Enhancement Of Catalytic Activity Research Articles

Reshaping the binding pocket of D-tagaturonate epimerase UxaE to improve the epimerization activity of C4-OH for enabling green synthesis of d-tagatose

d-tagatose, a rare sugar with broad applications in the food and pharmaceutical industries, can be synthesized from d-fructose by epimerases, an approach with significant biosynthesis potential. However, so far there has been only one attempt to engineer tagatose 4‑epimerase through random mutagenesis. The lack of exploration has severely restricted the application of epimerases in the industrial production of d-tagatose. The previous research primarily focused on enhancing the catalytic activity of epimerases through random mutagenesis, with limited understanding of how substrate-adjacent residues affect enzyme efficiency, which was hence the subject of this study. First, using a semi-rational design approach, after three rounds of mutagenesis and screening, the mutant (S125D/S268A/Q124E) of D-tagaturonate epimerase (UxaE) from Thermotoga neapolitana was obtained, which increased d-tagatose production efficiency by 10.8-fold compared to the wild type, with a specific activity of 1505.6 U/g, representing the highest specific activity reported for a UxaE mutant to date. Molecular dynamics simulations showed that the substitution of Ser to Asp-125 enhanced substrate-enzyme interactions, while the substitution of Glu to Gln-124 reinforced the hydrogen bond network around the catalytic residue Glu-128, further reshaping the substrate-binding pocket and enhancing catalytic activity. This study for the first time explored the enhancement of the C4 epimerization function of epimerases by reshaping their substrate-binding pockets, thereby providing a feasible route for the industrial biosynthesis of d-tagatose.

Modified Ta2O5-x prepared by NaBH4 reduction for enhance its photocatalytic activity

The generation of oxygen vacancies assumes a pivotal role in the photocatalytic degradation of antibiotics. Surface oxygen vacancies serve as deterrents to the recombination of photogenerated carriers, thereby augmenting photocatalytic efficiency. In this work, the NaBH4 reduction technique was adopted to introduce oxygen vacancies onto the surface of Ta2O5-x, thus enhancing its photocatalytic powers. Remarkably, the photocatalytic activity of the modified Ta2O5-x-0.5 M samples exhibited significant improvement upon treatment with NaBH4 solution at varied concentrations. Characterization of the modified Ta2O5-x samples was conducted using a suite of techniques including XRD, FT-IR, UV–vis DRS, ESR, XPS, and EPR. Notably, the EPR spectrum provided compelling evidence of the presence of oxygen vacancies, affirming their existence on the surface of the modified Ta2O5-x samples. To further corroborate the formation of oxygen vacancies, tetracycline (TC) solution was employed as a simulated pollutant, revealing a marked enhancement in visible light catalytic activity through experimental observations. The findings elucidate that the defect sites engendered by oxygen vacancies primarily enhance the efficiency of electron-hole pair separation and facilitate greater absorption of visible light, thereby amplifying photocatalytic activity. The modification of Ta2O5-x samples by NaBH4 reduction predominantly facilitates the introduction of oxygen vacancies on the surface, consequently bolstering photocatalytic performance. This exemplifies a noteworthy approach for significantly enhancing the photocatalytic activity of Ta2O5-x, providing valuable insights for future design strategies.

Zwitterionic Polyelectrolyte Complex Vesicles Assembled from Homopoly(2-Oxazoline)s as Enzyme Catalytic Nanoreactors for Potent Anti-Tumor Efficiency.

Enzymes are known for their remarkable catalytic efficiency across a wide range of applications. Here, we present a novel and convenient nanoreactor platform based on zwitterionic polyelectrolyte complex vesicles (PCVs), assembled from oppositely charged homopoly(2-oxazoline)s, facilitating enzyme immobilization. We show remarkable enhancements in catalytic activity and stability by encapsulation of lipase as a model enzyme. Even as the temperature rises, the performance of the lipase remains robust. Further, the structural characteristics of PCVs, including hollow architecture and semipermeable membranes, endow them with unique advantages for enzyme cascade reactions involving glucose oxidase (GOx) and horseradish peroxidase (HRP). A decline in catalytic efficiency is shown when the enzymes are individually loaded and subsequently mixed, in contrast to the coloaded GOx-HRP-PCV group. We demonstrate that the vesicle structures establish confined environments where precise enzyme-substrate interactions facilitate enhanced catalytic efficiency. In addition, the nanoreactors exhibit excellent biocompatibility and efficient anti-tumor activity, which hold significant promise for biomedical applications within enzyme-based technologies.

