Reaction Mechanism Research Articles

A Theoretical Study on the Mechanism of Bifunctional Brønsted Acid/Base-Catalyzed CO2-Fixation Reaction with Homoallylic Amine.

The reaction mechanism and the enantioselectivity of the Brønsted acid/base (trans-stilbene diamine, simplified by BAM)-catalyzed CO2 fixation with homoallylic amine have been investigated using density functional theory (DFT) calculations. The proposed mechanism involves the initial activation of the amine by the Brønsted acid, followed by the nucleophilic attack of the amine on CO2 to form a carbamate intermediate. The Brønsted base subsequently deprotonates the carbamate intermediate to form the cyclic carbamate product, regenerating the Brønsted acid catalyst. The C-O cyclization is the enantio-determining step. The hydrogen bond network formed by the catalyst and substrate, similar to an enzyme pocket, plays a key role in stereoselectivity. In addition, the energy decomposition analysis (EDA) confirms that hydrogen bonding is driven by orbital and electrostatic attractions. The more Brønsted basic BAM catalyst (OMe at the quinoline 7-position) exhibits enhanced enantioselectivity.

Computational Modeling of the Enzymatic Achmatowicz Rearrangement by Heme-Dependent Chloroperoxidase: Reaction Mechanism, Enantiopreference, Regioselectivity, and Substrate Specificity.

The chloroperoxidase from Caldariomyces fumago (CfCPO) catalyzes the oxidative ring expansion of α-heterofunctionalized furans via the Achmatowicz rearrangement, providing an elegant tool to convert furan rings into complex-prefunctionalized scaffolds. However, the mechanism of this transformation remains unclear. Herein, the CfCPO-catalyzed reaction of rac-1-(2-furyl)ethanol (1a) is studied by quantum chemical calculations and molecular dynamics simulations. The calculations reveal that the conversion follows the general mechanism of the Achmatowicz reaction. Notably, the binding of 1a to the enzyme's active site influences the Compound I (Cpd I) formation, and the (R)-1a enantiomer binding results in a lower barrier compared to (S)-1a, explaining the observed (R)-enantiopreference toward a racemic substrate. Additionally, due to the weaker steric hindrance between the porphyrin ring and substrate, the nucleophilic attack of Cpd I on the furan core of 1a is preferred at the less-substituted C4=C5 bond, providing a rationale for the experimentally observed regioselectivity. Finally, the bottleneck residues in the substrate delivery channel and also the active site surroundings are proposed to be responsible for the substrate specificity of CfCPO. This study lays a theoretical foundation for the rational design of new CPOs that catalyze the Achmatowicz rearrangement with a broader substrate spectrum or specific stereopreference.

Elucidating the Dynamic Changes in the Mechanism of the Potential-Dependent Alkaline Hydrogen Evolution Reaction on Platinum

Elucidating the Dynamic Changes in the Mechanism of the Potential-Dependent Alkaline Hydrogen Evolution Reaction on Platinum

Tailored topotactic chemistry unlocks heterostructures of magnetic intercalation compounds

The construction of thin film heterostructures has been a widely successful archetype for fabricating materials with emergent physical properties. This strategy is of particular importance for the design of multilayer magnetic architectures in which direct interfacial spin-spin interactions between magnetic phases in dissimilar layers lead to emergent and controllable magnetic behavior. However, crystallographic incommensurability and atomic-scale interfacial disorder can severely limit the types of materials amenable to this strategy, as well as the performance of these systems. Here, we demonstrate a method for synthesizing heterostructures comprising magnetic intercalation compounds of transition metal dichalcogenides (TMDs), through directed topotactic reaction of the TMD with a metal oxide. The mechanism of the intercalation reaction enables thermally initiated intercalation of the TMD from lithographically patterned oxide films, giving access to a family of multi-component magnetic architectures through the combination of deterministic van der Waals assembly and directed intercalation chemistry.

