Enhancement Of Catalytic Activity Research Articles

Understanding the Distance Effect of the Single-Atom Active Sites in Fenton-Like Reactions for Efficient Water Remediation.

Emerging single-atom catalysts (SACs) are promising in water remediation through Fenton-like reactions. Despite the notable enhancement of catalytic activity through increasing the density of single-atom active sites, the performance improvement is not solely attributed to the increase in the number of active sites. The variation of catalytic behaviors stemming from the increased atomic density is particularly elusive and deserves an in-depth study. Herein, single-atom Fe catalysts (FeSA-CN) with different distances (dsite) between the adjacent single-atom Fe sites are constructed by controlling Fe loading. With the decrease in dsite value, remarkably enhanced catalytic activity of FeSA-CN is realized via the electron transfer regime with peroxymonosulfate (PMS) activation. The decrease in dsite value promotes electronic communication and further alters the electronic structure in favor of PMS activation. Moreover, the two adjacent single-atom Fe sites collectively adsorb PMS and achieve single-site desorption of the PMS decomposition products, maintaining continuous PMS activation and contaminant removal. Moreover, the FeSA-CN/PMS system exhibits excellent anti-interference performance for various aquatic systems and good durability in continuous-flow experiments, indicating its great potential for water treatment applications. This study provides an in-depth understanding of the distance effect of single-atom active sites on water remediation by designing densely populated SACs.

Basic property and oxygen defect-enhanced nitrogen-doped layered hydroxide-derived oxides MAlO (M = Ni, Co) for carbonyl sulfide hydrolysis at low temperature

Catalytic hydrolysis has been considered the most efficient method for the removal of carbonyl sulfide (COS). However, high-efficiency catalyst was urgently desired. In the present work, nitrogen-doped layered hydroxide-derived oxides (Ni(Co)Al-N) were successfully prepared. It was revealed that N enriched basic sites and oxygen vacancies were well developed for the prepared catalyst. And the catalytic activity was improved significantly. Among the catalysts, the NiAl-N catalyst exhibited the best catalytic activity (can reach 780 min COS 100 % conversion) and lowest activation energy. The concept of OH generation potential was firstly proposed to evaluate the contribution of basic sites to the improvement of catalytic activity. The OH generation potential was greatly improved due to N doping. More importantly, the enhanced basic property and oxygen defect content jointly contributed to the enhancement of catalytic activity. Besides, COS cannot adsorb on the catalyst surface and the reaction obeyed an E-R mechanism. Namely, H2O first adsorbed on basic sites to form OH groups, then COS reacted directly with the formed OH groups, and to generate H2S and CO2 products. HCO3– and HSCO2− were the main intermediate species, and the rate-determining step was the reaction between OCOSH* and H* to form CO2 and H2S.

Dimension dependent photocatalysis over Znln2S4: Controllable synthesis and catalytic mechanism insight

Dimensional control of nano-photocatalysts enables the enhancement of catalytic activity through optimization of electronic structures. In this study, we take Znln2S4 as an example to demonstrate the influence of dimensional structure on photocatalytic reactions. Firstly, we successfully prepared three different dimensional structures of Znln2S4 (including 1D, 2D, and 3D Znln2S4) using a surfactant-assisted synthesis method. In photocatalytic experiments, we found that Znln2S4 exhibits dimension-dependent catalytic performance in both photocatalytic hydrogen production and photodegradation of dye solutions. Among them, 2D ZnIn2S4 demonstrates highest photocatalytic performance. The hydrogen evolution rate of 2D ZnIn2S4 reached 0.69 mmol g−1 h−1, which was 3.29 and 1.17 times higher than 1D ZnIn2S4 and 3D ZnIn2S4, respectively. In addition, the degradation rate of Rodamine B (RhB) by 2D ZnIn2S4 reached 92.3 % within 30 min, significantly higher than that of 1D ZnIn2S4 (70.3 %) and 3D ZnIn2S4 (86.3 %). The origin for high activity of 2D ZnIn2S4 was investigated by multiple perspectives including light absorption range, charge separation efficiency, band structure, and specific surface area. The results revealed that the high activity of 2D ZnIn2S4 may mainly originate from its dimension-controlled high charge separation efficiency.

