Catalytic Mechanism Research Articles

Catalytic pyrolysis mechanism of tetrabromobisphenol A by calcium oxide: A density functional theory study

In this paper, the mechanisms of catalytic pyrolysis of tetrabromobisphenol A (TBBPA) by calcium oxide (CaO) were studied through density functional theory methods. The results indicate that the phenolic hydroxyl group of TBBPA is the preferred site for CaO to extract protons, and the generated anion further transforms into 2,6-dibromophenol via demethylation and hydrogen transfer reactions. The reaction activity of CaO with hydrogen bromide is relatively high, with an energy barrier of 133.2 kJ/mol. CaO produces calcium ions, which combine with bromine ions to form calcium bromide to achieve the purpose of fixing bromine. In addition, the participation of calcium ions results in the OH bond being easier to crack, which further lowers the reaction energy barrier of keto-enol tautomerism reactions H2O produced during catalytic pyrolysis also has an obvious catalytic effect, and the energy barrier of the keto-enol tautomerism reaction decreased from 309.1 kJ/mol to 150.6 kJ/mol with the participation of H2O.

3d-orbital overlap modulated d-band center of high-entropy oxyhydroxide for efficient oxygen evolution reaction

As an emerging high entropy material, recently, a few studies have shown that high-entropy oxyhydroxides possess higher catalytic performance due to their multiple active sites and more excellent stability for the oxygen evolution reaction (OER). Although the high-entropy effect, cocktail effects etc. have been proposed for the catalytic mechanism, the electronic interaction mechanisms among multiple metal elements still require further in-depth investigation. Herein, a high-entropy oxyhydroxide (FeCoNiZnOOH) was synthesized. Experimental results and density functional theory (DFT) calculation demonstrate that there are electronic interactions and strong 3d orbital overlap among the four metals. This overlapping effect of the Fe/Co/Ni/Zn 3d orbitals shifts the d-band center downward, thereby reducing the adsorption barrier for oxygen intermediates during the reaction and accelerating the reaction kinetics. The FeCoNiZnOOH shows excellent electrocatalytic performance with a low overpotential of 206 mV at a current density of 20 mA cm−2, and a Tafel slope of 54.3 mV dec–1, which is better than the synthesized monometallic oxyhydroxide, bimetallic oxyhydroxide, medium entropy oxyhydroxides and commercial Ir/C catalyst. This work offers new insight into designing efficient OER catalysts through regulate the electronic structure and optimize electrochemical performance for high-entropy electrocatalysts.

A systematic study on Au-PDA@Fe3O4 core-shell catalysts for enhanced catalytic reduction of 4-nitrophenol

The development of nanogold catalysts with high activity and high stability is of great significance for their industrial applications. In this paper, Au-PDA@Fe3O4 catalysts were prepared through the gold sol adsorption method. First, micron-sized magnetic Fe3O4 spheres were synthesized via a solvothermal method, serving as the core to endow the catalyst with excellent recyclability. Subsequently, a layer of polydopamine (PDA) shell was polymerized on the magnetic core surface. By controlling the timing of introducing the gold sol containing Au nanoparticles (NPs), the spatial position of Au NPs within the PDA layer was regulated, leading to a series of magnetic core-shell nano gold catalysts with varying spatial positions of Au. Using the 4-nitrophenol (4-NP) hydrogenation as the probe, the influence of Au spatial position, Au size, and other conditions on the catalytic performance was investigated. Results showed that, in the prepared Au-PDA@Fe3O4-16 catalyst, the Au NPs are encapsulated within the PDA shell and positioned close to the outer layer. This not only provides remarkable stability to the Au NPs but also maintains their proximity to the surface of the PDA shell, allowing easier access of the substrate 4-NP to the Au NPs and conferring good reactivity upon the catalyst. The strong electron metal-support interaction between PDA and Au enables PDA to effectively stabilize Au NPs. The prepared Au-PDA@Fe3O4-16 catalyst exhibits excellent stability, maintaining a high conversion rate of 91% even after 14 cycles of use. Our findings not only deepen the understanding of the catalytic mechanisms involved but also pave the path towards the creation of highly efficient and robust gold-based catalysts, facilitating their widespread utilization in industrial applications.

