Enhancement Of Catalytic Activity Research Articles

Exploring Pt-Cu synergistic effects on porous SiO2 support with different Pt loadings for low-temperature oxidation of CO and C3H6

To address the high cost of noble metals, this study aims to optimize Pt loading and the synergistic effect of Cu on porous SiO2 support for low-temperature oxidation of CO and C3H6. A simulated test bench system was used to evaluate the performance of PtxCu1/SiO2 (where x= 0.3, 0.5, 0.7, and 1 wt%), Cu1/SiO2 and Ptx/SiO2 (where x= 0.5 and 1 wt%) catalysts with varying Pt loadings. Comprehensive characterization, including BET, XRD, SEM, TEM, and XPS was conducted to assess particle size, structure, and surface morphology. The effects of Pt incorporation on reduction and oxidation properties were further examined using H2-TPR and CO-TPD techniques. Results demonstrated a significant enhancement in catalytic activity with the addition of Cu confirming a synergistic interaction between Pt and Cu. This synergy was particularly pronounced in lower Pt loadings, where PtxCu1/SiO2 composites outperformed Ptx/SiO2 in catalytic activity. Pt addition reduced the particle size, which resulted in the creation of PtCu alloy, with 1 and 0.7 % wt Pt loading exhibiting comparable effects in CO conversion and 0.7 % Pt loading exhibiting better activity at higher temperatures in C3H6 oxidation indicating that catalytic activity was maintained even with a reduced Pt loading. Additionally, minimal difference in activity for C3H6 oxidation was observed among PtxCu1/SiO2 catalysts with 0.7, 0.5, and 0.3 wt% Pt loadings as indicated by T50 and T80 values. Reducing Pt loading from 0.7 wt% had minimal impact on catalytic efficiency for C3H6 oxidation with catalysts maintaining high activity. 0.7 wt% Pt loadings provide sufficient active sites for effective CO and HC oxidation. The enhanced catalytic activity and stability of bimetallic catalysts over monometallic Cu/SiO2 and Pt/SiO2 result from the simultaneous presence of active sites created by the synergetic effect of PtCu alloy formation with optimal ratio and well-optimized surface. These findings demonstrate the potential to optimize Pt usage without compromising catalytic performance, offering a cost-effective approach to catalyst design.

Visible light-induced photocatalytic oxidation of gaseous ammonia on C surface-coated N-TiO2 catalyst: synthesis, properties and mechanism

This paper explores an eco-friendly and efficient photocatalytic oxidation (PCO) technology aimed at converting NH3 into N2, which holds considerable importance for environmental conservation and human well-being. Building upon previous investigations of N-TiO2 catalysts, the research group successfully synthesized an N-TiO2 catalyst featuring a carbon layer on its surface via mechanical mixing followed by calcination at 400 °C (denoted as C/N-TiO2(1), 1 represents the molar ratio of N and Ti). The analysis concentrated on the influence of C content on the PCO efficiency of NH3, revealing a peak performance correlated with increasing C levels. Notably, the C/N-TiO2(1) catalyst with 3.0 wt% C exhibited remarkable catalytic performance, achieving a conversion rate of 94 % and selectivity of 98 %. The enhancement of catalytic activity and selectivity is primarily attributed to the co-doping of C and N elements. Experimental results indicate that doping with N alone effectively suppresses the recombination of photogenerated carriers under visible light. Furthermore, the simultaneous doping of C and N significantly reduces the band gap energy of TiO2 (3.18 to 2.90 eV), thereby broadening its photoresponse range. Concurrently, more Ov (Oxygen vacancy) are formed under visible light irradiation, which enhances the PCO performance. More importantly, more acidic sites are introduced to improve the catalyst’s adsorption capacity for NH3. Additionally, the impact of various reaction components on the PCO capability of the 3.0 wt% C/N-TiO2(1) catalyst is examined further. The findings indicate that oxygen anion radicals produced from O2 play a critical role in facilitating NH3-PCO. However, the presence of CO2 and extra H2O could hinder the approach of NH3 molecules to the active sites and decrease the longevity of photogenerated ·OH, consequently reducing catalytic effectiveness. This research introduces fresh insights and optimization approaches for enhancing the activity, selectivity, and stability of catalysts.

