Catalytic Synergy Research Articles

Loading Lewis Acid/Base Pair on Metal Nanocluster for Catalytic Ugi Reaction

AbstractConstructing structurally robust and catalytically active metal nanoclusters for catalyzing multi‐component reactions is an interesting while challenging task. Inspired by Lewis acid and Lewis base catalysis, we realized the combination of both Lewis acid and Lewis base sites on the surface of a stable gold nanocluster Au35Cd2. The catalytic potential of Au35Cd2 in four‐component Ugi reaction was explored, demonstrating high activity and exceptional recyclability. In‐depth mechanism studies indicate that the catalytic synergy of the Lewis acid/base pair is crucial for the high efficiency of Au35Cd2‐catalyzed Ugi reaction. Bearing the stable structure, multiple activation sites and hierarchical chirality, Au35Cd2 is expected to display further interesting catalytic performance such as asymmetric catalysis.

Methanol steam reforming over copper supported on apatites

Low-temperature methanol steam (MSR) reforming over Cu is an efficient process for releasing H2 from this promising liquid hydrogen carrier but the Cu contents of commercial catalysts are often exceedingly high. Here we show that Sr-exchanged fluoro and hydroxyapatites with 1wt.% Cu exhibit very high methanol turnover frequencies up to 386h-1 and H2 production rates up to 6569mol H2 kgCu-1 h-1 with CO selectivity as low as ~0.25% at 250 °C. Formaldehyde and methyl formate are the only other byproducts which are especially observed over catalysts with low Sr/P ratio in the hydroxyapatite. The reforming proceeds through methoxy, formaldehyde and formate species according to in situ FTIR and mass spectrometric measurements. The spectroscopic analyses further reveal the involvement of apatitic HPO42- ions in the catalytic sequence. Thus, the catalytic synergy between Cu and apatites provides a basis for highly efficient, bifunctional MSR catalysts with low copper content.

Catalytic Synergy between Lewis Acidic Alumina and Pt in Hydrodechlorination for Plastic Chemical Recycling.

Pyrolysis-based plastic chemical recycling has gained significant industrial attention due to its advantage of eliminating complex plastic sorting processes. However, plastic pyrolysis oil contains various components that require stringent removal before subsequent processes. In particular, Cl compounds originating from the decomposition of poly(vinyl chloride) can cause serious corrosion of reactors and catalyst deactivation in downstream processes. While extensive research has been conducted on the removal of other heteroatoms (S, N, and O) from organic compounds via hydrotreating, studies on the removal of Cl have been scarce. In this study, hydrodechlorination over Pt catalysts on various supports is comprehensively investigated using 1,2-dichloroethane as a model reactant. Our results demonstrate that Pt on γ-Al2O3 can exhibit exceptionally high catalytic activity compared to those on other supports due to a distinct bifunctional mechanism. Rigorous studies reveal that the Lewis acidic pentacoordinated Al sites of γ-Al2O3 activate C-Cl bonds, whereas Pt activates H2 and provides spillover H to remove Cl as HCl. The bifunctional mechanism enables the minimized use of precious Pt (<0.1 wt %) to achieve high activity. Pt/γ-Al2O3 also allows for efficient Cl removal (96.8%) with high stability in treating waste plastic pyrolysis oil containing 7500 ppm of Cl.

Synergistic Ni-Ce-SSZ-13 catalysts for enhanced dry reforming of methane

The dry reforming of methane (DRM) serves as a pivotal reaction for hydrogen generation and the simultaneous conversion of methane and carbon dioxide, two major greenhouse gases, into syngas that can further be converted into high-value fuels and chemicals. However, catalyst deactivation imposes a major challenge that prohibits the market penetration of DRM. Here we reported a series of bifunctional Ni-Ce catalysts supported on SSZ-13 (Ni-Ce-SSZ-13) and discovered that a small amount of Ce could significantly enhance the activity, selectivity, and stability for DRM. Optimal ratio of Ni to Ce has been identified to yield peak catalytic performance. The optimal performance is correlated with the maximum Ce3+/Ce4+ ratio as revealed by XPS analysis, which implies an increased presence of oxygen vacancies in the catalysts. It played a crucial role in facilitating the oxidation of activated CH4 species at Ni sites, thereby enhancing DRM activity and diminishing the detrimental coke formation. It is also disclosed that integrating proper amount of Ce fosters its interactions with Ni, effectively preventing the agglomeration of Ni sites. This work presents great implications for the rational design and catalytic synergy of bi-/multi-functional zeolite catalysts for other technological applications.

