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For di-nitroaromatics hydrogenation, it is a challenge to achieve the multi-step hydrogenation with high activity and selectivity due to the complexity of the process involving two nitro groups. Consequently, many precious metal catalysts suffer from low activity for this multi-step hydrogenation reaction. Herein, we employ a fully exposed Pt clusters catalyst consisting of an average of four Pt atoms on nanodiamond@graphene (Ptn/ND@G), demonstrating excellent catalytic performance for the multi-step hydrogenation of 2,4-dinitrotoluene. The TOF (40647 h−1) of Ptn/ND@G is significantly superior to that of single Pt atoms catalyst, Pt nanoparticles catalyst, and even all the known catalysts. Density functional theory calculations and absorption experiments reveal that the synergetic interaction between the multiple active sites of Ptn/ND@G facilitate the co-adsorption/activation of reactants and H2, as well as the desorption of intermediates/products, which is the key for the higher catalytic activity than single Pt atoms catalyst and Pt nanoparticles catalyst. Hydrogenating di-nitroaromatics with high activity and selectivity is challenging due to the process's complexity. Here the authors present a fully exposed Pt clusters catalyst for 2,4-dinitrotoluene hydrogenation, suggesting that the synergy between multiple active sites and moderate adsorption behavior is crucial for the high catalytic activity. [ABSTRACT FROM AUTHOR]

MXene, a two-dimensional (2D) nanomaterial with diverse applications, has gained significant attention due to its 2D lamellar structure, abundance of surface groups, and conductivity. Despite various established synthesis methods since its discovery in 2011, MXenes produced through different approaches exhibit variations in structural and physicochemical characteristics, impacting their suitability for environmental application. This study delves into the effect of synthesis conditions on MXene properties and its adsorption capabilities for four commonly prescribed antibiotics. We utilized material characterization techniques to differentiate MXenes synthesized using three prevalent etchants: hydrofluoric acid (HF), mixed acids (HCl/HF), and fluoride salts (LiF/HCl). Our investigation of adsorption performance included isotherm and kinetic analysis, complemented by density functional theory calculations. The results of this research pinpointed LiF/HCl as an efficient etchant, yielding MXene with favorable morphology and surface chemistry. Electrostatic interactions and hydrogen bonding between MXene surface terminations and ionizable moieties of the antibiotic molecules emerge as pivotal factors in adsorption. Specifically, a higher presence of oxygen terminations increases the binding affinities. These findings provide valuable guidance for etchant selection in environmental applications and underscore the potential to tailor MXenes through synthesis conditions to design membranes capable of selectively removing antibiotics and other targeted substances. [ABSTRACT FROM AUTHOR]

The selective transformation of lignin to value‐added biochemicals (e. g. phenolic acids) in high yields is incredibly challenging due to its structural complexity and many possible reaction pathways. Phenolic acids (PA) are key building blocks for various aromatic polymers, but the isolation of PAs from lignin is below 5 wt.% and requires harsh reaction conditions. Herein, we demonstrate an effective route to selectively convert lignin extracted from sweet sorghum and poplar into isolated PA in a high yield (up to 20 wt.% of lignin) using a low‐cost graphene oxide‐urea hydrogen peroxide (GO‐UHP) catalyst under mild conditions (<120 °C). The lignin conversion yield is up to 95 %, and the remaining low molecular weight organic oils are ready for aviation fuel production to complete lignin utilization. Mechanistic studies demonstrate that pre‐acetylation allows the selective depolymerization of lignin to aromatic aldehydes with a decent yield by GO through the Cα activation of β‐O‐4 cleavage. A urea‐hydrogen peroxide (UHP) oxidative process is followed to transform aldehydes in the depolymerized product to PAs by avoiding the undesired Dakin side reaction due to the electron‐withdrawing effect of the acetyl group. This study opens a new way to selectively cleave lignin side chains to isolated biochemicals under mild conditions. [ABSTRACT FROM AUTHOR]