Transient pulsed discharge preparation of graphene aerogel supports asymmetric Cu cluster catalysts promote CO2 electroreduction

Designing asymmetrical structures is an effective strategy to optimize metallic catalysts for electrochemical carbon dioxide reduction reactions. Herein, we demonstrate a transient pulsed discharge method for instantaneously constructing graphene-aerogel supports asymmetric copper nanocluster catalysts. This process induces the convergence of copper atoms decomposed by copper chloride onto graphene originating from the intense current pulse and high temperature. The catalysts exhibit asymmetrical atomic and electronic structures due to lattice distortion and oxygen doping of copper clusters. In carbon dioxide reduction reaction, the selectivity and activity for ethanol production are enhanced by the asymmetric structure and abundance of active sites on catalysts, achieving a Faradaic efficiency of 75.3% for ethanol and 90.5% for multicarbon products at −1.1 V vs. reversible hydrogen electrode. Moreover, the strong interactions between copper nanoclusters and graphene-aerogel support confer notable long-term stability. We elucidate the key reaction intermediates and mechanisms on Cu4O-Cu/C2O1 moieties through in situ testing and density functional theory calculations. This study provides an innovative approach to balancing activity and stability in asymmetric-structure catalysts for energy conversion.

Progress in Experimental Methods Using Model Electrodes for the Development of Noble-Metal-Based Oxygen Electrocatalysts in Fuel Cells and Water Electrolyzers.

Hydrogen plays a key role in maximizing the benefits of renewable energy, and the widespread adoption of water electrolyzers and fuel cells, which convert the chemical energy of hydrogen and electrical energy into each other, is strongly desired. Electrocatalysts used in these devices, typically in the form of nanoparticles, are crucial components because they significantly affect cell performance, but their raw materials rely on limited resources. In catalyst research, electrochemical experimental studies using model catalysts, such as single-crystal electrodes, have provided valuable information on reaction and degradation mechanisms, as well as catalyst development strategies aimed at overcoming the trade-off between activity and durability, across spatial scales ranging from the atomic to the nanoscale. Traditionally, these experiments are conducted using well-defined, simple model surfaces like bare single-crystal electrodes in pure systems. However, in recent years, experimental methods using more complex interfaces-while still precisely controlling elemental distribution, microstructure, and modification patterns-have been established. This paper reviews the history of those studies focusing on noble-metal-based electrocatalysts for oxygen reduction reactions and oxygen evolution reactions, which account for the majority of efficiency losses in fuel cells and water electrolyzers, respectively. Furthermore, potential future research themes in experimental studies using model electrodes are identified.

Dirhodium-Catalyzed Asymmetric Transformations of Alkynes via Carbene Intermediates.

ConspectusFunctionalization of alkynes is an established cornerstone of organic synthesis. While numerous transition metals exhibit promising activities in the transformations of alkynes via π-insertion or oxidative cyclometalation, Lewis π-acids offer a different approach. By coordinating with alkynes through π-bonding, Lewis π-acids facilitate nucleophilic addition, leading to the formation of alkenyl metal species. These species can undergo electron rearrangement to generate metal carbenes, which are crucial intermediates for subsequent carbene transfer reactions. This reaction pathway provides a versatile route for alkyne functionalization, especially in an asymmetric manner. Although the Lewis π-acid, gold(I), pioneered this reaction mode, the development of asymmetric variants remains challenging due to the linear coordination of gold(I). Therefore, expanding the range of catalysts beyond gold(I) complexes to other metal catalysts would facilitate further advances in chiral molecule construction and the exploration of novel reaction modes.In this Account, we present a concise review of alkyne multifunctionalization via dirhodium-catalyzed asymmetric transformations, providing the development of the modulation strategies and substrates and plausible reaction mechanisms. In the aromatization-driven strategy, the furanyl dirhodium carbene is generated from an enynone, which is terminated by enantioselective intramolecular C-H insertion, cyclopropanation, aromatic substitution, or the Büchner reaction, giving chiral dihydroindoles, dihydrobenzofurans, cyclopropane-fused tetrahydroquinolines, fluorenes, or cyclohepta[b]benzofurans. The cap-tether modulation strategy was developed in a subsequent study to balance the reactivity and selectivity of an azo-enyne. This strategy gave the first catalytic asymmetric cycloisomerization of azo-enyne, affording centrally and axially chiral isoindazole derivatives. The synergistic activation strategy, i.e., EWG activation and C-H···O interaction, was introduced to achieve the first dirhodium-catalyzed asymmetric cycloisomerization of enynes, providing a range of chiral cyclopropane-annulated bicyclic systems from enynals. Benefiting from these successes, difluoromethyl-substituted enynes were designed and proven to be effective substrates. With the corresponding benzo-1,6-enynes as the substrates, the enantioselective biscyclopropanation and the cascaded cyclopropanation/cyclopropenation were achieved using alkynes as dicarbene equivalents. Additionally, benzo-1,5-enynal generated vinyl dirhodium carbene, which reacted with a variety of alkenes via [2 + 1] cycloaddition, [4 + 3] cycloaddition, or formal allylation, giving spiro and fused polycyclic heterocycles. Coupling the synergistic activation strategy with desymmetrization, we further successfully achieved the asymmetric cycloisomerization of diynals, constructing furan-fused dihydropiperidines with an alkyne-substituted aza-quaternary stereocenter. Notably, by analyzing X-ray structures of several dirhodium-alkyne π-complexes, together with the results of DFT calculations and control experiments, we obtained evidence supporting the synergistic activation mode, making the well-defined paddlewheel-like dirhodium(II) stand out among the other metal complexes. We anticipate that our research will significantly advance the fields of dirhodium, alkyne, and carbene chemistry.