Rational Design for Enhancing Cellobiose Dehydrogenase Activity and Its Synergistic Role in Straw Degradation.

Addressing the demand for efficient biological degradation of straw, this study employed rational design coupled with structural biology and enzyme engineering techniques to enhance the catalytic activity of cellobiose dehydrogenase (PsCDH, CDH form Pycnoporus sanguineus). By predicting and modifying the active site and key amino acids of PsCDH, several CDH immobilized enzyme preparations with higher catalytic activities were successfully obtained. The excellent mutant T1 (C286Y/A461H/F464R) exhibited a 2.7-fold increase in enzyme activity compared to the wild type. Simulated calculations indicated that the enhancement of catalytic activity was primarily due to the formation of additional intermolecular interactions between CDH and the substrate, as well as the enlargement of the substrate pocket to reduce steric hindrance effects. Additionally, molecular dynamics simulation analysis revealed a potential correlation between structural stability and enzyme activity. When PsCDH was added to a multienzyme synergistic straw degradation system, the cellulose degradation rate increased by 1.84-fold. Moreover, mutant T1 further increased the degradation of lignocellulose in the mixed system. This study provides efficient enzyme sources and modification strategies for the high-efficiency biological conversion of straw and unconventional feedstock degradation, thereby possessing significant academic value and application prospects.

Computer-Aided Flexible Loops Engineering of Glutamate Dehydrogenase for Asymmetric Synthesis of Chiral Pesticides l-phosphinothricin.

The access to the enantiopure noncanonical amino acid l-phosphinothricin (l-PPT) by applying biocatalysts is highly appealing in organic chemistry. In this study, a NADH-dependent glutamate dehydrogenase from Lachnospiraceae bacterium (LbGluDH) was chosen for the asymmetric synthesis of l-PPT. Three flexible loops undergoing big conformational shifts during the catalysis were identified and rationally engineered following the initial mutagenesis. The enzyme's specific activity toward the key precursor of l-PPT, 2-oxo-4-[(hydroxy) (methyl) phosphinyl] butyric acid (PPO), was improved from negligible to 9 U/mg, and the Km value was reduced to 17 mM. The computational analysis showed that the modified loops broadened the enzyme's narrow tunnels, allowing the substrate to access the binding pocket and get closer to the crucial residue D165, thereby enhancing the catalytic process. Utilizing the variant as the catalyst, the preparation of l-PPT achieved a 100% conversion rate within 60 min, coupled with a stereoselectivity exceeding 99.9%, demonstrating its practical capacity for industrial application. Similar enhancement in catalytic activity was obtained applying the same strategy to a typical NADH-dependent GluDH from Pyrobaculum islandicum (PisGluDH), indicating the effectiveness of our strategy for the protein engineering of GluDHs targeted to the biosynthesis of unnatural compounds.

Computationally Driven Discovery and Characterization of SIRT3-Activating Compounds that Fully Recover Catalytic Activity under NAD+ Depletion

Many chronic, age-related disorders could be mitigated by enhancing the activity of enzymes that regulate biochemical signaling pathways, but all known modes of enzyme activation rely on allosteric binding sites, which have only been identified in less than 10% of proteins. Sirtuins (SIRT1-7) are nicotinamide adenine dinucleotide (NAD+)-dependent deacylases playing critical roles in lifespan and age-related diseases. The physiological importance of sirtuins and the reduction in their catalytic activity with the age-related decline in NAD+ levels have stimulated intense interest in designing sirtuin-activating compounds; however, except for substrate-specific allosteric SIRT1 activators, methodologies for rational design of sirtuin-activating compounds are lacking. Here, we introduce methods for the activation of such enzymes that do not rely on allosteric binding sites, and we demonstrate their successful application to the discovery of first-in-class activators of sirtuin enzymes. We establish how all-atom simulations of an enzyme’s active site under the potential of a small molecule modulator can be used to identify molecular properties that achieve desired changes in local enzyme conformational degrees of freedom conducive to the enhancement of catalytic activity. We apply computational high-throughput screening based on this biophysical model for activation of sirtuin enzymes to the major mitochondrial sirtuin SIRT3, which plays a critical role in age-related disorders but does not have a known allosteric site; we thereby identify first-in-class, nonallosteric activators of this enzyme. These compounds are the first reported steady-state activators of the major mitochondrial sirtuin enzyme, and they operate according to a mode of action not shared by any existing drug. Two such compounds can almost double the catalytic efficiency of SIRT3 with respect to NAD+, thus compensating for the loss in SIRT3 activity that occurs due to the age-related decline in NAD+, and they may be developed for therapeutic applications to combat multiple types of age-related disorders. These discoveries establish a foundation for the development of a new class of drugs that function through the activation of enzymes by modulation of local conformational ensembles. Published by the American Physical Society 2024