Tailoring oxygen vacancies by synergy of dual metal cations in LaCo0.8M0.2O3 (M = Cu, Ni, Fe, Mn) towards catalytic oxidation of toluene

Enhancing the catalytic performance of transition metal oxide catalysts is prerequisite for the efficient catalytic oxidation of VOCs. Here the B-site partially substituted LaCoO3 (LaCo0.8M0.2O3, M = Cu, Ni, Fe and Mn) catalysts was synthesized for the catalytic oxidation of toluene. Among these catalysts, LaCo0.8Ni0.2O3 catalyst exhibits remarkable catalytic performance for toluene with T50 = 226 °C and T90 = 239 °C at an initial toluene concentration of 1000 ppm, whose T50 (and T90) reduced by 13 °C (and 34 °C) compared with that of LaCoO3. Confirmed by BET, XPS, and EPR characterizations, Ni substitution improves the specific surface area, Co3+/Co2+ ratio, Oads/Olatt ratio, and oxygen vacancies concentration. This improvement indicates the improvement of adsorption and activation of reactant, mobility of oxygen species, thereby contributing to the superior catalytic performance in toluene oxidation. The B-site of LaCoO3 occupied by dual cations caused the lattice distortion and formation of oxygen vacancies due to the ionic radii difference between Co and Ni cations. Moreover, the apparent activation energy of LaCo0.8Ni0.2O3, as the determining factor for the catalytic oxidation rate, was remarkably reduced. Our findings confirmed the synergy effect of Co and Ni cations at B-site on the enhancement of catalytic activity, which provides a promising strategy for oxygen vacancy engineering.

Antimicrobial framework nucleic acid‐based DNAzyme cluster with high catalytic efficiency

AbstractBACKGROUNDHydroxyl radical‐mediated materials primarily liberate more reactive and acutely lethal hydroxyl radical (•OH) and act as potent bactericidal antibiotics, for example H2O2. Hydroxyl radical possess higher tendency than that of H2O2 to attack various biological molecules such as DNA, proteins and iron–sulfur clusters, and impair their proper functioning, actively leading to strongly potent bactericidal effect. To acquire the desired antimicrobial effect, high concentration of H2O2 is required that has found medically harmful to healthy tissues of humans.RESULTSWe herein report framework nucleic acid‐regulated DNAzyme cluster (FDC) – that is, peroxidase‐like hemin‐bound G‐quadruplex (G4/H) DNAzyme – to amplify the catalytic reduction potential of G4/H complex, leading to high conversion rate of H2O2 to more reactive hydroxyl radical that potentially shows the same antibacterial efficiency at lower and safer H2O2 concentration. Specifically, we have grafted multiple copies of DNAzymes outside framework nucleic acid (FNA) to successively achieve 3–9 orders of magnitude enhancement in catalytic activity and antibacterial efficiency of FDC.CONCLUSIONOur designed FDC has successfully alleviated H2O2 toxicity and increased its efficiency as antibacterial material, as FDC amplified the catalytic reduction potential of G4/H DNAzyme, leading to high conversion rate of H2O2 to more reactive •OH that potentially shows the same antibacterial efficiency at lower and safer H2O2 concentration. © 2024 Society of Chemical Industry (SCI).