Single‐nanoparticle electrochemical collision for study of the size‐dependent activity of Au nanoparticles during hydrogen evolution reaction

AbstractIdentifying the intrinsic electrocatalytic activity of an individual nanoparticle is essential to reveal the structure‐activity relations of catalysts. However, it is challenging as the performance of catalysts is typically evaluated with ensembles, providing an elusive averaged response of complex catalyst‐modified electrodes. Herein, a single‐nanoparticle electrochemical collision (SNEC)‐based method was employed to characterize the electrocatalysis of citrate‐capped Au NPs with six different particle sizes, and investigate the size‐dependent electrocatalytic activity of Au NPs toward hydrogen evolution reaction (HER) at the single‐particle level. Results showed that the geometric activity of Au NPs showed a decreasing trend as the size increased from 5 nm to 40 nm, consisting with the linear sweep voltammetry (LSV) data that the onset potentials and potentials to reaching at HER currents of 50 μA cm−2 shifted negatively as the size of Au NPs increased. Also noteworthy is that the measured geometric activity of single Au NP toward HER was 5~6 orders of magnitude higher than the ensemble data derived from the LSV tests. The extraordinary enhancement of catalytic activity is believed to originate from the high accessible surface area of monodispersed Au NPs. Hence, the proposed SNEC‐based method could investigate the intrinsic electrocatalytic activity of NPs in solution at the single‐particle level, and achieve true size‐activity correlation, which may provide effective guidance for the rational design of advanced electrocatalysts.

Metallic Copper-Based Dual-Enzyme Biomimetic Nanoplatform for Mild Photothermal Enhancement of Anticancer Catalytic Activity.

Background: Chemodynamic therapy (CDT) is recognized as a promising cancer treatment. Recently, copper sulfide nanostructures have been extensively employed as Fenton-like reagents that catalyze the formation of acutely toxic hydroxyl radicals (·OH) from hydrogen peroxide (H2O2). However, CDT therapeutic potency is restricted by the tumor microenvironment (TME), such as insufficient amounts of hydrogen peroxide, excessive glutathione levels, etc. To address these disadvantages, glucose oxidase (GOx) or catalase (CAT) can be utilized to enhance CDT, while low therapeutic efficacy still inhibits their future applications. Our previous study revealed that mild photothermal effect could boost the CDT catalytic effectiveness as well as GOx enzyme activity over a range. Results: We engineered and constructed a hollow CuS nanoplatform loaded with GOx and CAT, coating with macrophage membranes (M@GOx-CAT@CuS NPs). The nanoplatforms allowed enhancement of the reactive oxygen species creation rate and GOx catalytic activeness of CDT through mild phototherapy directed by photoacoustic imaging. After actively targeting vascular cell adhesion molecule-1 (VCAM-1) in cancer cells mediated by macrophage membrane coating, M@GOx-CAT@CuS NPs released GOx and CAT under near-infrared irradiation. GOx catalyzed the formation of H2O2 and gluconic acid with glucose, creating a better catalytic environment for CDT. Meanwhile, CAT-catalyzed H2O2 decomposition to generate sufficient oxygen, appropriately alleviating the oxygen shortage in the TME. In addition, starvation effects decreased adenosine triphosphate levels and further underregulated heat shock protein expression to reduce the heat resistance of tumor cells, resulting in a better mild phototherapy outcome. Both invitro and invivo experiments demonstrated that the newly developed M@GOx-CAT@CuS nanoplatform has remarkable synergistic anticancer therapeutic effects. Conclusion: The cascade reaction-enhanced biomimetic nanoplatform opens up a new avenue for precision tumor diagnostic and therapeutic research.

Enhancement of single-atom catalytic activity by interlayer charge transfer in electride-based heterostructures

Single-atom activity will be enhanced by interlayer charge transfer in electride-based heterostructures.

Catalytic hydrolysis of carbonyl sulfide in blast furnace gas over Sm-Ce-Ox@ZrO2 catalyst.