Maltose gradient-induced biosensor-based high-throughput screening for directed evolution of maltogenic amylase from Bacillus stearothermophilus

Maltogenic amylase is a starch-hydrolyzing enzyme commonly used in bread baking and high-concentration maltose syrup production. However, low catalytic activity limits its industrial application. Improving catalytic activity based on molecular modification and directed evolution requires a High-Throughput Screening (HTS) method. In this study, a maltose gradient-induced (MaGI) biosensor was designed and applied for the directed evolution of maltogenic amylase AmyM, showing a good positive correlation between enzyme activity and fluorescence. The MaGI biosensor detected maltose and maltogenic amylase activity efficiently and specifically. Two mutants, Q440N and S442N/Q661L, were identified through the screening of 3000 mutants using the MaGI biosensor, showing a significant increase in catalytic activity of 35.56 % and 24.51 %, respectively, compared to the wild-type. Meanwhile, the t1/2 of Q440N and S442N/Q661L at 60 °C increased by 58.53 % and 66.66 %, respectively. In industrial applications, the enhancement of catalytic activity and stability is conducive to improving production efficiency and reducing costs. MD simulation has found that when modifying multidomain enzymes, distal mutations can enhance catalytic activity. In conclusion, the developed MaGI biosensor is a promising tool for high-throughput and specific detection of maltose.

Thermally Stable High-Entropy Layered Double Hydroxides for Advanced Catalysis.

Layered double hydroxides (LDHs), especially high-entropy LDHs (HE-LDHs), have gained increasing attention. However, HE-LDHs often possess poor thermal stability, restricting their applications in thermo-catalysis. Herein, a novel complexing nucleation method is proposed for engineering HE-LDHs with enhanced thermal stability. This approach precisely controls the nucleation of metal ions with different solubility products, achieving homogeneous nucleation and effectively mitigating phase segregation and transformation at elevated temperatures. The prepared HE-LDH sample demonstrated exceptional thermal stability at temperatures up to 300°C, outperforming all previously reported LDHs. Importantly, these HE-LDHs preserve both Lewis and Brønsted acidic sites, enabling the 100% removal of aromatic sulfides and alkaline nitrogen compounds from fuel oils in thermo-catalytic oxidation reactions. Experimental and characterization findings reveal that the metal-hydroxide bonds in the prepared HE-LDHs are strengthened by associated hydroxyl groups, inducing negative thermal expansion and augmenting the presence of acidic sites, thereby ensuring structural stability and enhancing catalytic activity. This study not only proposes a strategy for engineering HE-LDHs with remarkable thermal stability but also highlights potential applications of LDHs in thermo-catalysis.

Enhancement of Catalytic Activity via Inevitable Reconstruction of the Ni-Mo Interface for Alkaline Hydrogen Oxidation.

The inevitable oxidation of nickel-metal-based catalysts exposed to the air will lead to instability and poor reproducibility of a catalytic interface, which is usually ignored and greatly hinders their application for the catalysis of alkaline hydrogen oxidation. The details on the formation of a world-class nickel-based HOR catalyst Ni3-MoOx/C-500 are reported via an interfacial reconstruction triggered by passive oxidation upon air exposure. Interfacial reconstruction, initiated with various Ni-Mo metal ratios and annealing temperature, can fine-tune the Ni-Mo interface with an increased work function and a reduced d-band center. The optimized Ni3-MoOx/C exhibits a record high mass activity of 102.8mA mgNi -1, a top-level exchange current density of 76.5µA cmNi -2, and exceptional resistance to CO poisoning at 1000ppm CO for hours. The catalyzed alkaline exchange membrane fuel cell exhibits a maximum power output of 600mW cm-2 and excellent stability, ranking it as one of the most active non-precious metals HOR catalysts to date.