Mn-MOF derived N-doped MnOx@carbon heterogeneous catalysts for Vis-light, S2O82[sbnd], HSO5[sbnd], Vis/S2O82[sbnd], and Vis/HSO5[sbnd]-induced degradation of metronidazole: Kinetics and mechanistic study

Manganese oxide-based nanostructures have demonstrated remarkable potential for reactive radical generation to treat wastewater by activating persulfate (PS) and peroxymonosulfate (PMS) in the presence of visible-light irradiation. Herein, we report a facile strategy to synthesize nitrogen-doped porous MnOx@Carbon nanostructures by annealing Mn-based MOF at different temperatures and employed for the degradation of MTZ under Vis-light, PS, PMS, Vis/PS, and Vis/PMS systems. A significant catalytic synergy was found in the MnO-I/Vis/PMS system. Owing to the rational coordination of nitrogen-enriched porous manganese oxide embedded carbon, high surface area (179.6 m2/g), and surface-exposed abundant active sites, the composite named MnO-I exhibited excellent catalytic performance in all the studied processes. The carbonization process induces a polarization difference between Mn-N co-ordination, resulting in the carbon becoming an electron-deficient core and manganese an electron-rich center, thus providing more Mn (II/III) for PMS activation. The degradation study showed that 99 % removal of MTZ was achieved within 40 min, with a rate constant of 0.099 min−1, in the MnO-I/Vis/PMS system. Trapping experiments and EPR detection demonstrated that SO4•−, OH• and 1O2 radicals were the major species involved in the degradation process. Besides, the degradation pathway and impact of operational parameters, i.e., catalyst dosage, PMS concentration, initial pH, MTZ concentration, co-existing anions, and humic acid, on the removal of MTZ were also explored.

Catalytic synergy: N,P modification of activated carbon for improved 1-chloro-4-nitrobenzene reduction

Carbon materials have emerged as a new generation of catalysts for the crucial industrial hydrogenation of nitroarenes. Activated carbon, known for its cost-effectiveness and facile modifiability, stands out among various carbon materials. This study focuses on the preparation of N and P co-doped carbons for catalysing the hydrogenation of 1-chloro-4-nitrobenzene. Comprehensive characterisation using thermal analysis (TGA-MS), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, N2 adsorption at −196 °C, and ICP-MS was performed. The synergistic effect of N and P was evident, with co-doped carbons outperforming their mono-doped counterparts, underscoring the significance of nitrogen. N,P-codoped activated carbon emerges as a promising, active, stable, and selective metal-free catalyst for the hydrogenation of 1-chloro-4-nitrobenzene, leading to 4-chloroaniline.

Cyclodextrin-boosted photocatalytic oxidation for efficient bisphenol A removal

Wastewater contains various high-risk trace organic pollutants, such as antibiotics and endocrine disruptors, which seriously restrict wastewater reuse. Cyclodextrin-based functional materials show great potential in the removal of trace pollutants because of their adsorption catalytic synergy. Clarifying the synergistic mechanism of cyclodextrin in oxidation is the key issue in confined catalytic oxidation process design. In this work, we fabricated a BiOIO3@BiOBr/β-CD heterojunction photocatalyst to study the synergistic mechanism of cyclodextrin in the photocatalytic oxidation process. The synergistic mechanism of cyclodextrin was investigated by combining radical chemistry, electrochemistry, spectroscopy, and time-dependent density functional theory. Results showed that the excited intermediate free radicals played an important role in promoting the photocatalytic degradation process. The heterojunction photocatalyst loaded with β-cyclodextrin (β-CD) at the electronic end (C[Cat.] = 0.2 mg/mL) removed about 97% of bisphenol A (BPA) within 30 min, and the first-order kinetic constant (kCDBIB = 0.112 min−1) was about twice that of the unloaded β-CD (kBIB = 0.057 min−1). Cyclodextrin loading improved the photocatalytic performance of the heterojunction and stimulated the intermediate to increase the free radical yield and regulate the reaction path.

Identification of hyperthermophilic D-allulose 3-epimerase from Thermotoga sp. and its application as a high-performance biocatalyst for D-allulose synthesis.