Exploring the mechanism of alkali metal K-catalyzed biomass char gasification using in-situ DRIFTS and molecular simulation

Although alkali metal potassium (K)-catalyzed char gasification has been widely studied, the detailed mechanism of this process is still not fully understood. To study this catalytic mechanism in more detail, high-temperature in-situ DRIFTS experiments were carried out for the gasification of cellulose char with K and cellulose char without K under H2O and O2 atmospheres, transient gasification experiment of char with K under H2O atmosphere, and char with K gasification under isotope water atmospheres. Peaks at 1945 cm−1 and 2020 cm−1 were observed. Combined with the theoretical spectra obtained by quantum chemical simulations and the prediction of catalytic gasification intermediates by molecular dynamics simulations, these two peaks were confirmed to represent char-polyynes species. Based on this result, a new mechanism is proposed: K interacts with carboxyl groups and aromatic ketones to promote desorption, thereby exposing active sites. Then, K reacts with the edge of the activated char to form numerous highly active char-polyynes species. The polyynes edge of this char-polyynes phase provides ideal adsorption–desorption sites, enabling further reaction with the gasifier. Thus, gas desorption is promoted. The adsorption and desorption peaks of catalytic gasification under the H2O atmosphere were located at 1400 cm−1 and 1300 cm−1, and these peaks represented stable adsorption states and unstable desorption precursors, respectively. Based on this, adsorption–desorption theory was analyzed more comprehensively, and the adsorption–desorption process was divided into three stages: initial adsorption, intermediate conversion, and desorption. The comprehensive new mechanism proposed in this paper provides a better understanding of the nature of char catalytic gasification at a deeper level.

Construction of piezoelectric fenton-like system over BaTiO3/α-FeOOH for highly efficient degradation of demethylchlortetracycline

Heterogeneous Fenton-like system is a promising technique for wastewater treatment, while Fe2+ regeneration limits its degradation efficiency. Piezoelectric materials can produce free electrons under mechanical stress. Based on this, a piezoelectric Fenton-like system coupling piezoelectric effect and Fenton-like reaction was proposed. Composite material BaTiO3/α-FeOOH was synthesized by sol–gel and hydrothermal method. Under ultrasonic vibration BaTiO3 continuously generated free electrons, which reduced Fe3+ to Fe2+ and realized Fe3+/Fe2+ cycle. The piezoelectric Fenton-like system based on BaTiO3/α-FeOOH was used to remove demethylchlortetracycline (DMCT) from water. The degradation ratio of DMCT can reach 100 % within 5 min, and the coupled system exhibited excellent adaptability and stability. Free radical capture and quantitative detection determined that •OH and •O2− were the main active oxygen species. A comprehensive catalytic mechanism was proposed and supported by energy band structure analysis, finite element method simulation, and Density Functional Theory (DFT) simulation calculations. The piezoelectric electrons generated by BaTiO3 were transfered to α-FeOOH to improve the Fe3+/Fe2+ cycle. In addition, the possible degradation mechanism of DMCT was proposed through Ultra Pressure Liquid Chromatography-Mass Spectrometry (UPLC-MS) measurement and DFT calculation, and the overall pollution toxicity of DMCT was assessed according to toxicity prediction. Overall, this work provided a new insight on coupling effect between piezoelectric effect and Fenton-like reaction.

Effects of strain, pH and oxygen-deficient on catalytic performance of Ruddlesden-Popper oxide Srn+1RunO3n+1 (n=1, 2) for hydrogen evolution reaction