Durable electrocatalysts based on barium niobates doped with Ca, Fe, and Y: Enhancing catalytic activity and selectivity for oxidative coupling of methane

Effective conversion of methane into value added products such as olefins, is a major research area for the past 40 years. Electrochemical oxidative coupling of methane (E-OCM) is recently gaining attention due to its ability to control the product selectivity by oxide ion flux and applied potential. We report a new series of catalysts, Ca, Fe, and Y co-doped barium niobate perovskites (BCNFY) for E-OCM application. BCNFY perovskites show chemical stability under 4 % H2, CH4, and high CH4-O2 mixtures at high temperatures up to 900 °C. Under reducing conditions, BCNFY perovskites form excess oxygen vacancies that is supported by Nb4+/5+ oxidation state changes that help retain the crystal structure. Temperature programmed reaction (TPR) measurements under 95 % CH4:5% O2 reveal methane activation properties from 600 °C with a high C2+ selectivity of 82 % at 850 °C. TPR measurements further reveal the nature of active sites for methane activation. Cyclic voltammetry measurements show a unique relationship between product selectivity and applied potential as at applied biases close to open circuit potential, CO and H2 are the major products while at high applied biases ethylene and CO2 are the major products. Our results show the advantages of E-OCM over conventional OCM although improvements in terms of electronic conductivity of the electrode and overall current densities are required for commercial viability for these perovskite electrodes.

SnO2-x/CD-MOF S-Scheme heterostructure photocatalysts synergized by oxygen vacancies and highly porous for rhodamine B and tetracycline degradation: Process, and mechanism analysis

To enhance the performance of environmentally friendly cyclodextrin metal-organic framework (CD-MOF) materials for more effective removal of organic pollutants and wastewater treatment, also the composites underwent optimization, and the adsorption-enhanced photocatalytic mechanism was thoroughly investigated. This study presents the synthesis of novel SnO2-x/CD-MOF (SCM) photocatalysts were prepared by a simple solvothermal method, which were characterized by oxygen vacancies (OVs), high specific surface area and heterojunction. SCM exhibited outstanding photodegradation performance for rhodamine B (RhB) and tetracycline (TC) when exposed to visible light. Specifically, the RhB removal efficiency was an impressive 93.5 %, achieved with a degradation rate constant of 0.0484 min−1, while the removal efficiency of TC was 83.1 %, with a degradation rate constant of 0.0246 min−1. The photodegradation activity of SCM was predominantly influenced by ·O2-, h+, and ·OH. The mechanism of action involves three phases: adsorption, photocatalysis, and desorption-diffusion. The exceptional performance of SCM in terms of photocatalysis can be gave the credit to the synergistic effect of the high specific surface area of γ-CD-MOF and the oxygen vacancy-induced enhancement of SnO2-x catalytic activity. TC degradation intermediates and possible degradation pathways were analyzed and the toxicity of the intermediates was assessed. This study introduces a novel approach to designing CD-MOF-based photocatalysts.

Unlocking OER potential: Tailoring layered double perovskites through self-reconstruction