D-Allulose 3-epimerase (DAE) is a vital biocatalyst for the industrial synthesis of D-allulose, an ultra-low calorie rare sugar. However, limited thermostability of DAEs hinders their use at high-temperature production. In this research, hyperthermophilic TI-DAE (Tm = 98.4 ± 0.7 ℃) from Thermotoga sp. was identified via in silico screening. A comparative study of the structure and function of site-directed saturation mutagenesis mutants pinpointed the residue I100 as pivotal in maintaining the high-temperature activity and thermostability of TI-DAE. Employing TI-DAE as a biocatalyst, D-allulose was produced from D-fructose with a conversion rate of 32.5%. Moreover, TI-DAE demonstrated excellent catalytic synergy with glucose isomerase CAGI, enabling the one-step conversion of D-glucose to D-allulose with a conversion rate of 21.6%. This study offers a promising resource for the enzyme engineering of DAEs and a high-performance biocatalyst for industrial D-allulose production.

Boosting selective hydrogenation of α,β-unsaturated aldehydes through constructing independent Pt and Fe active sites on support

The alloy catalysts usually exhibited excellent catalytic synergy owing to the electronic and ensemble effect. However, the process of alloying makes the displacement of the d-band center from the Fermi level, decreasing the adsorption strength of reactant molecules. Herein, we constructed the spatial separation catalyst in which the independent Pt and FeOx nanoparticles were uniformly distributed on SBA-15 support (denoted as Pt = Fe/SBA-15), which exhibits remarkable efficiency in the hydrogenation of α,β-unsaturated aldehydes, i.e. with a 4 fold higher than the corresponding alloy catalyst in reaction rate, and a 4 fold increase in selectivity for cinnamalcohol production compared to the single Pt catalyst. It is found that Pt primarily catalyzes the H2 dissociative adsorption into H*, while FeOx mainly catalyzes the reaction between H* and aldehydes, forming alcohols. Assuming that the rate-determining-step is the H-spillover from Pt to Fe, the two cascade reactions are interconnected. To confirm this mechanism, we employ a physical mixture catalyst of Pt/SBA-15 and FeOx/SBA-15, where its catalytic activity lies between Pt = Fe/SBA-15 and alloy materials. The catalysts’ structures are well characterized by STEM and EDS mapping analysis, and the mechanism is supported by experimental data and DFT calculations. The research we conducted offers a new perspective into the cooperative catalysis, achieved by coupling independent active centers in thermos-hydrogenation reactions.

In-situ sodium chloride template synthesis of γ-WO3 hollow cubes for high-sensing and dual-selective hydrazine/dibutylamine detection at different temperatures

The fabrication of a chemiresistive sensor with dual-selectivity to highly toxic and explosive N2H4/dibutylamine (DBA) remains challenging due to no report. To this aim, we synthesized uniform (NH4)0.33WO3 cuboid precursors through optimized solvothermal reaction and in-situ formed NaCl template. Subsequently, the precursors were calcined in air to transform into γ-WO3 hollow cubes (WO3-HC) assembled from near-spherical nanoparticles, and the effect of calcination temperature on microstructures and gas-sensing properties was investigated. Among, WO3-HC-5 obtained by calcining precursor at 500 °C has broad pore channels, large specific surface area and abundant oxygen vacancy defects. Under the catalytic synergy of surface W6+ Lewis acid with dangling bonds, WO3-HC-5 sensor realizes the bifunctional monitoring of N2H4 and DBA. It presents large response value (S = 606.6) to 100 ppm N2H4 at 50 °C and a good response (S = 76.7) to the same concentration of DBA at 217 °C, and has fast response rate, low practical detection limit, satisfactory stability and humidity resistance. WO3-HC-5 represents the first metal oxide-based sensor with dual-selectivity towards aforementioned harmful gases at different operating temperatures. Moreover, the bifunctional mechanism has been characterized and analyzed in detail.