Due to low content of precious metals and good stability, Ruddlesden-Popper (R–P) structure oxides are considered as promising hydrogen evolution reaction (HER) catalysts. However, related research is scarce, hindering its further improvement. In this paper, effects of strain, pH, oxygen-deficient and layer numbers on HER catalytic performance of R–P structure oxides Sr2RuO4, Sr3Ru2O7 and Sr3Ru2O6 were comprehensively calculated for the first time. Our results confirm that oxygen-deficient R–P Sr3Ru2O6 is beneficial for its catalytic performance in alkaline environments. Ranking of catalytic performance in acidic environments: Sr2RuO4>Sr3Ru2O6>Sr3Ru2O7, relatively in alkaline environments: Sr3Ru2O6>Sr3Ru2O7>Sr2RuO4, which means pH actually affects the performance of R–P structure catalysts. In other words, acidic environments are conducive to the catalytic activity of Sr2RuO4, while alkaline environments are beneficial for Sr3Ru2O6 and Sr3Ru2O7. We also calculated the effects of tensile and compressive strains and found that 1% and 3% tensile strain can further enhance the HER catalytic performance of Sr3Ru2O6. Taking into account various practical factors, our work investigated the HER catalytic mechanism of R–P oxides, providing theoretical guidance for the development of R–P structure catalysts.

Purification and catalysis of choline dehydrogenase from Escherichia coli

Choline dehydrogenase (CHDH) is a membrane-bound enzyme belonging to the glucose-methanol-choline (GMC) oxidoreductase superfamily, which is characterized by a crucial FAD-binding domain essential for catalytic function. CHDH catalyzes the oxidation of choline to betaine aldehyde, which is further oxidized to betaine, a vital osmoprotectant and methyl donor for cellular physiology and metabolism. However, the detailed catalytic mechanism of CHDH still remains poorly understood. In our investigation, we gained purity E. coli CHDH samples in DDM (n-dodecyl-β-D-maltoside) and SMA (styrene maleic acid) copolymer respectively and examined their structural composition and catalytic activity separately. Our findings demonstrated the effectiveness of SMA, commonly employed for extracting transmembrane proteins and can preserve the natural bio-membrane environment surrounding the enzyme, in extracting peripheral membrane proteins like CHDH here, which lacks transmembrane helices. CHDH exhibited a trimeric conformation in SMA, whereas it existed as monomers in DDM, as determined by our negative staining analysis. Our experiments also revealed that highly pure E. coli CHDH could only oxidize choline to betaine aldehyde but failed to further oxidize betaine aldehyde to betaine as determined by the biochemical and enzymatic reaction kinetic assays. In addition, the enzyme in SMA displayed greater catalytic activity compared to that in DDM. Furthermore, we confirmed the crucial role of His473, which is hypothesized to be a critical site for substrate binding from our structural comparative analysis between CHDH and its highly homologous choline oxidase, in the catalytic activity of the enzyme through gene mutation. Our work also sheds light on CHDH’s contribution to cellular osmotic tolerance through gene knockout. This research enhances our better understanding of CHDH within cellular biochemistry and metabolic pathways.

Efficient catalytic oxidation of xylose to formic acid with the oxygen vacancies of CeO2 promoted the vanadium catalysts anchored on biochar

The catalytic oxidation of carbohydrates for the preparation of formic acid (FA) is an prominent route for high-value utilisation of biomass. Reforming xylose, a biomass derivative, into FA with high efficiency is essential for the advancement of non-homogeneous V-type catalysts. Here, we present the self-assembly of V and Ce onto a cellulose pulp for the synthesis of oxygen vacancy (Ov)-rich non-homogeneous-bimetallic catalysts (5Ce-VOx/BC-600). Under the optimised conditions, 71.46 % FA was obtained, which far exceeded the catalytic performance of the single-metal catalyst. Furthermore, the 5Ce-VOx/BC-600 catalyst showed excellent stability and reusability. Kinetic studies revealed that glyceric and glycolic acids served as the pivotal intermediates, undergoing subsequent deacidification and oxidation processes to yield FA and CO2. The analysis of the catalytic mechanism indicated that the incorporation of Ce enhanced the quantity of acidic sites and the concentration of Ov in the 5Ce-VOx/BC-600 catalyst, which promoted substrate adsorption and O2 activation. Meanwhile, the catalyst showed high lattice oxygen (OL) mobility and assisted the redox cycle of V5+/V4+ to oxidise xylose to FA. Significantly, the synergistic effect of Ce, V species and Ov enhances the OL mobility of the catalysts, thus promoting the efficient oxidation of xylose. The catalytic system was further extended to the oxidation of other biomass derivatives to FA, demonstrating excellent catalytic performance.