The sluggish rate of the anode oxygen evolution reaction (OER) is a major bottleneck for green hydrogen production, making a room-temperature alkaline water electrolyser critical to unlocking the full potential of this technology. Using a perovskite oxide as an electrochemical matrix and forming a self-assembled oxyhydroxide (OOH) layer on the surface via a self-reconstruction activation process (SRAP) is a promising strategy to enhance OER catalytic activity. However, the mechanistic details and long-term impact of SRAP, especially its relationship to catalytic activity, oxygen collection efficiency, and catalyst dissolution, are not fully understood. To address this knowledge gap, we used layered double perovskite (LDP) PrBa0·75Ca0·25Co1·5Fe0·5O5+δ(PBCCF) and PrBa0·75Ca0·25Co1·5Fe0·4Ni0·1O5+δ (PBCCFN) as model electrochemical catalysts and then triggered SRAP. Subsequently, chronoamperometry (CA), rotating ring disk electrode (RRDE) and in-situ electrochemical quartz crystal microbalance (EQCM) were used to study the effect of the Ni-doping on PBCCF SRAP in terms of catalytic activity, oxygen collection efficiency and catalyst stability. The results showed that the OER catalytic current of the LDP PBCCF and PBCCFN was enhanced via SRAP and the oxygen collection efficiency can be maintained, suggesting that the increase in catalytic current is attributed to OER catalytic activity increase rather than electrochemical catalyst dissolution. Additionally, the effect of the catalytic activity enhancement was more significant in PBCCFN. More importantly, the stability of the LDP PBCCF and PBCCFN after SRAP are higher than simple perovskite Ba0·5Sr0·5Co0·8Fe0·2O3-δ (BSCF) because of the increase in the redeposition rate. The observations suggest that using LDP PBCCF and PBCCFN as matrices followed by triggering SRAP can provide valuable insights for designing LDP based OER electrocatalysts.

Cu-TM (Mn, Fe, Ni) dual-atom vs. Pt single atom: TM atoms modulate the electronic structure of Cu sites supported on melamine aerogel to enhance the catalytic purification performance of CH3SH

Despite the high atomic utilization and unique electronic properties of single-atom catalysts (SACs), the single active site to some extent limits the rapid and stable execution of complex reactions involving multiple steps and intermediates on the SACs surface. To address this issue, dual-atom catalysts (DACs) have emerged. The specific spatial proximity enables a synergistic effect between the diatomic pairs, significantly promoting catalytic reactions, though the exact synergistic mechanisms remain to be explored. In this work, we successfully constructed Cu single-atom (Cu-MA) and CuTM (transition metal, TM = Mn, Fe, Ni) dual-atom (CuTM-MA) catalysts on the surface of melamine aerogel (MA) via the impregnation method. Additionally, single-atom catalysts with different Pt loadings (0.5 %, 1 %, and 2 %) (Pt-MA) were synthesized to compare the CH3SH decomposition activity with that of CuTM-MA. Experimental results showed that CuTM-MA significantly outperformed Cu-MA and even rivaled Pt-MA at high temperatures. Utilizing Cu K-edge XAFS, we found that the presence of TM not only enhanced the stability of Cu atoms on the MA surface, preventing aggregation at high temperatures to some extent, but also effectively modulated the electronic structure of Cu atoms, promoting electron transfer from Cu to TM, thus achieving a significant enhancement in catalytic activity.

Single-stranded DNA regulated peroxidase mimetic activity of MCOF@AuNPs for colorimetric detection of carcinoembryonic antigen

Rapid, accurate, simple and portable monitoring of carcinoembryonic antigen (CEA) in serum is important for assessing the occurrence, development, and prognosis of cancer. In this work, we developed a colorimetric method based on the peroxidase-like activity of MCOF@AuNPs functionalized by complementary sequences of CEA-specific aptamer (MCOF@AuNPs-apt*) enhancing by G-terminated CEA-specific aptamer (G-apt). The enhancement of catalytic activity depends on the increase affinity of MCOF@AuNPs-apt*-G-apt to the TMB via promoting electron transfer. Based on this strategy, we successfully detected CEA at 0.1 ng/mL with high accuracy and anti-interference ability. Importantly, combined with the smartphone app based on the smartphone app RGB color model, the results can be visualized directly without expensive equipment, which meets the demand for point of care testing of CEA. This study also explored the enhancement of catalytic activity of nanozyme by ssDNA and the application potential in aptamer biosensor.