Carbonyl sulfur (COS) is a prominent organic sulfur pollutant commonly found in the by-product gas generated by the steel industry. A series of Sm-doped CeOx@ZrO2 catalysts were prepared for the hydrolysis catalytic removal of COS. The results showed that the addition of Sm resulted in the most significant enhancement of hydrolysis catalytic activity. The 3% Sm2O3-Ce-Ox@ZrO2 catalyst exhibited the highest activity, achieving a hydrolysis catalytic efficiency of 100% and H2S selectivity of 100% within the temperature range of 90-180 °C. The inclusion of Sm had the effect of reducing the acidity of the catalyst while increasing weak basic sites, which facilitated the adsorption and activation of COS molecules at low temperatures. Appropriate doping of Sm proved beneficial in converting active surface chemisorbed oxygen into lattice oxygen, thereby decreasing the oxidation of intermediate products and maintaining the stability of the hydrolysis reaction.

Cobalt-based hybrid nanoparticles loaded with curcumin for ligand-enhanced synergistic nanocatalytic therapy/chemotherapy combined with calcium overload.

The therapeutic efficacy of Fenton or Fenton-like nanocatalysts is usually restricted by the inappropriate pH value and limited concentration of hydrogen peroxide (H2O2) at the tumor site. Herein, calcium carbonate (CaCO3)-mineralized cobalt silicate hydroxide hollow nanocatalysts (CSO@CaCO3, CC) were synthesized and loaded with curcumin (CCC). This hybrid system can simultaneously realize nanocatalytic therapy, chemotherapy and calcium overload. With the stabilization of liposomes, CCC is able to reach the tumor site smoothly. The CaCO3 shell first degrades in an acidic tumor environment, releasing Cur and Ca2+, and the pH value of the tumor is increased simultaneously. Then the exposed CSO catalyzes the Fenton-like reaction to convert H2O2 into ˙OH and enhances the cytotoxicity of curcumin (Cur) by catalytically oxidizing it to a ˙Cur radical. Curcumin not only induces the chemotherapy effect but also serves as a nucleophilic ligand and an electron donor in the catalytic system, enhancing the Fenton-like activity of CCC by electron transfer. In addition, calcium overload also amplifies the efficacy of ROS-based therapy. In vitro and in vivo results show that CCC exhibited an excellent synergistic tumor inhibition effect without any clear side effect. This work proposes a novel concept of nanocatalytic therapy/chemotherapy synergistic mechanism by the ligand-induced enhancement of Fenton-like catalytic activity, and inspires the construction of combined therapeutic nanoplatforms and multifunctional nanocarriers for drug and ion delivery in the future.

Atomic/molecular layer deposition strategies for enhanced CO2 capture, utilisation and storage materials.

Elevated levels of carbon dioxide (CO2) in the atmosphere and the diminishing reserves of fossil fuels have raised profound concerns regarding the resulting consequences of global climate change and the future supply of energy. Hence, the reduction and transformation of CO2 not only mitigates environmental pollution but also generates value-added chemicals, providing a dual remedy to address both energy and environmental challenges. Despite notable advancements, the low conversion efficiency of CO2 remains a major obstacle, largely attributed to its inert chemical nature. It is imperative to engineer catalysts/materials that exhibit high conversion efficiency, selectivity, and stability for CO2 transformation. With unparalleled precision at the atomic level, atomic layer deposition (ALD) and molecular layer deposition (MLD) methods utilize various strategies, including ultrathin modification, overcoating, interlayer coating, area-selective deposition, template-assisted deposition, and sacrificial-layer-assisted deposition, to synthesize numerous novel metal-based materials with diverse structures. These materials, functioning as active materials, passive materials or modifiers, have contributed to the enhancement of catalytic activity, selectivity, and stability, effectively addressing the challenges linked to CO2 transformation. Herein, this review focuses on ALD and MLD's role in fabricating materials for electro-, photo-, photoelectro-, and thermal catalytic CO2 reduction, CO2 capture and separation, and electrochemical CO2 sensing. Significant emphasis is dedicated to the ALD and MLD designed materials, their crucial role in enhancing performance, and exploring the relationship between their structures and catalytic activities for CO2 transformation. Finally, this comprehensive review presents the summary, challenges and prospects for ALD and MLD-designed materials for CO2 transformation.

The metal-support interactions induced catalytic activity enhancement of Pt/TiO2 for hydrogen production from formic acid

The synthesis of noble metal/TiO2 composites without the use of additional reducing agents or surfactants is a notable achievement in catalyst preparation, as it simplifies the process and reduces potential...