Precise synthesis of cyclopropyl methyl ketone via proton transfer of 5-chloro-2-pentanone driven by hydrogen bonds

The traditional synthesis methods of cyclopropyl methyl ketone (CPMK) have some disadvantages such as low yield, slow reaction rate and unclear catalytic mechanism. To solve these problems, a new strategy is developed to synthesize CPMK from 5-chloro-2-pentanone (CPE) using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). Experiment results show that the yield of CPMK reached a maximum of 96.5% in DBU at 40°C for 30min. The mechanism study shows that the hydrogen bond between DBU and CPE is the key to drive the deprotonation and cyclization of CPE. The hydrogen bond is formed between the N atom on C=N of DBU and the α-H on the methylene group associated with the carbonyl group on CPE. The catalyst DBU is converted into [DBUH]+Cl−, which can be reclaimed and recycled completely. The density functional theory (DFT) calculation confirmed the existence of molecular hydrogen bonds and proved that the hydrogen bond driving force is the key to the reaction. The hydrogen bond driven mechanism provides a new idea for the basic research of cyclization reaction.

Structure–function analysis of tRNA t6A-catalysis, assembly and thermostability of Aquifex aeolicus TsaD2B2 tetramer in complex with TsaE

The universal N6-threonylcarbamoyladenosine (t6A) at position 37 of tRNAs is one of core post-transcriptional modifications that are needed for promoting translational fidelity. In bacteria, TsaC utilizes L-threonine, bicarbonate and ATP to generate an intermediate threonylcarbamoyladenylate (TC-AMP), of which the TC-moiety is transferred to N6 atom of tRNA A37 to generate t6A by TsaD with support of TsaB and TsaE. TsaD and TsaB form a TsaDB dimer to which tRNA and TsaE are competitively bound. The catalytic mechanism of TsaD and auxiliary roles of TsaB and TsaE remain to be fully elucidated. In this study, we reconstituted tRNA t6A biosynthesis using recombinant TsaC, TsaD–TsaB and TsaE from thermophilic Aquifex aeolicus and determined crystal structures of apo-form and ADP-bound form of TsaD2B2 tetramer. Our TsaD2B2–TsaE–tRNA model coupled functional validations reveal that the binding of tRNA or TsaE to TsaDB is regulated by C-terminal tail of TsaB and a helical hairpin α1–α2 of TsaD. A. aeolicus TsaD2B2 or TsaDB possesses a basal divalent ion-dependent t6A-catalytic activity that is stimulated by TsaE at the cost of ATP consumption. Our data suggest that binding of TsaE to TsaDB induces conformational changes of α1, α2, α6, α7 and α8 of TsaD and C-terminal tail of TsaB, leading to release of tRNA t6A and AMP. ATP hydrolysis-driven dissociation of TsaE from TsaDB resets an active conformation of TsaDB. Dimerization of thermophilic TsaDB enhances thermostability and promotes t6A-catalytic activity of TsaD2B2–tRNA, of which GC base pairs in anticodon stem are needed for correct folding of thermophilic tRNA at higher temperatures.

MoS2 Stabilize Ti3C2 MXene for Excellent Catalytic Effect of Thermal Decomposition of Ammonium Perchlorate

Ammonium perchlorate (AP), the most widely used oxidizer in energetic materials, is crucial for studying catalytic thermal decomposition. Newly discovered Ti3C2 MXene and MoS2 demonstrating promising prospects in the field of the pyrolysis catalyst in AP. In this study, we employed a hydrothermal method to anchor nano-sized MoS2 in situ on the surface of Ti3C2 MXene, leading to the fabrication of MoS2-Ti3C2 nanocomposites. Various characterizations indicated that MoS2 was attached to the surface and edges of Ti3C2, thereby enhancing the stability and conductivity. Results revealed that upon the addition of 4 wt% MoS2-Ti3C2, the low-temperature decomposition peak of AP reduced from 331.2 °C to 296.6 °C, while the high-temperature decomposition peak advanced from 427.5 °C to 387.1 °C, showing a superior catalytic effect compared to the individual MoS2 or Ti3C2. Additionally, the catalytic mechanism of MoS2-Ti3C2 on the thermal decomposition of AP may involve enhanced electrical conductivity, facilitating rapid proton transfer (H+), accelerated redox reactions, prompt release of gas products, and thereby expediting the progression of the decomposition reaction. Consequently, it can be anticipated that anchoring MoS2 on the surface of Ti3C2 represents an effective strategy for enhancing the catalytic activity of Ti3C2 MXene towards the thermal decomposition of AP.