Conformational dynamics of a multienzyme complex in anaerobic carbon fixation.

In the ancient microbial Wood-Ljungdahl pathway, carbon dioxide (CO2) is fixed in a multistep process that ends with acetyl-coenzyme A (acetyl-CoA) synthesis at the bifunctional carbon monoxide dehydrogenase/acetyl-CoA synthase complex (CODH/ACS). In this work, we present structural snapshots of the CODH/ACS from the gas-converting acetogen Clostridium autoethanogenum, characterizing the molecular choreography of the overall reaction, including electron transfer to the CODH for CO2 reduction, methyl transfer from the corrinoid iron-sulfur protein (CoFeSP) partner to the ACS active site, and acetyl-CoA production. Unlike CODH, the multidomain ACS undergoes large conformational changes to form an internal connection to the CODH active site, accommodate the CoFeSP for methyl transfer, and protect the reaction intermediates. Altogether, the structures allow us to draw a detailed reaction mechanism of this enzyme, which is crucial for CO2 fixation in anaerobic organisms.

Determining the Magnetic Status of Active Sites on Nanocatalysts.

Identifying the atomic structure and chemical composition of active sites on nanocatalysts has been a long pursuit in heterogeneous catalysis. Yet, determining the magnetic structure of a well-defined active site is even more challenging. However, explicit morphology and reaction temperature have not been considered in identifying the magnetic behaviors of the nanocatalysts, especially in theoretical studies. Herein, we determined the magnetic status of nanoscale catalysts at finite temperatures by using atomistic spin models. The size dependence of the Curie point and the magnetic premelting have been discussed, indicating that the magnetic properties over a localized active center can greatly differ from the bulk. Therefore, the magnetic phase transitions and its concomitant magneto-catalytic effect can be induced at a considerably low temperature. Our analysis demonstrated that an 8 nm cobalt-based core-shell nanoparticle can achieve the optimal magnetization with Sabatier optimal activity for ammonia synthesis at 523 K, which is in accord with the reaction condition of the Haber-Bosch process. We believe our findings elucidate the importance of determining the localized magnetic configuration for active sites. Furthermore, including this unexcavated dimension in the dynamical simulations of the catalytic process can provide us with a more complete and comprehensive understanding of the reaction mechanism under working conditions.

Regioselective [3 + 2] Annulation of β,γ-Alkynyl-α-ketimino Esters with 1,3-Dicarbonyls: The Synthesis of Highly Functionalized Dihydrofurans.

A regioselective [3 + 2] annulation of β,γ-alkynyl-α-ketimino esters with 1,3-dicarbonyls is disclosed. A series of Z-selective dihydrofurans bearing an exocyclic double bond and a quaternary carbon center are accessed without the usage of base. Control and deuterium-labeling experiments have been investigated to probe into the reaction mechanism. The catalyst and base-free nucleophilic addition highlights the transformation.

