Polycaprolactone emerges as a significant alternative to non-degradable plastics as the enhancing substantial environmental stress from the plastic products consumption. epsilon-Caprolactone (epsilon-CL), as its monomer, has attracted enormous attention. The Baeyer-Villiger (B-V) oxidation serves as an efficient method to produce lactones and esters from carbonyl compounds. In this study, an efficient functionalized metal-organic frameworks (HKUST-1) is applied to the B-V oxidation of cyclohexanone (Cy=O) to produce epsilon-caprolactone (epsilon-CL) under atmospheric pressure, utilizing molecular oxygen as the oxidant and benzaldehyde as the co-oxidant. The HKUST-1 featuring unsaturated metal centers, achieved via the removal of labile ligand solvent molecules, offer promising platforms for catalysis. And the electronegative groups are introduced to fine-tune the electronic states of the HKUST-1 through the distal microenvironment modification around coordinatively unsaturated sites (CUS). The experimental results indicated that Br-HKUST-1 achieves a 78.26 % conversion rate of Cy=O and a 94.83 % selectivity towards epsilon-CL. Furthermore, the yield of epsilon-CL remains stable at 70 % after five catalytic cycles. These findings provide a new strategy for designing catalysts suitable for the B-V oxidation of Cy=O and expound the influence of location-specific distal microenvironment modification on the catalysis.

Light olefins are a significant building block of the modern chemical industry. The predominant technology for producing light olefins is the steam cracking of naphtha. Despite extensive optimization over the years, this process remains highly energy and carbon intensive. Oxidative cracking has emerged as a promising approach to mitigate these energy and carbon intensities by integrating catalytic oxidation with cracking reactions. However, this process is hindered by the co-feeding of oxygen, which leads to substantial COX formation and raises safety concerns. In this study, we developed a redox oxidative cracking (ROC) process as an alternative strategy for naphtha conversion. We investigated the influence of A2WO4 (where A = Li, Na, K, and Cs) on CaMnO3-based redox catalysts in the oxidative cracking of naphtha, utilizing cyclohexane as a representative model compound. The ROC process successfully achieved the conversion of cyclohexane in an auto-thermal and cyclic redox mode facilitated by CaMnO3-based redox catalysts. Notably, the 20% Na-W/CM catalyst exhibited significantly higher olefins yields (up to 57.77 %) at 750 degrees C and a space velocity of 6000 h-1, resulting in a 35 % yield enhancement compared to traditional O2-cofeed oxidative cracking and more than threefold increase over thermal cracking. This performance enhancement arises from the role of Na2WO4 as a surface modifier that modulates the migration rate and evolution direction of lattice oxygen in CaMnO3, thereby promoting selective hydrogen combustion under redox conditions. These findings underscore the importance of modifying alkali metal oxide promoters and provide valuable insights for the design and optimization of redox catalysts in ROC reactions.

High-entropy alloys (HEAs) show great promise for the hydrogen evolution reaction (HER) due to their tunable electronic structures and strong structural stability. However, most reported HEAs rely on kinetically stabilized structures, which limit the regulation of atomic and electronic structures in HEAs. In this work, a thermodynamically stabilized and driven synthesis method was employed to synthesize HEAs containing 5-15 elements. Structural characterization reveals that all samples adopt a single-phase solid solution structure, with the HEA nanoparticles (NPs) uniformly dispersed on the carbon support surface. Electrochemical tests showed that the catalytic performance of HEAs with the same elements in the HER can be tuned easily by adjusting the parameters in thermal synthesis. This provides a promising and practical pathway toward achieving "infinite" catalytic performance with "finite" metal elements. Furthermore, HEA NPs containing more than 15 types of elements can also be easily prepared. Using the HER as a model reaction, the HER catalytic activity shows regular changes with heat-treatment temperature, heat-treatment time and the number of constituent elements, indicating that the atomic coordination structure, electronic energy levels, etc., in HEAs can be continuously tuned through heat treatment synthesis parameters. For HEAs synthesized via thermodynamic routes with simple elemental mixing, the minimum overpotential for the HER can reach 32 mV, demonstrating that the thermodynamically stability-driven HEA strategy features convenience and universality in HEA synthesis and activity regulation.