Recent achievements in nickel based electrochemical biorefinery of 5-hydroxymethylfurfural

The electrochemical conversion of biomass offers a sustainable approach for energy recycling and environmental protection. Specifically, the electro-oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid is notable for its potential to produce value-added products, including biodegradable plastics and other environmentally friendly materials. A critical factor in this process is the performance of the catalysts. Nickel-based catalysts have shown high efficiency and durability, primarily due to the formation of Ni-OOH active sites. This paper reviews recent advancements in the nickel-based electrocatalytic oxidation of HMF, including the use of Ni, Ni alloys, Ni oxides, Ni hydroxides, and other Ni complex, and discusses the underlying catalytic mechanisms. Additionally, it introduces the coupling reactions, various reactor designs and outlines future research directions, focusing on exploring reaction mechanisms, developing electrocatalysts, and practical applications of this technology.

Multisite Pt/H2Ti2O5-TiO2 catalyst for formaldehyde oxidation

The development of multisite catalysts that simultaneously satisfy compositional, spatial arrangement and functional requirements remains a significant challenge. Herein, we report a supported Pt catalyst on surface hydroxyl- and oxygen-vacancy-rich H2Ti2O5/TiO2 composite nanotubes for formaldehyde (HCHO) oxidation. Our study demonstrates that H2Ti2O5/TiO2 nanotubes can be prepared by a hydrothermal method and in particular, using Na2[Pt(OH)6] as a metal precursor yields ultrasmall and uniformly distributed Pt nanoparticles on the nanotube surface. In situ diffuse reflectance infrared Fourier transform spectroscopy analyses reveal that HCHO oxidation over the Pt/H2Ti2O5-TiO2 catalyst occurs via a cooperative catalysis mechanism: Pt facilitates the splitting of O2, surface hydroxyl group on H2Ti2O5 serves as HCHO adsorption site and oxygen vacancy on the TiO2 surface promotes the dissociation of H2O to generate active OH species. Consequently, the Pt/H2Ti2O5-TiO2 catalyst exhibits an impressively high mass-specific reaction rate of 118.0 μmol gPt−1 s−1 and excellent stability, outperforming previously reported HCHO oxidation catalysts.

Fabrication of MOF-carbonized materials as ozone catalysts for water purification: Exploration of catalytic mechanisms

Due to their stability, the advent of MOF-derived catalysts ensures the applications of MOF-based materials, and they have been used in many catalytic systems. However, their application in ozone catalysis is limited, and the relevant mechanisms remain unclear. In this study, three MOF-carbonized materials (Me-MOF-C, Me: Fe, Cu, and Zn) were synthesized as ozone catalysts for water purification. When combined with ozone, all the Me-MOF-C promoted target removal compared to the Me-MOF/O3 systems, and Fe-MOF-C was optimal due to its superior ozone utilization efficiency. ROS quantification indicated that the •OH in the Fe-MOF-C/O3 system was approximately 48.0 times that of the single ozone system. Kinetic analysis demonstrated that over 90 % of the target was removed by •OH in the Fe-MOF-C/O3 system. Then, the catalytic mechanism of Fe-MOF-C was investigated. The surface hydroxyl and protonation effect of Fe-MOF-C presented limited activity. In comparison, H2O2 in the solution and Fe2+ on the Fe-MOF-C surface were more crucial. AcOH control experiments revealed a positive correlation between •OH and H2O2. H2O2 decomposition experiments further indicated that although the Fe-MOF-C/O3 system utilized H2O2 faster, only the coexistence of ozone and Fe-MOF-C could facilitate it more. Results of Fe2+ regulation suggested that it was related to the way of surface Fe2+ acted. The main contribution of Fe2+ to producing •OH was not through Fe2+ ozonation or reaction with H2O2, but it likely involved the efficient conversion of H2O2 into HO2ˉ, which subsequently decomposed ozone to produce •OH more efficiently. Finally, a possible catalytic pathway was proposed.