Preparation and Properties of Epoxy Modified Acrylic Polymer

This paper describes the synthesis of a viscosity-reducing agent using butyl acrylate (BA), ethyl methacrylate (EMA), acrylic acid (AA) and N-hydroxymethylacrylamide (N-MAM) monomers through emulsion polymerization. A series of viscosity-reducing agents were developed by incorporating varying amounts of glycidyl methacrylate (GMA) monomers. The reaction mechanism of epoxy acrylate viscosity reducer was analyzed by Fourier transform infrared spectroscopy (FTIR). Additionally, the particle size and Zeta potential were used to analyze the stability of the polymer and the difference in the polymer after adding GMA monomer. Thermogravimetric (TG) analysis indicated a significant improvement in the thermal stability of the resin due to GMA modification. The viscosity reduction test results demonstrated a substantial decrease in the viscosity of heavy oil, along with a notable increase in the viscosity reduction rate. The FTIR analysis results confirmed that GMA successfully introduced polyacrylate molecular chains. Furthermore, particle size and Zeta potential measurements showed that the average particle size of the emulsion increased from 132 nm to 187 nm, while the Zeta potential changed from −43 mV to −40 mV with the addition of 15% GMA. Compared with W0, the final thermal degradation temperature of W15 increased from 450 °C to 517 °C. When the GMA content reached 15 wt%, the maximum weight loss temperature increased by approximately 12 °C compared to the sample without GMA. Specifically, adding 8% W15 epoxy acrylate resulted in an 89% viscosity reduction rate for heavy oil, demonstrating an excellent viscosity reduction effect. This study successfully developed a novel epoxy acrylate viscosity reducer using a simple synthesis method, showcasing excellent stability, cost-effectiveness and remarkable viscosity reduction.

Evaluation of Semiempirical Quantum Mechanical Methods for Zr-Based Metal-Organic Framework Catalysts.

Zr-based metal-organic frameworks (MOFs) are typically employed in heterogeneous catalysis due to their porosity, chemical and thermal stability, and well-defined active sites. Density functional theory (DFT) is the workhorse to compute their electronic structure; however, it becomes very costly when dealing with reaction mechanisms involving large unit cells and vast configurational spaces. Semiempirical quantum mechanical (SQM) methods appear as an alternative approach to simulate such chemical systems at low computational cost, but their feasibility to model catalysis with MOFs is still unexplored. Thus, here we present a benchmark study on UiO-66 to evaluate the performance of SQM methods (PM6, PM7, GFN1-xTB, GFN2-xTB) against hybrid DFT (M06). We evaluate defective nodes, ligand exchange reactions, barrier heights, and host-guest interactions with metal nanoclusters. Despite some caveats, GFN1-xTB on properly constrained models is the best SQM method across all studied properties. Under proper supervision, this protocol holds promise for application in exploratory high-throughput screenings of Zr-based MOF catalysts, subject to further refinement with more accurate methods.

A theoretical study on the mechanism and rate constants of luteolin and selenium dioxide.

This study investigates the reaction mechanism of luteolin with selenium dioxide in ethanol. Through a detailed search for transition states and thermodynamic energy calculations, it was found that the reaction proceeds via two possible pathways, leading to the formation of products P1 and P2, respectively. A common feature of both pathways is that the first elementary step results in the formation of the intermediate INT1. Kinetic calculations indicate that, within the temperature range of 273 to 340K, the apparent rate constant (k2) for the formation of intermediate INT1 is significantly larger than those of k3 and k4, and all three rate constants increase substantially with temperature. Interestingly, the product P1 from the first pathway is thermodynamically and kinetically feasible, and is in complete agreement with experimental results. In contrast, the product P2 from the second pathway contains a Se-O-Se ether bond, which exhibits dynamic stability in its molecular structure. In conclusion, this study not only validates the experimental findings but also provides theoretical guidance for the synthesis of novel organoselenium compounds. All calculations were performed using the DFT/M06-2X/6-31G(d,p) method. The solvent effect was considered by applying the IEFPCM model in all calculations. The free energy (∆G) of each compound at 298.15K was obtained with a correction factor of 0.967. The apparent rate constants for each step were calculated over a temperature range from 273.15 to 373.15K using transition state theory.

Plasma-driven synthesis of nitrogen-doped graphene: unveiling the reaction mechanism and kinetic insights.

The rotating arc plasma technique for the synthesis of nitrogen-doped graphene capitalizes on the distinctive attributes of plasma, presenting a straightforward, efficient, and catalyst-free strategy for the production of nitrogen-doped graphene. However, experimental outcomes generally fail to elucidate the atomic-level mechanism behind this process. Our research utilizes molecular dynamics simulations to explore theoretically the formation of radicals during the plasma-driven reaction between methane (CH₄) and nitrogen (N₂). The simulations present a complex reaction system comprising nine principal species: CH₄, CH₃, CN, CH₂, HCN, CH, N₂, H₂ and H. Notably, HCN and CN emerge as pivotal precursors for nitrogen doping. Optimal nitrogen concentrations enhance the synthesis of these precursors, whereas excessive nitrogen suppresses the formation of C₂ species, impacting the yield of nitrogen-doped graphene. Conversely, higher methane concentrations stimulate the generation of carbon radicals, augmenting the production of HCN and CN and thus, influencing the properties of the synthesized material. This work is expected to lay a theoretical foundation for the refinement of nitrogen-doped graphene synthesis processes. In this investigation, we employed the LAMMPS software package to explore the formation of free radicals during the methane-nitrogen reaction via molecular dynamics (MD) simulations. These simulations were conducted under an NVT ensemble, maintaining a constant temperature of 3500K with a time step of 0.1fs over a duration of 1000ps. To reduce the variability and enhance the reliability of the simulation outcomes, each simulation was meticulously conducted three times under identical parameters for subsequent statistical analysis.