Solar interface distillation is a promising solution to global freshwater scarcity but is severely limited by inefficient semi-volatile organic compound (s-VOC) removal. Herein, we developed a synergistic photothermal-photocatalytic Fenton system based on Prussian blue/titanium dioxide/silicon dioxide nanofibers (PB/TiO2/SiO2 NFs) to address this bottleneck, enhancing both model s-VOC degradation and salt removal. Anchoring PB nanoparticles (NPs) on TiO2/SiO2 NFs maximizes catalytic active site exposure and ensures structural stability under harsh high-temperature/corrosive conditions. Under 1 kW/m2 illumination, the system achieves a distillation rate of 1.29 kg/m2·h. At 4 kW/m2, solar-to-steam efficiency reaches 80.14%. In addition, PB's Fenton reaction and TiO2's photocatalysis synergistically drive >90% degradation of model pollutant aniline and > 90% inorganic salt removal. Based on density functional theory (DFT) analysis, the use of Fukui functions and intermediate product analysis to predict the degradation pathways of phenylamine molecules, it was inferred that during the degradation of phenylamine by PB/TiO2/SiO2 NFs, the attack begins with “frontal benzene ring and the -NH2+”, and utilizes H2O2 to initiate electrophilic reactions between phenylamine and ·OH and ·O2−, and two degradation pathways occur during this process. Ultimately, phenylamine is broken down into inorganic products. In addition, in this study, the in-situ degradation mechanism of PB/TiO2/SiO2 NFs was determined through mass balance analysis, and the synergistic mechanism of evaporation, catalysis and degradation of the reactor was expounded. This multi-mechanism synergistic material offers a cost-effective, eco-friendly, biosafe solution for s-VOC-polluted water, providing an innovative dual-effect approach to address the issues of freshwater shortage and water pollution.

Electrochemical urea electrolysis has merged as a promising alternative to conventional water splitting methods for hydrogen fuel production due to its cost-effectiveness and superior energy efficiency. The utilization of heterostructures has been proposed as a viable strategy to improve the efficiency of the urea oxidation reaction (UOR) by augmenting the quantity of active sites and optimizing the electronic structure. In this study, a Ni (OH)(2)/NiOOH heterojunction, referred to as H-Ni, was synthesized via a straightforward hydrothermal synthesis method. The notable performance of H-Ni in UOR is ascribed to the synergistic interaction between Ni(OH)(2) and NiOOH, which constitute the principal components of the catalyst. Density functional theory (DFT) calculations reveal that the H-Ni composite is capable of modulating the d-band center, thereby enhancing the adsorption and desorption of reaction intermediates and decreasing the Gibbs free energy (Delta G) associated with the rate-determining step (RDS) of the UOR. Experimental results from catalytic performance tests indicate that the HNi-140 catalyst attains a current density of 10 mA.cm(-2) in a 1.0 M KOH electrolyte containing 0.33 M urea at a relatively low potential of 1.341 V versus reversible hydrogen electrode (RHE), thereby highlighting its superior electrocatalytic performance. Furthermore, the catalyst requires only a cell voltage of 1.78 V to achieve a current density of 100 mA.cm(-2), which is approximately 120 mV lower than that required for water electrolysis. This work presents a straightforward methodology for the cost-effective development of heterojunction catalysts.

Electrochemical reduction of carbon dioxide to value-added chemical feedstocks and fuels presents a promising strategy for carbon utilization and storage. Although advancements in enhancing the selectivity for C1 and C2 products have been witnessed, the research progress for efficient production of C3+ molecules remains slow. Moreover, the mechanism underlying carbon chain growth is still ambiguous. In this review, the recent developments in understanding how C-C coupling proceeds in the pathway toward C3+ molecules are mainly focused on. A few examples which reported the formation of C3-C6 molecules in electroreduction of carbon dioxide are first elaborated. Then, the production of 1-propanol, 2-propanol, 1-butanol, allyl alcohol, and propylene, with particular attention to the mechanism of carbon chain growth, is consecutively discussed. Moreover, alternatives for synthesizing valuable C3+ molecules from carbon dioxide, including tandem electrolyzer and electro-bio hybrid systems, are explored. The review is concluded with remarks on current challenges as well as perspectives on future research possibilities in electroreduction of carbon dioxide to C3+ chemicals and fuels.