Tailoring the interfacial electron redistribution of ball-in-ball structured CuO-Co3O4 nanocomposites for synergistic enhancement in hydrolytic dehydrogenation of ammonia borane

Construction of high-efficiency and affordable catalysts for hydrogen production from hydrolysis of ammonia borane is highly desirable, but significant challenges still exist. In this study, a series of ball-in-ball hollow structured CuO-Co3O4 nanocomposites with varied Cu/Co molar ratio were constructed via simple solvothermal method combined with a post-calcination. The CuO-Co3O4 composite featuring a Cu/Co molar ratio of 1: 2 displayed the highest catalytic efficiency, achieving a turnover frequency (TOF) value of 25.0 molH2 molcat.−1 min−1 for AB hydrolysis. An evident synergistic enhancement in catalytic activity was confirmed between CuO and Co3O4. Experimental and theoretical researches uncovered that the enhancement of activity is originated from the electron transfer between Cu and Co ingredients, which is beneficial for the adsorption and activation of H2O and ammonia borane. In addition, the DFT calculations results revealed that the actual active sites for AB hydrolysis in CuO-Co3O4 composite catalyst is the Co site. These findings should provide some insightful recommendations for designing robust and cost-effective composite catalysts for the hydrolytic dehydrogenation of ammonia borane.

Metal-Ligand Cooperation with Thiols as Transient Cooperative Ligands: Acceleration and Inhibition Effects in (De)Hydrogenation Reactions.

ConspectusOver the past two decades, we have developed a series of pincer-type transition metal complexes capable of activating strong covalent bonds through a mode of reactivity known as metal-ligand cooperation (MLC). In such systems, an incoming substrate molecule simultaneously interacts with both the metal center and ligand backbone, with one part of the molecule reacting at the metal center and another part at the ligand. The majority of these complexes feature pincer ligands with a pyridine core, and undergo MLC through reversible dearomatization/aromatization of this pyridine moiety. This MLC platform has enabled us to perform a variety of catalytic dehydrogenation, hydrogenation, and related reactions, with high efficiency and selectivity under relatively mild conditions.In a typical catalytic complex that operates through MLC, the cooperative ligand remains coordinated to the metal center throughout the entire catalytic process, and this complex is the only catalytic species involved in the reaction. As part of our ongoing efforts to develop new catalytic systems featuring MLC, we have recently introduced the concept of transient cooperative ligand (TCL), i.e., a ligand that is capable of MLC when coordinated to a metal center, but the coordination of which is reversible rather than permanent. We have thus far employed thiol(ate)s as TCLs, in conjunction with an acridanide-based ruthenium(II)-pincer catalyst, and this has resulted in remarkable acceleration and inhibition effects in various hydrogenation and dehydrogenation reactions. A cooperative thiol(ate) ligand can be installed in situ by the simple addition of an appropriate thiol in an amount equivalent to the catalyst, and this has been repeatedly shown to enable efficient bond activation by MLC without the need for other additives, such as base. The use of an ancillary thiol ligand that is not fixed to the pincer backbone allows the catalytic system to benefit from a high degree of tunability, easily implemented by varying the added thiol. Importantly, thiols are coordinatively labile enough under typical catalytic conditions to leave a meaningful portion of the catalyst in its original unsaturated form, thereby allowing it to carry out its own characteristic catalytic activity. This generates two coexisting catalyst populations─one that contains a thiol(ate) ligand and another that does not─and this may lead to different catalytic outcomes, namely, enhancement of the original catalytic activity, inhibition of this activity, or the occurrence of diverging reactivities within the same catalytic reaction mixture. These thiol effects have enabled us to achieve a series of unique transformations, such as thiol-accelerated base-free aqueous methanol reforming, controlled stereodivergent semihydrogenation of alkynes using thiol as a reversible catalyst inhibitor, and hydrogenative perdeuteration of C═C bonds without using D2, enabled by a combination of thiol-induced acceleration and inhibition. We have also successfully realized the unprecedented formation of thioesters through dehydrogenative coupling of alcohols and thiols, as well as the hydrogenation of organosulfur compounds, wherein the cooperative thiol serves as a reactant or product. In this Account, we present an overview of the TCL concept and its various applications using thiols.