Synergistic effect of Fe-Ru alloy and Fe-N-C sites on oxygen reduction reaction

In the pursuit of optimizing Fe-N-C catalysts for the oxygen reduction reaction (ORR), the incorporation of alloy nanoparticles has emerged as a prominent strategy. In this work, we effectively synthesized the FeRu-NC catalyst by anchoring Fe-Ru alloy nanoparticles and FeN4 single atom sites onto carbon nanotubes. The FeRu-NC catalyst exhibits significantly enhanced ORR activity and long-term stability, with a high half-wave potential of 0.89 V (vs. RHE) in alkaline conditions, and the half-wave potential remains nearly unchanged after 5000 cycles. The zinc-air battery (ZAB) assembled with FeRu-NC demonstrates a power density of 169.1 mW cm−2, surpassing that of commercial Pt/C. Density functional theory (DFT) calculations reveal that the synergistic interaction between the Fe–Ru alloy and FeN4 single atoms alters the electronic structure and facilitates charge transfer at the FeN4 sites, thereby modulating the adsorption and desorption of ORR intermediates. This enhancement in catalytic activity for the ORR process underscores the potential of this approach for refining M-N-C catalysts, providing novel insights into their optimization strategies.

Thiourea enhanced oxidase-like activity of CeO2/CuxO nanozyme for fluorescence/colorimetric detection of thiourea and glutathione

A novel fluorescence/colorimetric dual-mode sensor, based on enhancement of the oxidase-like activity of CeO2/CuxO nanozyme towards the oxidation of o-phenylenediamine (OPD) induced by thiourea (TU), has been proposed for TU detection. The catalytic activity enhancement on CeO2/CuxO can be attributed to the strong electron-donation ability of TU, which promoted hydroxyl radical generation and amplified OPD oxidization with enhanced dual-signal readout. By integrating a portable paper-chip and smartphone system, this CeO2/CuxO-OPD system achieved on-site visual colorimetric analysis of TU. The dual-mode sensor demonstrated high sensitivity and specificity in recognizing TU, with a detection limit (LOD) of 1.90 μM and a linear range (LR) 2.5–80 μM in fluorescent mode; as well as an LOD of 6.69 μM and an LR 10–250 μM in colorimetric mode. Furthermore, the CeO2/CuxO-TU-OPD system has been designed for dual-mode glutathione (GSH) detection with enhanced sensitivity, achieving an LOD of 0.19 μM and an LR 0.5–10 μM in fluorescent mode; as well as an LOD of 1.24 μM and an LR 1.25–25 μM in colorimetric mode. Additionally, GSH discrimination (fluorescent mode) was successfully achieved in different biological samples, showing good consistency with the standard method. The recoveries ranged from 96.8 % to 116.7 % in serum samples and from 97.3 % to 107.7 % in cell lysates, with RSDs less than 2 %. This work not only introduced a novel approach to enhance oxidase-like activity of nanozymes but also provided an efficient field-suitable tool for enhanced dual-mode response towards TU and GSH.

Inducing a Synergistic Effect on Ptδ+/Electron-Rich Sites via a Platinization Strategy: Generating Hyper-High Current Density in Hydrogen Evolution Reaction.

Herein, we propose a platinization strategy for the preparation of Pt/X catalysts with low Pt content on substrates possessing electron-rich sites (Pt/X: X = Co3O4, NiO, CeO2, Covalent Organic Framework (COF), etc.). In examples with inorganic and organic substrates, respectively, Pt/Co3O4 possesses remarkable catalytic ability toward HER, achieving a current density at an overpotential of 500 mV that is 3.22 times higher than that of commercial Pt/C. It was also confirmed by using operando Raman spectroscopy that the enhancement of catalytic activity was achieved after platinization of the COF, with a reduction of overpotential from 231 to 23 mV at 10 mA cm-2. Density functional theory (DFT) reveals that the improved catalytic activity of Pt/Co3O4 and Pt/COF originated from the re-modulation of Ptδ+ on the electronic structure and the synergistic effect of the interfacial Ptδ+/electron-rich sites. This work provides a rapid synthesis strategy for the synthesis of low-content Pt catalysts for electrocatalytic hydrogen production.