In chemistry, a cluster refers to an ensemble of a certain number of atoms that exhibit distinct physicochemical properties as a unified entity. Isostructural clusters, with subtle variations in structure or composition, can display opposite charges, behaving like monatomic ions to undergo classical reaction processes like disproportionation. Herein, we report that the semiconductor nanoclusters can be obtained in the form of a co-crystallized ionic pair, [Cu56S12(SAdm)20(PP)10]+[S@Cu56S12(SAdm)20(PP)10]- (abbreviated as [S-Cu56]·[S@S-Cu56] hereafter). This bi-nanocluster system is a derivative of a neutral copper sulfide nanocluster [S-Cu56] with an interesting onion-like structural configuration containing multiple shells. It consists of two nearly isostructural copper sulfide nanoclusters with opposite charges that differ only by the presence of a S2- ion at the center of the cluster assembly. This represents an interesting ionic bi-nanocluster system within the p-type copper sulfide semiconductor family, offering the potential to exhibit electrical properties not observed in the individual component nanoclusters. Notably, by utilizing different chiral carboxylate ligands, chirality can be concurrently imparted to the inorganic cores of both ionic clusters, thereby enabling distinct chiroptical responses as revealed by circular dichroism spectroscopy. This eventually results in four different structural configurations based on this onion-like semiconductor nanocluster platform.

The utilization of sustainable lignocellulosic biomass for the production of high-value products could potentially solve the intensive reliance on fossil fuels. 2,5-furandicarboxylic acid (FDCA), obtained from 5-hydroxymethylfurfural (HMF) oxidation, is a significant precursor for biomass converted high-value chemicals. Nowadays, the rational design of pre-catalysts via electrochemical self-reconstruction provides an opportunity to design efficient catalysts for electrooxidation process. In this study, we developed a pre-catalyst consisting of nanoscale cubic NiFePBA anchored on Ni(OH)2. After electrochemical reconstruction, it demonstrated superior HMF oxidation reaction (HMFOR) performance. The results demonstrate that the electrochemical self-reconstruction process converts nanoscale cubic NiFePBA into nanosheeted metal oxyhydroxide, resulting in the formation of an oxygen defect-rich heterostructure with Ni(OH)2. This reconstruction process also enhance the electrochemically active surface area, thereby increasing the number of active sites. The combined effect of increased active sites and oxygen defects significantly enhances the HMF adsorption and the HMFOR activity. In situ electrochemical impedance spectroscopy further reveals that the reconstructed NiFePBA/Ni(OH)2-R exhibits accelerated reaction kinetics and reduced reaction potential during the electrocatalytic oxidation of HMF. The NiFePBA/Ni(OH)2-R catalyst exhibited exceptional electrochemical performance, achieving a high current density of 50 mA & sdot;cm-2 at a relatively low potential of 1.43 V vs. RHE. This performance is characterized by a remarkable 99.1 % conversion of HMF, 98.5 % selectivity for FDCA, and a Faradaic efficiency of 94.2 %. This study offers valuable insights for the development of high-performance HMFOR electrocatalysts.

The selective oxidation of cyclohexane to cyclohexanone and cyclohexanol (KA oil) is a challenging issue in the chemical industry. At present the industrial conversion of cyclohexane to cyclohexanone and cyclohexanol is normally controlled at less than 5% selectivity. Thus, the development of highly active and stable catalysts for the aerobic oxidation of cyclohexane is necessary to overcome this low-efficiency process. Therefore, we have developed a cobalt-nitrogen co-doped porous sphere catalyst, Co-NC- x ( x is the Zn/Co molar ratio, where x = 0, 0.5, 1, 2, and 4) by pyrolyzing resorcinol-formaldehyde resin microspheres. It achieved 88.28% cyclohexanone and cyclohexanol selectivity and a cyclohexane conversion of 8.88% under Co-NC-2. The results showed that the introduction of zinc effectively alleviated the aggregation of Co nanoparticles and optimized the structural properties of the material. In addition, Co 0 and pyridinic-N are proposed to be the possible active species, and their proportion efficiently increased in the presence of Zn 2+ species. In this study, we developed a novel strategy to design highly active catalysts for cyclohexane oxidation.

The local environment of active sites is a key focus in the field of redox chemistry research. Here, the manipulation of lattice oxygen in La0.8Sr0.2Fe0.8M0.2O3 facilitates the chemical looping redox oxidative cracking (CL-ROC) process. Among the samples, La0.8Sr0.2Fe0.8Cu0.2O3 exhibits exceptional olefin yield (61.74 %) in the cyclohexane CL-ROC reaction. The integration of experiments and density theory calculations shows that the introduction of foreign redox-inert cations into the B-sites of the matrix can effectively alter the configuration of FeO6, improve the activation of lattice oxygen, and enhance the activity of surface oxygen and the mobility of bulk lattice oxygen. Furthermore, the improvement in olefin selectivity is closely linked to the suppression of peroxide products formation, a result of increased oxygen vacancy and decreased bulk lattice oxygen. These findings exemplify the feasibility to manipulate the activity of lattice oxygen in perovskite oxides by adjusting the distortion of the BO6 in ABO(3) perovskite structures.