Site-Selective and High-Density Gold Nanoparticle Photodeposition on the Edges of ZnO Nanowires.

Selective modification of chemically active sites on supports, such as steps, edges, and corners, with metal nanoparticles (NPs) is a challenging topic in the fields of catalysis and photocatalysis. However, the formation of site-selective, high-density metal NPs on a support has not yet been achieved. Radial ZnO mesocrystals composed of hexagonal nanowires (NWs) with {101̅0} sidewalls were synthesized by a simple solution-phase method. Here, we show that Au NPs are densely aligned along the edges of ZnO NWs by photodeposition from an O2-free aqueous methanol solution of HAuCl4, even though the Au complexes are uniformly adsorbed across the entire surface of the ZnO NWs. On the basis of the results of experiments and density functional theory calculations, we proposed a reaction mechanism of site-selective photodeposition involving the reduction of the Au complex by the excited electrons instantly relaxed at the edge sites followed by crystal growth. This study encourages us to apply site-selective photodeposition to other faceted semiconductor nanocrystals and to contribute to the improvement in their catalytic and photocatalytic activities.

The Effect of Phosphoric Acid on the Flame Retardancy and Interfacial Adhesion of Carbon Fiber with Thermoplastic Resin PA6

This study investigated the effect of phosphoric acid treatment on carbon fibers to enhance their flame retardancy, the impact of carbon fiber surface treatment conditions on the interfacial adhesion between carbon fibers and PA6, and the chemical reaction mechanisms on the carbon fiber surface. Phosphoric acid treatment resulted in a flame-retardant effect, with a limited oxygen index of over 52.8%, and V0 level flame retardancy characteristics in the UL-94 test when the concentration exceeded 0.5 vol.%. When the treatment time was fixed at 30 min, the tensile strength increased by approximately 2%, and the interfacial shear strength (IFSS) increased by approximately 11% at 0.5 vol.% phosphoric acid, accompanied by an increase in hydroxyl (C–O), carbonyl (C=O), phosphate (P–O), and phosphoryl (P=O) groups. However, at concentrations higher than 0.5 vol.%, the tensile strength decreased by approximately 90%, and the IFSS decreased by approximately 12%, compared to the untreated nonwoven fabric. When the treatment time was varied at 0.5 vol.% phosphoric acid, both the tensile strength and IFSS increased continuously up to 10 min, with a 31% increase in tensile strength and a 17% increase in IFSS, along with an increase in O=C–O, P–O, and P=O groups, as well as surface energy. After 10 min, the tensile strength decreased by approximately 20%, while the IFSS and surface energy remained relatively unchanged.

Electrocatalytic Pathways and Efficiency of Cuprous Oxide (Cu2O) Surfaces in CO2 Electrochemical Reduction (CO2ER) to Methanol: A Computational Approach

Carbon dioxide (CO2) can be electrochemically, thermally, and photochemically reduced into valuable products such as carbon monoxide (CO), formic acid (HCOOH), methane (CH4), and methanol (CH3OH), contributing to carbon footprint mitigation. Extensive research has focused on catalysts, combining experimental approaches with computational quantum mechanics to elucidate reaction mechanisms. Although computational studies face challenges due to a lack of accurate approximations, they offer valuable insights and assist in selecting suitable catalysts for specific applications. This study investigates the electrocatalytic pathways of CO2 reduction on cuprous oxide (Cu2O) catalysts, utilizing the computational hydrogen electrode (CHE) model based on density functional theory (DFT). The electrocatalytic performance of flat Cu2O (100) and hexagonal Cu2O (111) surfaces was systematically analysed, using the standard hydrogen electrode (SHE) as a reference. Key parameters, including free energy changes (ΔG), adsorption energies (Eads), reaction mechanisms, and pathways for various intermediates were estimated. The results showed that CO2 was reduced to CO(g) on both Cu2O surfaces at low energies. However, methanol (CH3OH) production was observed preferentially on Cu2O (111) at ΔG = −1.61 eV, whereas formic acid (HCOOH) and formaldehyde (HCOH) formation were thermodynamically unfavourable at interfacial sites. The CO2-to-methanol conversion on Cu2O (100) exhibited a total ΔG of −3.38 eV, indicating lower feasibility compared to Cu2O (111) with ΔG = −5.51 eV. These findings, which are entirely based on a computational approach, highlight the superior catalytic efficiency of Cu2O (111) for methanol synthesis. This approach also holds the potential for assessing the catalytic performance of other transition metal oxides (e.g., nickel oxide, cobalt oxide, zinc oxide, and molybdenum oxide) and their modified forms through doping or alloying with various elements.