In situ visualizing reveals potential drive of lattice expansion on defective support toward efficient removal of nitrogen oxides

As a sustainable and promising approach of removing of nitrogen oxides (NOx), catalytic reduction of NOx with H2 is highly desirable with a precise understanding to the structure-activity relationship of supported catalysts. In particular, the dynamic evolution of support at microscopic scale may play a critical role in heterogeneous catalysis, however, identifying the in situ structural change of support under working condition with atomic precision and revealing its role in catalysis is still a grand challenge. Herein, we visually capture the surface lattice expansion of WO3-x support in Pt-WO3-x catalyst induced by NO in the exemplified reduction of NO with H2 using in situ transmission electron microscopy and first reveal its important role in enhancing catalysis. We find that NO can adsorb on the oxygen vacancy sites of WO3-x and favorably induce the reversible stretching of W-O-W bonds during the reaction, which can reduce the adsorption energy of NO on Pt4 centers and the energy barrier of the rate-determining step. The comprehensive studies reveal that lattice expansion of WO3-x support can tune the catalytic performance of Pt-WO3-x catalyst, leading to 20% catalytic activity enhancement for the exemplified reduction of NO with H2. This work reveals that the lattice expansion of defective support can tune and optimize the catalytic performance at the atomic scale.

Enhancement of catalytic activity in CO2 methanation in Ni-based catalysts supported on delaminated ITQ-6 zeolite

Ni-based catalysts supported on delaminated ITQ-6 zeolite with different Si/Al ratios, 30 and ∞, were tested in the methanation of CO2 and CO. ITQ-6 supports exhibited high surface areas (>590 m2/g), and the catalysts based on them presented elevated CO2 and CO conversion values, turnover frequencies (TOF), and CH4 selectivity (>90 %). Comparing ITQ-6 catalyst and its precursor ferrierite (FER)-based catalyst, H2-chemisorption results confirmed higher metallic dispersion for the former, which resulted in improved H2 uptake and efficient interaction of reaction intermediates via the associative pathway. Combined kinetic studies indicated that their higher available metallic surface contributed to lower apparent activation energies towards CH4 formation, accounting for the higher selectivity values. A 15 wt% Ni-based catalyst supported on ITQ-6 zeolite (Si/Al = 30) exhibited catalytic results (XCO2 = 79 % y SCH4 = 98 %) comparable or even superior to some of the best zeolite-based catalysts reported so far.

Marine Bacillus haynesii chitinase: Purification, characterization and antifungal potential for sustainable chitin bioconversion

The development of chitinase tailored for the bioconversion of chitin to chitin oligosaccharides has attracted significant attention due to its potential to alleviate environmental pollution associated with chemical conversion processes. In this present investigation, we purified extracellular chitinase derived from marine Bacillus haynesii to homogeneity and subsequently characterized it. The molecular weight of BhChi was approximately 35 kDa. BhChi displayed its peak catalytic activity at pH 6.0, with an optimal temperature of 37 °C. It exhibited stability across a pH range of 6.0–9.0. In addition, BhChi showed activation in the presence of Mn2+ with the improved activity of 105 U mL−1. Ca2+ and Fe2+ metal ions did not have any significant impact on enzyme activity. Under the optimized enzymatic conditions, there was a notable enhancement in catalytic activity on colloidal chitin with Km of 0.01 mg mL−1 and Vmax of 5.75 mmol min−1. Kcat and catalytic efficiency were measured at 1.91 s−1 and 191 mL mg−1 s−1, respectively. The product profiling of BhChi using thin layer chromatography and Mass spectrometric techniques hinted an exochitinase mode of action with chitobiose and N-Acetyl glucosamine as the products. This study represents the first report on an exochitinase from Bacillus haynesii. Furthermore, the chitinase showcased promising antifungal properties against key pathogens, Fusarium oxysporum and Penicillium chrysogenum, reinforcing its potential as a potent biocontrol agent.

Developing Covalent Organic FrameworkBiocatalysts through Enzyme Encapsulation.

Utilizing covalent organic frameworks (COFs) as porous supports to encapsulate enzyme represents an advanced strategy for constructing COFs biocatalysts, which has inspired numerous interests across various applications. As the structural advantages including ultrastable covalent-bonded linkage, tailorable pore structure, and metal-free biocompatibility, the resultant enzyme-COFs biocatalysts showcase functional enhancement in catalytic activity, chemical stability, long-term durability, and recyclability. This Concept describes the recent advances in the methodological strategies for engineering the COFs biocatalysts, with specific emphasis on the pore entrapment and in situ encapsulation strategies. The structural advantages of the COFs hybrid biocatalysts for organic synthesis, environment- and energy-associated applications are also canvassed. Additionally, the remaining challenges and the forward-looking directions in this field are also discussed. We believe that this Concept can offer useful methodological guidance for developing active and robust COFs biocatalysts.

