are a very promising catalytic platform affording high activity. The strategy developed here can easily be adapted to other metal NP–iron oxide systems.