Metal-free catalysts without metal active sites participating in the reactions have obtained growing attraction under the drive of the economic and environmental problems. Here, 2D-COFs-drived B/N co-doped carbon nanosheets as metal-free catalyst was synthesized by Schiff-based coupling reaction and self-templated carbonization. It shows excellent catalytic performance in nitro compound hydrogenation reaction as all-solid FLP catalyst in H2 system (100 % conversion of nitrobenzene and 99.89 % selectivity to aniline) without any metal active species in the catalyst. This result is the most promising compared to the previous literatures. In the study, the high crystallinity of precursor 2D-COFs is imperative for catalytic stability, and the function of B atoms modification and the B-N synergism were investigated carefully. The formation of B-N bond as a fixed all-solid FLP active center was verified, and it also indicates that B atoms introduction can make the carbon nanosheets orderly and enhance the strength and amount of the acid and base sites. The catalytic mechanism of hydrogen activation was also studied by combining the characterization results and density functional theory (DFT) calculations. The results show that the B atoms doping and defects formation efficiently accelerate the charges aggregation between B-N bonds to form Lewis pairs, and the TS searching calculations shows the significant decrease of H2 dissociation barrier energy and the reaction energy, demonstrating the effectiveness of N and B co-doping strategy. This work is very promising and the metal-free catalyst is the potential alternative to traditional metal catalysts.

Zeolitic imidazolate frameworks (ZIFs) were prepared by different methods for the chemoselective hydrogenation of biomass-derived cinnamaldehyde. It was found that the ZIFs prepared by microwave-assisted method (ZIF-67-MW) shows more defects, and the independent Lewis acid (metal center) and Lewis basic (N in 2-methylimidazole) sites in the defective ZIFs construct a heterogeneous Frustrated Lewis pairs (FLPs) system. The theoretical calculations indicate that the FLPs sites in the defec-tive ZIFs can easily dissociate the H-H bond with a low activation energy of 8.7 kcal/mol. And the silica-coated and hydrophobically modified core-shell structure of ZIF-67-MW@SiO2-DMDES is developed to enhance the stability of ZIF-67-MW and the selectivity to cinnamyl alcohol, it gives > 99% cinnamalde-hyde conversion and 95.3% selectivity to cinnamyl alcohol. Furthermore, the reaction mechanism was proposed by the combination of experimental results and theoretical calculations. The results of substrate-extending experiments show that ZIF-67-MW@SiO2-DMDES presents brighter prospects in the selective hydrogenation of a series of unsaturated aldehydes.(c) 2023 Elsevier Inc. All rights reserved.

Metal-free catalysts for hydrogenation reactions using molecular hydrogen (H2) are a major challenge in the field of catalysis. The Frustrated Lewis Pairs (FLPs) systems and heteroatom-doped carbon materials as metal-free catalysts are currently the mainstream research in hydrogenation reactions. Here, a series of oxygen-induced zigzag graphene (OZG) was constructed over thermal treatment of reduced graphene oxide (rGO) and applied as metal-free catalysts in nitrobenzene hydrogenation. The OZG-800 (thermal treatment at 800 degrees C) shows promising performance activity with 99.7% nitrobenzene conversion and 94.4% selectivity to aniline. The experimental results indicate that the zigzag edge and medium-strong acid sites formed by oxygen species may be the active centers in nitrobenzene hydrogenation. The density functional theory (DFT) calculations are in accord with experimental results that the zigzag edge and oxygen species play a critical role in H2 activation and dissociation. This work provides a promising route for the rational design of metal-free catalysts for hydrogenation.