Unlocking the chemical environment of nitrogen in perovskite-type oxides.

Nitrogen (N) doping of perovskite-type oxides is an effective method for enhancing their photocatalytic performance. Quantitative and qualitative analyses of the doped N species are essential for a deeper understanding of the catalytic activity enhancement mechanism. However, examining the N environment in perovskite-type oxides, particularly in the bulk, using conventional analytical techniques, such as X-ray photoelectron spectroscopy (XPS), is challenging. In this study, we propose a new analytical technique, advanced temperature-programmed desorption (TPD) up to 1600 °C, to complement the conventional methods. TPD can quantify all N species in bulk oxides. Moreover, it facilitates chemical speciation of N environments, such as substitutional and interstitial N species. This is verified by XPS, CHN elemental analysis, X-ray absorption spectroscopy, and in situ diffuse reflectance infrared Fourier-transform spectroscopy. This study demonstrates the feasibility of advanced TPD as a new analytical method that offers comprehensive information on the N species within N-doped oxide materials at the bulk level.

Selective catalytic reduction of NOX with CH4 over In/SSZ-13 zeolites: The enhancement of high-temperature catalytic activity by Ce modification

The selective catalytic reduction of nitrogen oxides by methane (CH4/NOX-SCR) is a potential technique for the abatement of the NOX emissions from lean-burn GDI engines, due to the excellent thermal stability of CH4. This work focuses on the promotion of In/SSZ-13 catalysts by Ce modification for the CH4/NOX-SCR performance at high temperatures. A series of In/SSZ-13 and Ce-In/SSZ-13 catalysts were prepared using the wetness impregnation method. The effects of Ce modification on the catalytic performance were analysed in detail using the scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet-visible diffuse reflectance spectrum and temperature-programmed desorption/reduction techniques. The results show that the Ce modification significantly enhances the high-temperature activity of the In/SSZ-13 catalysts for the NOX-SCR reaction, especially for the 5 wt% Ce-15 wt% In/SSZ-13 sample which has more than 75% NOX conversion at 390–700 °C. In addition, the Ce modification enhances the water vapor tolerance of the catalyst sample. The Ce modification increases not only the concentration of surface chemisorption oxygen species, but also the relative amount of InO+ species which serve as the main active sites for CH4 activation. Furthermore, the incorporation of Ce into In/SSZ-13 greatly promotes NOX adsorption on the catalyst surface. Most importantly, the Ce modification makes In species well-dispersed on the catalyst surface and thus suppresses the formation of bulk In2O3 species which are more active for the CH4 non-selective oxidation. The combination of all these effects results in the Ce-In/SSZ-13 samples with the superior catalytic activity.

Highly selective formation of isobutene over Zn modified m-ZrO2 catalyst from syngas

The direct synthesis of isobutene from syngas is a very promising route, but there has been a bottleneck in achieving high isobutene selectivity. Here, the efficient synthesis of isobutene from syngas was achieved over a series of Zn modified m-ZrO2 catalysts. Zn species played a key role in improving the physicochemical properties of the m-ZrO2 catalyst. The structure and physicochemical properties of the catalysts were revealed by multiple characterization technique. The characterization results revealed that the introduction of Zn species significantly improved the intensity of Zr3+ and the number of oxygen vacancies. Meanwhile, it also improved the acid-base properties of the m-ZrO2 catalyst. These excellent properties were beneficial to the formation of isobutene from syngas. In CO hydrogenation, 2 % Zn/m-ZrO2 catalyst achieved 93.3 % selectivity for isobutene in C4 hydrocarbons. This enhancement of isobutene selectivity and catalytic activity is very helpful for the development of novel efficient catalysts for the direct synthesis isobutene from syngas.