Enhancing catalytic activity of CuCoFe-layered double oxide towards peroxymonosulfate activation by coupling with biochar derived from durian peel for antibiotic degradation: The role of C=O in biochar and underlying mechanism of built-in electric field

CuCoFe-LDO/BCD was successfully synthesized from CuCoFe-LDH and biochar derived from durian shell (BCD). Ciprofloxacin (CFX) degraded more than 95% mainly by O2•− and 1O2 in CuCoFe-LDO/BCD(2/1)/PMS system within 10 min with a rate constant of 0.255 min−1, which was 14.35 and 2.66 times higher than those in BCD/PMS and CuCoFe-LDO/PMS systems, respectively. The catalytic system exhibited good performance over a wide pH range (3–9) and high degradation efficiency of other antibiotics. Built-in electric field (BIEF) driven by large difference in the work function/Fermi level ratio between CuCoFe-LDO and BCD accelerated continuous electron transfer from CuCoFe-LDO to BCD to result in two different microenvironments with opposite charges at the interface, which enhanced PMS adsorption and activation via different directions. As a non-radical, 1O2 was mainly generated via PMS activation by C=O in BCD. The presence of C=O in BCD resulted in an increase in atomic charge of C in C=O and redistributed the charge density of other C atoms. As a result, strong adsorption of PMS at C atom in C=O and other C with a high positive charge was favorable for 1O2 generation, whereas an enhanced adsorption of PMS at negatively charged C accounted for the generation of •OH and SO4•−. After adsorption, electrons in C of BCD became deficient and were fulfilled with those transferred from CuCoFe-LDO driven by BIEF, which ensured the high catalytic activity of CuCoFe-LDO/BCD. O2•−, on the other hand, was generated via several pathways that involved in the transformation of •OH and SO4•− originated from PMS activation by the transition of metal species in CuCoFe-LDO and negatively charged C in BCD. This study proposed a new idea of fabricating a low-cost metal-LDH and biomass-derived catalyst with a strong synergistic effect induced by BIEF for enhancing PMS activation and antibiotic degradation.

Enhanced piezocatalytic and piezo-photocatalytic dye degradation via S-scheme mechanism with photodeposited nickel oxide nanoparticles on PbBiO2Br nanosheets

The fabrication of an S-scheme heterojunction demonstrates as an efficient strategy for achieving efficient charge separation and enhancing catalytic activity of piezocatalysts. In this study, a new S-scheme heterojunction was fabricated on the PbBiO2Br surface through the photo-deposition of NiO nanoparticles. It was then employed in the piezoelectric catalytic degradation of Rhodamine B (RhB). The results demonstrate that the NiO/PbBiO2Br composite exhibits efficient performance in piezocatalytic RhB degradation. The optimal sample is the NiO/PbBiO2Br synthesized after 2 h of irradiation, achieving a RhB degradation rate of 3.11 h−1, which is 12.4 times higher than that of pure PbBiO2Br. Simultaneous exposure to visible light and ultrasound further increases in the RhB degradation rate, reaching 4.60 h−1, highlighting the synergistic effect of light and piezoelectricity in the NiO/PbBiO2Br composite. A comprehensive exploration of the charge migration mechanism at the NiO/PbBiO2Br heterojunction was undertaken through electrochemical analyses, theoretical calculations, and in-situ X-ray photoelectron spectroscopy analysis. The outcomes reveal that p-type semiconductor NiO and n-type semiconductor PbBiO2Br possess matching band structures, establishing an S-scheme heterojunction structure at their interface. Under the combined effects of band bending, interface electric fields, and Coulomb attraction, electrons and holes migrate and accumulate on the conduction band of PbBiO2Br and valence band of NiO, respectively, thereby achieving effective spatial separation of charge carriers. The catalyst’s synergistic photo-piezoelectric catalysis effect can be ascribed to its role in promoting the generation and separation of charge carriers under both light irradiation and the piezoelectric field. The results of this investigation offer valuable insights into the development and production of catalytic materials that exhibit outstanding performance through the synergy of piezocatalysis and photocatalysis.