Polycaprolactone is a significant alternative to nondegradable plastic, and the synthesis of its monomer e-caprolactone (e-CL) has obtained increasing attention. Here, one kind of Cu-SiO2 bifunctional catalyst with highly dispersed copper species and various metal valences was developed and applied in Baeyer - Villiger (B-V) oxidation for cyclohexanone (Cy=O) to produce e-CL with O2/benzaldehyde. The Lewis acidity and the different valence of the copper species could be adjusted by two simple post-treatment methods. The optimal Cu-SiO2-601.5 exhibits > 99 % conversion of Cy=O and > 99 % selectivity to e-CL with high efficiency of BEA. The enhancement primarily originates from the synergism of Cu2+, Cu+, and the Lewis acidity of the catalysts. In addition, the possible mechanisms and realistic reaction path were proposed and verified by combing the characterization and DFT calculations. It clarifies the not well-understood reaction mechanism in B-V oxidation of Cy=O. And it reveals that the formation of the Ph-CO3H intermediate is rate-limiting step, and it is beneficial for the vital "Criegee" intermediates formation thanks to its lower activation energy. This work provides a promising strategy for designing suitable oxidative catalysts and clarifies realistic reaction path of B-V oxidation of Cy=O, which could improve the development of degradable plastics.

In this work, MOF-derived Ni@C catalysts with rich defects were synthesized using a facile thermally decarbox-ylation-induced defect strategy for nitrocyclohexane (NCH) hydrogenation. It was found that the strong metal-support interaction (SMSI) between the defect-rich carbon and Ni promotes the dispersion of Ni nanoparticles, reduces the Ni particle size, and affects the surface charge state of Ni to form electron-deficient Ni, thus exhibiting outstanding catalytic activity. Additionally, in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) illustrates that the transformation path of nitrosocyclohexane (N-NCH) is critical for obtaining high selectivity to cyclohexanone oxime (CHO). Furthermore, the density functional theory (DFT) calculations confirm that the SMSI between the defect-rich carbon and Ni leads to the formation of electron-deficient Ni with a lower d-band center, which can weaken the adsorption of N-NCH and CHO, enhance the adsorption of N-cyclohexylhydroxylamine (N-CHH) and cyclohexylamine (CHA), reduce the reaction energy of the N-NCH to CHO, and increase the reaction energy of the N-NCH to CHA, thus showing the highest selectivity to CHO. Under optimum conditions, Ni@DC-0.06 gives 97.2% selectivity to CHO at 95.2% NCH conversion.

Photocatalytic hydrogen evolution is a promising technology for alleviating energy and environmental problems. Constructing S-scheme heterojunction by reasonably matching the energy band structure to realize efficient photocatalytic hydrogen evolution is an attractive choice. In this work, the C3N5/TiO2 S-scheme photocatalysts was constructed by matching C3N5 with a more negative conduction band (CB) and TiO2 with a more positive valence band (VB). A series of characterization results confirmed that the S-scheme heterojunction achieves overall spatial separation of effective photogenerated carriers and accelerates the recombination of redundant electrons and holes. The photocatalytic hydrogen production performance of the TCN2 is 6.9 times and 30 times higher than that of C3N5 and TiO2, respectively, which is ascribed to the unique charge transfer mechanism of the S-scheme heterojunction and significantly enhanced photocatalytic activity. The simple construction of S-scheme heterojunctions in this work provides a new strategy for research in other fields.

High-efficiency Ni-Co alloy encapsulated in N-doped carbon layer (Ni1Co2@NC-APTES) catalysts were prepared via simple Ni-Co-MOF pyrolyzation and applied in the selective hydrogenation of nitrocyclohexane (NCH) to cyclohexanone oxime (CHO). The results show that the alloy effects between Ni and Co can highly promote catalytic activity. The appropriate Ni addition can facilitate the reduction of CoOx and increase zero-valent Co (Co0) amounts. Moreover, pyridinic-N doping increases the Lewis basicity, which favors the intermediate cyclohexylhydroxylamine (N-CHH) conversion to CHO. Additionally, the in-situ DRIFT and density functional theory (DFT) calculations propose the mechanism for NCH hydrogenation in ethylenediamine (EDA) and the results show that the EDA changes the reaction path of NCH hydrogenation to CHO, prefers to form N-CHH, and significantly reduces the whole reaction energy barrier of NCH to CHO. Moreover, the Ni1Co2 (111) crystal surface with the lowest d-band center and the strongest Ni-Co alloy effects presents the highest adsorption energies of H2 and NCH, the lowest adsorption energies of H* and CHO, and the lowest energy barrier of the alpha-H transfer which is conducive to form the N-CHH. Under the optimum conditions, the Ni1Co2@NC-APTES gives 93.6% selectivity to CHO at 94.5% NCH conversion in EDA.