Activating Co sites activity in Co(OH)2via VN coupling to facilitate highly efficient oxygen evolution reaction

The quest for efficient electrocatalysts to drive the oxygen evolution reaction (OER) is paramount for renewable energy technologies such as water electrolysis. This study focuses on augmenting the catalytic activity of cobalt hydroxide (Co(OH)2) electrocatalysts by strategically coupling them with vanadium nitride (VN) heterostructures (Co(OH)2/VN@C). The synergistic effect between Co(OH)2 and VN is explored to achieve a remarkable improvement in the OER performance that the hybrid Co(OH)2/VN@C exhibits a low overpotential of 319 mV at a current density of 10 mA cm−2 and a small Tafel slope of 65 mV dec−1. Through characterization techniques and electrochemical measurements, we unveil the intricate interplay at the atomic level that triggers the activation of Co sites by V element, leading to an exceptional enhancement in catalytic activity and excellent stability. This work not only sheds light on the fundamental mechanisms involved in the Co(OH)2/VN heterostructure interaction but also presents a promising strategy for designing highly efficient OER electrocatalysts.

Au Nanorods Activated the Zn/Ce Composites with Cancer Cell Specific Cytotoxicity for Enhanced Chemodynamic Therapy.

Chemodynamic therapy based on the Fenton reaction has been developed as an extremely promising modality for cancer therapeutics. In this study, a core-shell structure nanoplatform was constructed by a Au nanorod externally encapsulating Ce/Zn-based composites (ACZO). The nanoparticles can catalyze the generation of reactive oxygen species (ROS) under acidic conditions and effectively consume existing glutathione (GSH) to destroy the redox balance within the tumor. Moreover, the decomposition of the nanocomplexes under acidic conditions releases large amounts of zinc ions, leading to zinc overload in cancer cells. The photothermal effect generated by the Au nanorods not only provides photothermal therapy (PTT) but also augments the catalytic reaction and ions action mentioned above. This facile strategy to improve the efficacy of chemodynamic therapy by the photothermal enhancement of catalytic activity and zinc ion release provides a promising perspective for potential tumor treatment.

The interplay between surface area and sulfur doping of carbon support on Pt NPs nucleation and growth: A synergistic enhancement of catalytic activity for oxygen reduction

Metal–carbon interaction plays a fundamental role in tuning the electrocatalytic behavior of metal nanoparticles (NP). The aim of this study is to emphasize the effective synergy between sulfur doping and the porous structure of the carbon support on the Pt NPs morphology and dimension. Thiophenic-like defects exert a metal-support interaction that affects Pt NPs nucleation and growth and their catalytic activity versus the oxygen reduction reaction (ORR), which makes them promising candidates for the cathode side of PEMFC. Pt NPs defectivity, size, and size dispersion were asserted by using synchrotron wide-angle X-ray total scattering and advanced data analysis. The analyses confirm a mutual correlation between the carbon surface area and the density of sulfur groups with the Pt-specific surface area and with their electrocatalytic properties. The catalytic activity for ORR reaches its peak when a balance is struck between the mesoporosity and the sulfur functionalization of the carbon support.

Enhancement of catalytic activity over Cu-supported montmorillonite catalyst for hydrogen production via steam reforming of dimethyl ether

Enhancement of catalytic activity over Cu-supported montmorillonite catalyst for hydrogen production via steam reforming of dimethyl ether

The role of oxide supports in constructing plasma-treated gold nanocatalysts for visible light photocatalytic oxidation of CO

Supported Au nanocatalysts are highly attractive plasmonic nanostructures for visible light (VL) photocatalysis due to their significant promise in direct conversion of solar to chemical energy. A promising strategy to prepare high-performance supported plasmonic Au nanocatalysts is treating the catalysts with plasma, where the support holds the key to constructing active Au-support interfaces by interacting with Au nanoparticles. Herein the role of oxide supports in constructing plasma-treated plasmonic Au nanocatalysts for VL photocatalytic oxidation of CO is studied by comparing effect of plasma treatment on typical oxides of TiO2, CeO2 and Al2O3 supported Au nanocatalysts. After O2 plasma treatment, CeO2 supported Au nanocatalyst obtains the highest intrinsic catalytic activity due to its high dispersion of Au nanoparticles induced by strong interaction between CeO2 and Au and strong oxygen activation ability. The O2 plasma treatment enables TiO2 supported Au nanocatalyst to exhibit the largest enhancement in catalytic activity under VL irradiation, which originates from the favorable hot-electron transfer process. This process is not only attributed to the strong surface plasmon resonance of Au nanoparticles and large numbers of Au-TiO2 interfacial sites that result from moderate interaction between TiO2 and Au, but also depends on the low Schottky barrier height at Au-TiO2 interface due to the small work function difference between TiO2 and metallic Au. This investigation deepens the understanding of the role of oxide supports in constructing plasma-treated supported Au nanocatalysts, and can be instructive for the design and optimization of plasmonic Au nanocatalysts for VL photocatalytic reactions.