Understanding and Tuning the Effects of H2O on Catalytic CO and CO2 Hydrogenation.

Catalytic COx (CO and CO2) hydrogenation to valued chemicals is one of the promising approaches to address challenges in energy, environment, and climate change. H2O is an inevitable side product in these reactions, where its existence and effect are often ignored. In fact, H2O significantly influences the catalytic active centers, reaction mechanism, and catalytic performance, preventing us from a definitive and deep understanding on the structure-performance relationship of the authentic catalysts. It is necessary, although challenging, to clarify its effect and provide practical strategies to tune the concentration and distribution of H2O to optimize its influence. In this review, we focus on how H2O in COx hydrogenation induces the structural evolution of catalysts and assists in the catalytic processes, as well as efforts to understand the underlying mechanism. We summarize and discuss some representative tuning strategies for realizing the rapid removal or local enrichment of H2O around the catalysts, along with brief techno-economic analysis and life cycle assessment. These fundamental understandings and strategies are further extended to the reactions of CO and CO2 reduction under an external field (light, electricity, and plasma). We also present suggestions and prospects for deciphering and controlling the effect of H2O in practical applications.

Enhanced removal of phenolic pollutants over MnO2 initiated by peracetic acid: In situ generation of a heterogeneous Mn(III)-hydroperoxo complex

Widely distributed manganese oxides are among the strongest oxidants in nature and effectively enhance the water decontamination by peracetic acid (PAA) activation. However, the precise mechanism requires further investigation. In this work, the intrinsic mechanism of PAA activation by MnO2 was systematically studied. Through in situ diffuse-reflectance UV–vis spectra and resonance Raman spectra, the active species was identified as a non-radical heterogenous Mn(III)-hydroperoxo complex. During the process, PAA drastically converted Mn(IV) in MnO2 into homogeneous Mn(II), which subsequently generated the active Mn(III) species in the aid of PAA on the surface of MnO2. By interacting with pollutants, the peroxide bond in Mn(III)-hydroperoxo broke, accompanied by the regeneration of Mn(IV). Eight phenolic compounds having para-substituent of –CH3, −H, −Cl, –COCH3, –CHO, –COOH, –COOCH3, and –NO2 were selected for degradation. Due to the electrophilic character of Mn(III)-hydroperoxo, the removal rates were 100 %, 100 %, 98.8 %, 69.8 %, 49.6 %, 30.2 %, 28.1 %, and 3.0 % respectively at the 45 min of experiment. The MnO2/PAA system was also readily coupled with a filtration membrane for continuous treatment of phenol in nearly 100 % removal efficiency. This study not only offered an efficient non-radical PAA activation protocol for water decontamination, but also elucidated the catalytic mechanism and redox cycle of MnO2 in PAA solution in the selective oxidation process.

Preparation of NiCo hydroxide by chloride corrosion for electrocatalytic upcycling of polyethylene terephthalate plastic waste

Upcycling plastic waste into value-added chemicals is an innovative strategy that addresses environmental concerns and creates economic value. As one of the polyesters that is widely used, polyethylene terephthalate (PET) plastic waste is employed as the model substrate. Here we report a chloride corrosion method to synthesize bimetallic hydroxide catalysts on nickel foam. By using a nickel–cobalt hydroxide catalyst (NiCo-OH/NF), we demonstrate an electrocatalytic oxidation strategy to transform real-world polyethylene terephthalate (PET) water bottle into potassium formate and terephthalic acid (TPA) with high Faraday efficiency of 92.1 % at 1.40 V vs. RHE. The in situ spectroscopy and theoretical calculations provide insights into the catalytic mechanism especially active sites, pivotal intermediates, and favorable pathways. This work highlights the significant potential of electrochemical conversion as a means of achieving PET upcycling.