Exploiting Interfacial ZnO-Cu Nanocomposites in Metal–Organic Framework Derived Catalysts: Enhancement of Catalytic Activity for CO2 Hydrogenation

Exploiting Interfacial ZnO-Cu Nanocomposites in Metal–Organic Framework Derived Catalysts: Enhancement of Catalytic Activity for CO₂ Hydrogenation

Unique construction of hierarchical PANI–based nanofibrous network for boosting water electrolysis through highly efficient utilization of Pt nanocatalyst

Enhancing catalytic activity of Pt and designing rational structure of catalytic layer (CL) are effective strategies for improving the performance of proton exchange membrane water electrolysis (PEMWE) with lower Pt loading. Herein, a hierarchical nanostructured CL based on co–doped carbon, sulfonated polyaniline (PANI) nanofibrous network and Pt nanoparticles is constructed on carbon cloth by layer–by–layer in–situ growth method. The N/P/S co–doped carbon interlayer derived from PANI can promote the growth of sulfonated PANI nanofibers. The in–situ grown Pt nanoparticles is anchored by sulfonated PANI, achieving uniform and stable distribution as well as altered electronic structure for improved catalytic activity. The unique CL greatly improves the electrochemical surface area and provides interconnected pathways. The as–prepared cathode exhibits an overpotential of 23 mV at 10 mA cm−2, indicating excellent hydrogen evolution performance. Furthermore, the PEMWE device with above–mentioned cathode achieves an excellent performance of 1.771 V @ 2 A cm−2 with low Pt loading of 0.07 mg cm−2, which is comparable to that of the conventional cathode with 14 times higher Pt loading of 1 mg cm−2. Our strategy of designing hierarchical nanostructured CL provides a feasible approach to lower the consumption of Pt without performance loss for further industrialization of PEMWE.

Enhancing catalytic activity through self-assembled hydrogen-bonded organic framework-based catalysts at liquid/liquid interface for 4-nitrophenol reduction and energy challenges in methanol fuel cell

Hydrogen-bonded organic frameworks (HOFs) are pure organic framework structures endowed with appropriate flexibility and porosity, which have attracted special attention in the field of energy and water, air, and soil remediation. In this study, six HOF-based materials were synthesized as thin film at the liquid/liquid (toluene/water) interface and characterized by FT-IR, Raman, UV–Vis, PXRD, ICP, AFM, SEM, TGA, and BET techniques. The self-assembled HOF-based thin films were employed as catalysts for the 4-nitrophenol removal from water medium and, for the first time, for methanol oxidation of fuel cell, with satisfying results. Simultaneous in situ catalyst formation and 4-nitrophenol reduction occurred in the case of Pt(0)@HOF thin film, but an extraordinary removal (not reduction) occurred in the presence of Pt(0)-trimesic acid thin film by formation of a new HOF from trimesic acid and 4-nitrophenol. Successful reduction of 4-nitrophenol occurred also in the presence of freshly prepared Pt(0)-trimesic acid, Pt(0)-melamine and Pt(0)@HOF catalysts (ex situ strategy). The chemical and thermal stability of HOF structure was improved by the interpenetration of ZIF-8 crystal structure, by increasing the hydrogen bonding and π-π stacking in the presence of 2-methylimidazole. The interpenetration of ZIF-8 to the crystal structure of HOF caused a significant decrease of the pore diameter of the structure. These pores acted as specific sites for the guest molecules, and their dimensions did not permit 4-nitrophenol to penetrate into the cavity of structures whereas allowed methanol penetration into these cavities due to its smaller size.