The Origin of Strain Effects on Sulfur Redox Electrocatalyst for Lithium Sulfur Batteries

AbstractIntroducing strain is considered an effective strategy to enhance the catalytic activity of host material in lithium‐sulfur batteries (LSB). However, the introduction of strain through chemical methods often inevitably leads to changes in chemical composition and phase structure, making it difficult to truly reveal the essence and root cause of catalytic activity enhancement. In this paper, strain into MoS2 is introduced through a simple heat treatment and quenching. Experimental research and theoretical analysis show that the strain raises parts of antibonding orbitals in Mo─S bonds above the Fermi level and weakens Li─S and S─S bonds, resulting in tight anchoring and accelerating the conversion for lithium polysulfides (LiPSs). The cells based on the MoS2 with high strain delivers an initial discharge specific capacity as high as 1265 mAh g−1 under 0.2 C and a low average capacity fading of 0.041% per cycle during 1500 cycles under 1 C. This research work deeply reveals the origin of strain effects in the reaction process of LSB, providing important design principles and references for the rational design of high‐performance catalytic materials in the future.

Abstract C083: HDAC6 inhibition increases proteasome activity and modulates the myeloma immunopeptidome to promote cytotoxic T-cell activity

Abstract The proteasome functions as an essential component of immune surveillance by generating peptides from intracellular antigens that are then presented to cytotoxic T-cells. The vast majority of defined antitumor T-cell responses involves the proteasomal processing of intracellular proteins and their presentation in the context of major histocompatibility complex (MHC) class I molecules to antigenic peptide-specific CD8+ T-cells. Such antigenic peptides generated by the proteasome are generally 8-10 amino acids in length and mirror the linear sequence of the parental protein. However, immune evasion is a hallmark of cancer cells that disrupt the antigen processing and presentation machinery. Tumors develop strategies to evade host immunity and resist current immunotherapies, while others display a low tumor mutation burden limiting the presence of tumor antigenicity. Here, we postulated that pharmacologic enhancement of proteasome catalytic activity would increase MHC class I antigen presentation, modulate the myeloma immunopeptidome, and promote CD8+ T-cells anti-myeloma activity. A cell-based, high-throughput screen revealed that the histone deacetylase 6 (HDAC6) inhibitors tubastatin-A, ACY-738 and ACY-1215 increased proteasome activity in multiple myeloma (MM) cells. HDAC6 inhibitors increased pan-MHC class-I expression in MM cells as well as a panel of cancer cell lines. Treatment of MM patient tumor cells with HDAC6 inhibitors increased the cytotoxic effect of autologous patient-derived T-cells. Mechanism-based studies demonstrated that pharmacologic blockade or genetic ablation of the HDAC6 ubiquitin-binding (BUZ) domain disrupted HDAC6 association with HR23B, a substrate-shuttle factor that delivers ubiquitinylated cargo to proteasomes. HDAC6 inhibitors or HDAC6-BUZ domain deletion reduced the association of HR23B with HDAC6 and promoted binding of HR23B to proteasomes and a consequent increase in proteasome activity. The results validate the HDAC6-BUZ domain as an attractive drug discovery target and demonstrate that proteasome activators enhance antitumor immunity. Proteasome activators represent a paradigm-shifting approach to overcome mechanisms of immune escape in cancer cells. FDA-approved drugs that increase proteasome activity and boost antigen presentation and can be repositioned as cancer immunotherapeutics to overcome the existing bottlenecks in drug development. Taken together, our results highlight the breadth and magnitude of the proteasome in governing fundamental cellular processes and the immense potential of therapeutics that exploit proteasomes to treat human disease. Citation Format: Priyanka S. Rana, James J. Ignatz-Hoover, James J. Driscoll. HDAC6 inhibition increases proteasome activity and modulates the myeloma immunopeptidome to promote cytotoxic T-cell activity [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C083.