Research progress on catalytic applications of novel two-dimensional layered material MXene

In recent years, MXene materials as emerging two-dimensional transition metal carbides or nitrides, have shown a significant potential as novel catalytic materials due to their high conductivity, rich surface functional groups, and two-dimensional layered structure. In catalytic reactions, MXene materials not only provide more active sites but also enhance catalytic performance by modulating their structure and surface chemistry, thus overcoming the limitations of current catalytic technologies. This article summarizes the preparation methods of MXene materials and systematically reviews their application progress and research status in photocatalysis, thermocatalysis, and electrocatalysis. It also discusses the mechanisms and performance optimization strategies of MXene in different catalytic reactions, as well as the issues related to the stability and recyclability of MXene materials. Finally, the article concludes by outlining the future research priorities of MXene materials and their application prospects in energy conversion and environmental remediation.

Flow pattern evolution and three-dimensional liquid film distribution characteristics in falling film over elliptical horizontal tubes

To address the unclear regulation mechanisms of liquid film distribution in industrial falling film heat exchangers,this paper proposes a novel method that synergistically regulates the three-dimensional hydrodynamics of liquid films through superhydrophilic surface and elliptical tube installment.A combined visualization-spectroscopy experimental platform was constructed,integrating a confocal displacement spectrometer(1 000 Hz/1 μm precision) and high-speed imaging for coordinated observation.The temporal and spatial evolution of liquid films during the transition from droplet flow to columnar flow was quantitatively analyzed with Re=59-220.The study reveals that a superhydrophilic surface fabricated via boehmite nanostructure modification(contact angle <5°) results in an11% reduction with liquid film thickness compared to hydrophilic tubes.When the major axis of the elliptical tube is oriented vertically,the circumferential uniformity of the liquid film improves,and axial central effect is enhanced,such as that the liquid film thickness at l*=0.5 increases by 35%-41% compared to l*=0.A predictive formula relating film thickness to Reynolds number was established,and the pattern of deviation from the classical Nusselt theory at Re(Re=88-118) was revealed.These findings provide theoretical support for the optimized design of industrial falling film heat exchangers.

Research on the influence of Tesla valve structural parameters on one-direction flow characteristic and modification

The Tesla valve is a type of passive one-way valve. The enhancement of its one-direction flow characteristic can optimize the fluid control efficiency and improve the compactness of the valve structure. To address this,an innovative structural modification was proposed based on the existing Tesla valve. Valve components were fabricated by Three-Dimensional(3D) printing, and a platform was established to verify the accuracy of numerical simulations. The impacts of baffle height, valve spacing, and the number of stages on its one-direction flow characteristic were analyzed via simulations. The results demonstrated that the one-direction flow characteristic of the modified single-stage Tesla valve was elevated by 20.82%. In comparison with the original eight-stage structure, while reducing two stages, the forward pressure drop was decreased and the reverse pressure drop was remarkably increased, enabling over 24.52%space savings.

Study on esterification kinetics of glycerol monobutyrate

In a stirred tank reactor, solid acid catalyst was used to catalyze the esterification of glycerol and butyric acid to prepare monoglyceride. The effects of reaction temperature, reaction time, and catalyst dosage on the reaction process were investigated. We studied the chemical equilibrium and reaction rate of glycerol and butyric acid esterification to produce monoglyceride butyrate. A kinetic model for second-order reversible reactions was established based on experimental results. The results showed that the chemical equilibrium constant for synthesizing monoglycerides increased with temperature, and the variation followed the Van't Hoff equation. The reaction was endothermic. The reaction rate constants for esterification, hydrolysis, and esterification of butyric acid glycerides with 2%catalyst by mass of butyric acid satisfied the Arrhenius equation, and the corresponding activation energies were 60.1, 51.2, and 63.3 kJ·mol~(-1), respectively.

Highly efficient green synthesis of Heterophyllin B assisted by a soluble tag under continuous flow

In response to the problems existing in the traditional synthesis of cyclic peptides, such as the use of toxic solvents(e. g., DMF, DCM), controlled use of deprotection reagents(e. g., piperidine), low cyclization efficiency, and the dependence on specific amino acids(e. g., Cys, Lys), this work proposed a green and efficient strategy for cyclic peptide synthesis. This strategy is based on a novel soluble silicon-based hydrophobic tag,(bis(4-（（triisopropylsilyl）oxy）phenyl)methyl)hydrazine(BTPH), combined with continuous flow microreactor technology, to construct an integrated system consisting of three modules: coupling, deprotection(using tetrahydropyrole instead of piperidine), and washing and extraction. Moreover, low-toxicity ethyl acetate is used to replace traditional harmful solvents like DMF. The results show that this strategy can efficiently synthesize the linear Heterophyllin B peptide hydrazine, with a crude product purity of over 90%. The cyclization is completed through anin-situgenerated acyl azide intermediate under mild conditions, with a cyclization conversion rate over 30%higher than traditional methods, improved atom economy, and a reduction in overall synthesis cost by approximately60%. This study provides a feasible path for the green continuous flow synthesis of natural cyclic peptides and has significant reference value for the modular preparation of complex peptides.