Cobalt/iron bimetallic oxide coated with graphitized nitrogen-doped carbon (Fe2O3-CoO@NC) derived from cobalt/iron solid complex as peroxymonosulfate (PMS) activator for efficient bensulfuron-methyl degradation

Cobalt/iron bimetallic oxide coated with graphitized nitrogen-doped carbon (Fe2O3-CoO@NC) was synthesized by convenient solid phase coordination combined with calcination method to activate PMS for the degradation of BSM. A series of Co/Fe bimetallic oxides with different metal ratios were designed and prepared to select the most efficient catalyst and Fe2O3-CoO@NC(Co:Fe = 1:1) demonstrated the highest catalytic activity and the lowest ions leaching. The reasons for high catalytic activity of Fe2O3-CoO@NC(Co:Fe = 1:1) were evaluated by a range of characterization techniques and the results showed it stemmed from higher mental content and larger current density. Complete (100%) degradation of 10 g L−1 BSM was achieved within 10 min under the conditions of 0.05 g L−1 catalyst and 0.3 mmol/L PMS dosage at 25 °C. Moreover, Fe2O3-CoO@NC(Co:Fe = 1:1) showed more excellent catalytic activity and lower ions leaching than Fe2O3, CoO and Fe2O3-CoO, indicating superior bimetallic synergy and carbon encapsulation effect. Furtherly, radical experiments and XPS analysis revealed the main active species and catalytic mechanism of the Fe2O3-CoO@NC/PMS system, respectively. Finally, the degradation pathway of BSM by Fe2O3-CoO@NC/PMS system was deduced by LC-TOF-MS. This paper is aimed to provide a new insight into the convenient preparation method for the construction of catalysts which could reach efficient removal of complex organic pollutants.

Preventing Nitrite Desorption via Switching Hydrogenation Position: A Dual-Site Approach for Selective Nitrate Reduction to Ammonia.

The electrochemical nitrate reduction reaction (NO3RR), which converts harmful nitrates into valuable ammonia (NH3) with zero carbon emission, is one of the most promising alternatives to the Haber-Bosch process. However, the NO3RR process is complex and involves multiple proton-coupled electron transfers that generate intermediates or byproducts, such as NO2 -, resulting in low ammonia yields and faradaic efficiency (FE). Herein, by constructing a FeCu bimetallic catalyst (FeCu-NC), the hydrogenation position of *NO3 is switched at the FeCu dual-atom site, preventing the desorption of *NO2 intermediate. Furthermore, electron transfer from Cu to Fe sites mimics the electron flow direction in natural nitrite reductase enzymes and accelerates the reduction of *NO2 to NH3, achieving efficient conversion of NO3 - to NH3. A 24-hour electrocatalytic experiment with FeCu-NC demonstrates negligible NO2 - formation throughout the NO3RR process, with an ammonia production rate of 6.13mgh-1mgcat -1 and an impressive FE of 95%, which are remarkably superior in comparison to most of the NO3RR electrocatalysts. This work opens new avenues for the fundamental understanding of catalytic mechanisms and the development of next-generation catalysts for sustainable ammonia production.

Electrochemiluminescence Reveals the Structure-Catalytic Activity Relationship of Heteroatom-Doped Carbon-Based Materials.

Heteroatom doping can change the chemical environment of carbon-based nanomaterials and improve their catalytic performance. Exploring the structure-catalytic activity relationship of heteroatom-doped carbon-based materials is of great significance for studying catalytic mechanisms and designing highly efficient catalysts, but remains a significant challenge. Recently, reactive oxygen species (ROS)-triggered electrochemiluminescence (ECL) has shown great potential for unveiling the mechanism by which heteroatom-doped carbon-based materials catalyze the oxygen reduction reaction (ORR), owing to the high sensitivity of these materials to the properties of the electrode surface. Herein, two kinds of heteroatom-doped porous carbon (denoted as NP-C and N-C) are synthesized and analyzed by monitoring the cathodic ECL of luminol-H2O2 in the low negative-potential region. P, N-doped NP-C exhibitsbetter catalytic ability for activating H2O2 to generate large amounts of •OH and O2 •-, compared with N-C. A sensitive antioxidant-mediated ECL platform is successfully developed for detecting the antioxidant levels in cells, exhibiting considerable potential for evaluating the antioxidant capacity. The relationship between the structure and catalytic mechanism of heteroatom-doped carbon-based materials is successfully explored using ECL, where this method can be universally applied to carbon-based materials.