Crystal structure and structure-guided tunnel engineering in a bacterial β-1,4-galactosyltransferase

Lacto-N-neotetraose (LNnT), a representative oligosaccharide found in human milk, has been previously examined for its beneficial traits. However, the LNnT titer is limited by the efficient glycosyltransferase pathway, particularly with respect to the catalysis of rate-limiting steps. As data on the crystal structure of the key enzyme required for synthesizing LNnT are lacking, the synthesis of LNnT remains an uncertainty. Here, for the first time we report the three-dimensional structure of a bacterial β-1,4-galactosyltransferase, Aaβ4GalT, and analyze the critical role played by residues in its catalytic efficacy. Guided by structural insights, we engineered this enzyme to enhance its catalytic efficiency using structure-guided tunnel engineering. The mutant enzyme L5 (K155M/H156D/F157W/K185M/Q216V) so produced, showed a 50-fold enhancement in catalytic activity. Crystal structure analysis revealed that the mechanism underlying the improvement in activity was of the swing door type. The closed conformation formed by dense hydrophobic packing with Q216V-K155M widened and permitted substrate entry. Our results show that altering the tunnel conformation helped appropriately accommodate the substrate for catalysis and provide a structural basis for the modification of other glycosyltransferases.

Construction of high‐loading WO3‐x sub‐nanometer clusters via orderly‐anchored top–down strategy boost acidic hydrogen evolution

AbstractExploring a simple, rapid, and scalable synthesis method for the synthesis of high loading nonprecious metal sub‐nanometer clusters (SNCs) electrocatalysts is one of the most promising endeavors today. Herein, an orderly‐anchored top–down strategy is proposed for fabricating a new type of high loading WO3‐x SNCs on O‐functional group‐modified Ketjen black (WO3‐x‐C(O)) to balance the high loading (49.29 wt.%) and sub‐nanometer size. By optimizing the vacancy number, WO2.71‐C(O) has extremely large electrochemically active surface area (402 m2 g−1) and high turnover frequency value of 1.722 s−1 at −50 mV (vs. reversible hydrogen electrode). The overpotential of WO2.71‐C(O) reaches 22 mV at a current density of 10 mA cm−2, which is significantly better than the commercial Pt/C level (32 mV), achieving a breakthrough in the hydrogen evolution reaction (HER) catalytic activity of nonprecious metals in acidic environment. Theoretical calculations and in situ characterization show that this material allows for the enrichment of reactants (H*) and the optimization of intermediate adsorption, which leads to the enhancement of acidic HER catalytic activity.

Non‐Oxidative Dehydroaromatization of Linear Alkanes on Intermetallic Nanoparticles

There has been significant interest in developing new catalytic systems to convert linear chain alkanes into olefins and aromatics. In the case of higher alkanes (≥ C6), the production of aromatic compounds such as benzene‐toluene‐xylenes is highly desirable. However, as the length of the carbon chain increases, the dehydrogenation process becomes more complex, not only due to the challenges of C‐H activation but also the need for selectivity towards the desired products by the possibility of side reactions such as isomerization and cracking. Here, we present a detailed analysis of the dehydroaromatization of n‐hexane, n‐heptane, and n‐octane, using PtSn intermetallic nanoparticles supported on SBA‐15 as the catalyst. Through in‐situ spectroscopic and kinetic analysis, we have probed into the reaction kinetics, catalyst deactivation, and a mechanistic understanding of the dehydroaromatization process on the surface of the PtSn intermetallic nanoparticles. Introducing Sn has been shown to be crucial not only for enhancement of catalytic activity, but also for higher aromatics selectivity and stability on stream. Furthermore, the analysis of dehydroaromatization reaction rates of reactant and possible intermediates indicates that the dehydroaromatization of n‐hexane to benzene likely proceeds through initial dehydrogenation steps followed by ring closing.

Highly active manganese nitride-europium nitride catalyst for ammonia synthesis

The development of efficient catalysts for ammonia synthesis under mild conditions is critical for establishing a carbon-neutral society powered by renewable ammonia. While significant effort has been focused on Fe and Ru-based catalysts, there have been very limited studies on manganese-based catalysts for ammonia synthesis because of their low intrinsic catalytic activity. Herein, we report that the synergy between manganese nitride (Mn4N) and europium nitride (EuN) yields an ammonia synthesis rate that is 41 and 25 times higher than that of neat Mn4N and EuN, respectively. Detailed studies suggest that a [Eu-N-Mn] species at the interface of Mn4N and EuN plays a pivotal role in ammonia synthesis. Compositing of Mn4N with other rare earth metal nitrides such as LaN, PrN, and CeN also leads to a significant enhancement in catalytic activity. This work broadens the scope of advanced nitride catalysts for ammonia synthesis.