Dynamics studies of H atom collision with KH molecule

Using the non-adiabatic potential energy surfaces (PESs) reported by Li et al. (Phys. Chem. Chem. Phys. 22 (2020) 16203), an in-depth examination of the abstraction and exchange reaction processes involving H colliding with KH was performed via the time-dependent wave packet method. The dynamics information is reported at state-to-state level of theory. Our findings suggest that the K(4p2P) + H2 product channel emerges through a non-adiabatic transition process. Given its similarity to the K(4s2S) + H2 product channel, this channel cannot be disregarded, particularly when J values are minimal. Additionally, our analysis revealed that among the three product channels of the H + KH reaction, the K(4s2S) + H2 channel consistently holds a dominant position. Scattering information from differential cross sections indicate that the forward abstraction reaction mechanism is predominant for the abstraction reaction, while the insertion reaction mechanism prevails for the exchange reaction.

Biochar doping of synthesized mordenite improves adsorption and oxidation in As(III) removal: Experiments and DFT calculations.

In this study, a composite material was synthesized through the co-pyrolysis of biochar doped with synthetic mordenite. The adsorption experiments conducted with BC@ASM on As(III) facilitated the determination of the optimal mass ratio of 20:1 (ASM: Yak dung) and a pyrolysis temperature of 500 °C. The adsorption properties of ASM and BC@ASM were examined through batch adsorption experiments and a range of characterization techniques. And the reaction mechanism was further elucidated by DFT calculations, revealing the essential difference in the adsorption of As(III) by ASM and BC@ASM .The adsorption kinetics of As(III) were found to align with both the pseudo-second-order and Elovich kinetic models, while the isothermal adsorption was consistent with the Freundlich model. The maximum theoretical adsorption capacities were determined to be 371.9 mg/g and 449.6 mg/g, respectively. When the initial concentration of arsenite (As(III)) is 100 mg/L, the optimal dosage of synthetic mordenite is determined to be between 6 and 8 g/L, while the optimal dosage of the composite material ranges from 5 to 6 g/L. The composite material demonstrated significant resistance to fluctuations in pH. Within the pH range of 2 to 12, the removal efficiency is sustained between 78.3% and 88.7%. Furthermore, the adsorption capacity exhibited minimal sensitivity to the presence of anions such as chloride (Cl⁻), nitrate (NO₃⁻), bicarbonate (HCO₃⁻), and sulfate (SO₄2⁻) in the surrounding environment. In addition, BC@ASM facilitated the formation of arsenite-tannic acid complexes, which markedly improved its adsorption capacity for arsenite. In conclusion, the composite material presents a viable approach for addressing arsenic contamination in aquatic environments, while the foundational data offers a novel perspective for the remediation of metallic pollutants.

In Situ Generation of Anatase-Rutile TiO2/g-C3N4 Composite Catalyst in High-Temperature Molten Salt.

Hydrogen evolution from water, catalyzed by solar energy, is a promising yet challenging endeavor. Small-sized catalysts usually exhibit high utilization and high performance in the hydrogen evolution field. However, the high surface energy tends to make them aggregate. In this study, we introduce a novel molten salt synthesis technique to develop a composite catalyst featuring a TiO2/C3N4 heterojunction to stabilize the small-sized TiO2. High-temperature molten salts create a highly polarized environment that facilitates the formation of a smaller-sized Ti precursor, thereby enhancing the integration of the heterojunction with C3N4 structures and significantly improving the photocatalytic hydrogen evolution performance. Additionally, the oxidation of sacrificial reagents was examined using a quasi-in-situ NMR technique, with a comprehensive discussion of the reaction products and mechanisms. This research offers valuable insights for employing the molten salt approach in the development of photocatalysts and other functional materials.