Metal nanoparticle (NP), cluster and isolated metal atom (or single atom, SA) exhibit different catalytic performance in heterogeneous catalysis originating from their distinct nanostructures. To maximize atom efficiency and boost activity for catalysis, the construction of structure–performance relationship provides an effective way at the atomic level. Here, we successfully fabricate fully exposed Pt3 clusters on the defective nanodiamond@graphene (ND@G) by the assistance of atomically dispersed Sn promoters, and correlated the n-butane direct dehydrogenation (DDH) activity with the average coordination number (CN) of Pt-Pt bond in Pt NP, Pt3 cluster and Pt SA for fundamentally understanding structure (especially the sub-nano structure) effects on n-butane DDH reaction at the atomic level. The as-prepared fully exposed Pt3 cluster catalyst shows higher conversion (35.4%) and remarkable alkene selectivity (99.0%) for n-butane direct DDH reaction at 450 °C, compared to typical Pt NP and Pt SA catalysts supported on ND@G. Density functional theory calculation (DFT) reveal that the fully exposed Pt3 clusters possess favorable dehydrogenation activation barrier of n-butane and reasonable desorption barrier of butene in the DDH reaction. Direct dehydrogenation has been a thematic research area resulting from the energy shortage and petroleum gas upgrading scenario. Here, the authors fabricate fully exposed Pt3 clusters and correlate dehydrogenation activity with average coordination number of Pt-Pt bond. [ABSTRACT FROM AUTHOR]

This study aimed to use a persulfate together with transition metal ions as the reagent to effectively depolymerize lignin into monophenolic compounds under mild conditions (ambient pressure, temperature <100 °C). The Box‐Behnken experimental design in combination with the response surface methodology was applied to obtain optimized reaction conditions. The results showed that this reagent could depolymerize up to 99 % of lignin dimers to mainly veratraldehyde. This reaction also successfully depolymerized industrial lignins with a high yield of phenolic oils and monophenolic compounds. Quantum chemistry calculations using the density functional theory level indicated that the persulfate free radical attacks Cβ to break the β‐O‐4 bond of lignin through a five‐membered ring mechanism. This mechanism using persulfate free radicals has a lower activation barrier than that using hydroxyl radicals. Gel permeation chromatography and 2D‐NMR spectroscopy demonstrated the effective cleavage of the β‐O‐4 bonds of lignin after depolymerization. [ABSTRACT FROM AUTHOR]

Toassess the potential use of O–H stretching modes of aromaticalcohols as ultrafast local probes of transient structures and photoacidity,we analyze the response of the O–H stretching mode in the 2-naphthol-acetonitrile(2N–CH3CN) 1:1 complex after UV photoexcitation.We combine femtosecond UV-infrared pump–probe spectroscopyand a theoretical treatment of vibrational solvatochromic effectsbased on the Pullin perturbative approach, parametrized at the densityfunctional theory (DFT) level. We analyze the effect of hydrogen bondingon the vibrational properties of the photoacid–base complexin the S0state, as compared to O–H stretching vibrationsin a wide range of substituted phenols and naphthols covering the3000–3650 cm–1frequency range. Ground statevibrational properties of these phenols and naphthols with varioussubstituent functional groups are analyzed in solvents of differentpolarity and compared to the vibrational frequency shift of 2N inducedby UV photoexcitation to the 1Lbelectronicexcited state. We find that the O–H stretching frequency shiftsfollow a linear relationship with the solvent polarity function F0= (2ε0– 2)/(2ε0+ 1), where ε0is the static dielectricconstant of the solvent. These changes are directly correlated withphotoacidity trends determined by reported pKavalues and with structural changes in theO···N and O–H hydrogen-bond distances inducedby solvation or photoexcitation of the hydrogen-bonded complexes. [ABSTRACT FROM AUTHOR]

Photocatalytic oxidation of xylose to xylonic acid. [Display omitted] • A hydrothermal method has been reported for the one-step controllable synthesis of efficient and stable ZnS@Bi 2 S 3 nanosheets. • ZnS@Bi 2 S 3 nanosheets photocatalytically efficiently convert monosaccharides into sugar acids. • Provides a new strategy for the oxidation of monosaccharides to the industrialization of sugar acids. Herein, a new hydrothermal method has been reported for one-step controllable synthesis of ZnS@Bi 2 S 3 nanosheets, which were used for the highly selective oxidation of biomass-derived monosaccharides to produce value-added sugar acids. The results of the photocatalytic oxidation by ZnS@Bi 2 S 3 were compared with that by pure Bi 2 S 3, under the same reaction conditions. Compared to pure Bi 2 S 3, ZnS@Bi 2 S 3 nanosheets has showed broadened band gap and improved stability. The relative band alignment indicated that the ZnS@Bi 2 S 3 nanosheets could suppress the recombination of photogenerated charge carriers to improve the photocatalytic activity. Density functional theory (DFT) calculations were performed to investigate the photocatalytic reaction mechanism where xylose and oxygen are adsorbed on Bi 2 S 3 (113) and ZnS (111). The xylose adsorbed on the catalytic surfaces reacted with the active free radicals generated from the photocatalytic process, and then was selectively oxidized to xylonic acid. [ABSTRACT FROM AUTHOR]