Enhancing catalytic activity of TiO2 nanoparticles through acid treatment in Eosin-Y sensitized photohydrogen evolution reaction system

Light-driven water splitting has gained increasing attention as an eco-friendly method for hydrogen production. There is a pressing need to enhance the performance of catalysts for the commercial viability of this reaction. Many methods have been proposed to improve catalyst performance; however, an economical and straightforward approach remains a priority. This paper presents an uncomplicated technique called acid treatment, which augments the catalytic performance of nanoparticles. The method promotes a change in the catalytic reactivity by causing a deficit in electron density of Ti and O on the surface of TiO2 nanoparticles without altering their size, morphology, or crystal structure. In the Eosin Y sensitized photocatalytic hydrogen production system, nitric acid treated TiO2 (16.95 μmol/g) exhibited 1.5 times the hydrogen production compared to bare TiO2 (11.15 μmol/g).

Design highly effective B or N doped mesoporous carbon fibers catalysts for I3-/I- redox couple regeneration in carbon-based dye-sensitized solar cells

Construction of mesoporous structure and improving the conductivity of carbon counter electrode are feasible paths to enhance the catalytic activity in dye-sensitized solar cells (DSCs) toward the I3-/I- redox couple regenerating (IRR). Herein, mesoporous carbon fiber (PCf) has been first synthesized and the DSCs using PCf counter electrode results in a power conversion efficiency (PCE) of 7.12%, significantly surpassing the PCE of 6.01% generated by the DSCs with carbon fiber (Cf) counter electrode without mesoporous structure. Additionally, doping with heteroatoms B or N can further enhance the catalytic performance of PCf. Consequently, B or N doped Cf (BPCf or NPCf) counter electrode-based DSCs achieve high PCE values of 8.43% and 7.96%, respectively, demonstrating PCE improvements of 40.3% and 32.4%. This enhancement in catalytic activity for IRR in DSCs can be first attributed to the increased specific surface area of Cf which can provide more catalytic activated sites. Meanwhile, the enhanced conductivity of PCf by heteroatoms B or N doping is also an important factor for the improved catalytic activity. This work is expected to provide potential path to enhanced the catalytic activity of carbon counter electrode in DSCs toward IRR.

A striking exploration of defect engineering in HfS2, HfSe2, and janus HfSSe through ab initio analysis for HER catalysis application

The present study emphasizes the enhancement in catalytic activity due to the formation of vacancies using dispersion corrected density functional theory. We observed that without vacancy formation, in general the edge site is an active site for hydrogen adsorption, while the lowest Gibbs free energy (ΔGH) is found to be for Janus HfSSe at the S-edge site. Furthermore, interestingly, due to the hindrance of the edge site, it facilitates only the Volmer-Heyrovsky reaction rather than the Volmer-Tafel. Among the mono vacancies, the Hafnium mono vacancy shows the lowest adsorption energy.We observed a competition between the evolution of H2S and H2 gas in the case of HfS2-VHf, whereas in the case of defected Janus and HfSe2, due to the presence of Se layers, we observed no competitiveness with H2S or H2Se gas with hydrogen gas. These defected materials exhibit lower reactional Gibbs free energy than a pristine monolayer due to its metallic nature. We observed that Hafnium vacancy enhances the HER activity, and pave the way for dominating Volmer-Heyrovsky reaction.

The effect of magnesium embedded into NiAPO-11 zeolite on enhancing its catalytic performance of 2-butene skeletal isomerization

The distribution of acidic sites in molecular sieves has a decisive impact on catalytic skeletal isomerization of 2-butene. Accurately adjusting the acidic site to meet high selectivity and stability of the catalyst is crucial. Herein, magnesium embedding into NiAPO-11 zeolite was prepared by static hydrothermal method. The introduction of magnesium increased the proportion of weak Brønsted acid, resulting in a significant enhancement of catalytic activity. When the molar ratio of magnesium to aluminum oxide was 0.2:1, Mg-NiAPO-11 exhibited the best catalytic performance with the conversion of 2-butene being 65.06 % and the selectivity of isobutene being 71.02 %, which was comparable or even better than those reported previously. Furthermore, Mg-NiAPO-11 had good stability. The conversion of 2-butene only decreased by 3 %, while the selectivity of isobutene increased by 8 % during the 72-h reaction. Obviously, it was found that a small amount of carbon deposition led to an increase in the relative amounts of weak Brønsted acid, which resulting in an increase in the selectivity of isobutene. Our work put forward an effective strategy for accurately tuning the acidic sites of molecular sieves to effectively catalyze 2-butene to isobutene.