Phosphorus doping and oxygen vacancies synergistically enhanced In₂O₃ photocatalytic CO₂ reduction

Due to the inherent defects(such as high photogenerated carrier recombination rate and insufficient CO_2adsorption/activation capacity),In_2O_3 has low photocatalytic CO_2 reduction activity and product selectivity,so it is necessary to improve its photocatalytic CO_2 reduction performance through structure/component regulation.In this study,the phosphorus(P)-doped and oxygen-vacancies co-modified nano-flower In_2O_3 catalyst(xP-In_2O_3) was successfully prepared by a hydrothermal-roasting method coupled with the gas phase phosphating.By controlling the phosphating reaction time(x h),the P-doping amount and oxygen-vacancies concentration were optimized,thereby improving the photocatalytic CO_2 reduction activity and product selectivity.Under the gas-solid photocatalytic reaction system,the results show that the CO and CH_4 yields of 1.0P-In_2O_3 are 4.13 μmol·g~(-1)·h~(-1) and 2.54 μmol·g~(-1)·h~(-1),which are 2.6 times and 12.5 times of that of unmodified In_2O_3 respectively.These values represent that P-doping and oxygen-vacancies synergistically enhance the CO_2 reduction activity of In_2O_3 and significantly improve the selectivity of CH_4.The photoelectrical properties and CO_2 adsorption performance tests reveal that the synergistic construction of P doping and oxygen-vacancies in In_2O_3 significantly promote the separation and migration of photoinduced electron-hole pairs.This enhancement in charge separation,coupled with improved CO_2 adsorption and activation capacities,directly leads to heightened photocatalytic CO_2 reduction activity and enhanced selectivity toward CH_4 formation.Further in-situ infrared spectroscopic studies on the reaction mechanism demonstrate that the sequential reaction pathway for CO_2 conversion to CH_4 on the surface of 1.0P-In_2O_3 follows:*CO_2→*CO→*CHO→*CH_3O→CH_4.This work provides an effective strategy for constructing In_2O_3-based catalysts with high activity and high CH_4 selectivity.

Ni²⁺surface-doped CdS nanocrystals prepared in nanoreactors and their properties

Nickel ion(Ni~(2+)) surface-doped cadmium sulfide(CdS) nanocrystals were synthesized by inverse miniemulsion method combined with solvothermal treatment.The influence of the nanocrystal precursor synthesized in nanoreactors on miniemulsion stability was investigated.The grain sizes,morphological features,element content and chemical valence states of the surface-doped or bulk-doped nanocrystals with the different Ni~(2+) doping amounts were characterized,which were solvothermally obtained.The results showed that the stable nanoreactors were approximately 330 nm in sizes when the Cd~(2+) salt/H_2O mass ratio was 75 mg/1.5 g.With the Ni~(2+) doping amount increase after precursors ripening,the solvothermal-treated Ni~(2+) surface-doped CdS nanocrystals of 1.17 mg Ni~(2+) salt/75 mg Cd~(2+) salt had a grain size of about 11 nm and a bandgap of 2.05 eV,exhibiting the good conductivity and the high light absorption.Using the regulation strategy in nanoreactors,it achieves the targeted surface modification of the Ni~(2+)surface-doped CdS.The research contributes a novel strategy to the development of advanced semiconductors.

Preparation and properties of ion imprinted modified lignin/graphene composite quantum dots

As a biomass resource with great application prospects,lignin has continuously attracted the attention and exploration of the industry in terms of improving its utilization rate and exploring its potential value.In the traditional fluorescence carbon dots modified by lignin for detecting metal ions,the detection results are "unpredictable",which restricts the development and application of such carbon dots to a certain extent.Ion-imprinted technology,by virtue of its specific ion-recognition mechanism,can strengthen the "specificity" and "selectivity" of carbon dots in recognizing metal ions,providing new research ideas for the field of carbon dots detecting metal ions.In this study,the amination modification of lignin was carried out first,and then the ion-imprinted modified lignin/graphene composite quantum dots(IIT/GQDs) with Co~(2+) s the template ion were prepared by citric acid pyrolysis method.The maximum excitation wavelength and emission wavelength of IIT/GQDs were measured as 318nm and 425 nm respectively by a fluorescence spectrometer.The average particle size of the composite quantum dots,which was measured by a transmission electron microscope,was distributed in the range of 0.5-5 nm and was in a quasi-zero-dimensional spherical shape.After eluting Co~(2+) with EDTA,it can be used as a fluorescence probe for detecting Co~(2+).In the range of 10-500 μmol·L~(-1),the fluorescence intensity(F_0/F) has a linear relationship with the concentration of Co~(2+),and the Stern-Volmer linear regression equation can be expressed as F_0/F=1.06+(3.18×10~(-4)) C(Co~(2+)),with the correlation coefficient R~2 being 0.98.In addition,IIT/GQDs can be used for Co~(2+) detection in actual water samples.This research method provides new ideas for carbon dots in the field of environmental monitoring.

JOURNAL OF CHEMICAL ENGINEERING OF CHINESE UNIVERSITIES Vol.39 2025 Annual Editorial Index