A {P6Mo18}-type heteropolyblue modified NiO-based carbon nanofibers for bifunctional biosensors

Non-enzymatic electrochemical biosensors have great application value in the identification and detection of organic biological small molecules, especially in biomedical detection. In this paper, a carbon-based sensing material consisting of basket-type polyoxometallates (POMs) modified with synergistic multicomponent active centers was prepared. A novel POMs with heteropolyblue properties, {Co(phen)3}3[{Co(H2O)2}{Co(H2O)3}4}{Sr ⊂ P6MoVI16MoV2O73}2]·8H2O (CoP6Mo18), was modified on NiO-loaded carbon nanofibers (NiO-CNFs) to construct novel nanocomposites CoP6Mo18@NiO-CNFs. Differential pulse voltammetry (DPV) tests show that the nanocomposite electrode had a strong response to L-tryptophan (L-Trp) and dopamine (DA) with lower detection limit of 22.2 nM and 27.8 nM (S/N = 3) in the linear range of 66.7 nM-478 μM and 83.3 nM-437 μM, respectively. The results demonstrated that the modified electrode can quickly and efficiently detect DA and L-Trp alone or together due to catalytic synergy between CoP6Mo18 and NiO-CNFs. The combination of the two materials not only enhances the current response signals of the electrodes to the analytes DA and L-Trp, but also effectively improves the selectivity and stability of the sensor. Importantly, the prepared sensor can be used for trace detection of DA and L-Trp in pre-treated human serum samples in practical applications, and the recovery rate is as high as 98.9 %, which suggests that the CoP6Mo18@NiO-CNFs/GCE sensor has potential application value in biology and medical fields.

Porous carbon/Fe3O4 nanocomposite as a new magnetically recoverable catalyst for the preparation of polyhydroquinolines.

A porous carbon/Fe3O4 nanocomposite (PC/Fe3O4 nanocomposite) was prepared through the pyrolysis of peanut shells as biowaste with ferrous ferric oxide to give a new magnetically recoverable catalyst. In the designed nanocomposite, magnetic iron oxide nanoparticles are properly distributed on the surface and cavities of porous carbon obtained from biomass. Increasing the active surface and magnetic recovery capability results in catalytic synergy, thereby promoting the reaction with an appropriate catalytic effect. The catalytic ability of the porous carbon/Fe3O4 nanocomposite as a nanomagnetically recoverable catalyst was successfully tested for the synthesis of polyhydroquinolines.

Catalytic synergy of WS2-anchored PdSe2 for highly sensitive hydrogen gas sensor.

Hydrogen (H2) is widely used in industrial processes and is one of the well-known choices for storage of renewable energy. H2 detection has become crucial for safety in manufacturing, storage, and transportation due to its strong explosivity. To overcome the issue of explosion, there is a need for highly selective and sensitive H2 sensors that can function at low temperatures. In this research, we have adequately fabricated an unreported van der Waals (vdWs) PdSe2/WS2 heterostructure, which exhibits exceptional properties as a H2 sensor. The formation of these heterostructure devices involves the direct selenization process using chemical vapor deposition (CVD) of Pd films that have been deposited on the substrate of SiO2/Si by DC sputtering, followed by drop casting of WS2 nanoparticles prepared by a hydrothermal method onto device substrates including pre-patterned electrodes. The confirmation of the heterostructure has been done through the utilization of powder X-ray diffraction (XRD), depth-dependent X-ray photoelectron spectroscopy (XPS) and field-emission scanning electron microscopy (FE-SEM) techniques. Also, the average roughness of thin films is decided by Atomic Force Microscopy (AFM). The comprehensive research shows that the PdSe2/WS2 heterostructure-based sensor produces a response that is equivalent to 67.4% towards 50 ppm H2 at 100 °C. The response could be a result of the heterostructure effect and the superior selectivity for H2 gas in contrast to other gases, including NO2, CH4, CO and CO2, suggesting tremendous potential for H2 detection. Significantly, the sensor exhibits fast response and a recovery time of 31.5 s and 136.6 s, respectively. Moreover, the explanation of the improvement in gas sensitivity was suggested by exploiting the energy band positioning of the PdSe2/WS2 heterostructure, along with a detailed study of variations in the surface potential. This study has the potential to provide a road map for the advancement of gas sensors utilizing two-dimensional (2D) vdWs heterostructures, which exhibit superior performance at low temperatures.

Enhanced Hot Electron Flow and Catalytic Synergy by Engineering Core-Shell Structures on Au-Pd Nanocatalysts.

The synergistic catalytic performances of bimetallic catalysts are often attributed to the reaction mechanism associated with the alloying process of the catalytic metals. Chemically induced hot electron flux is strongly correlated with catalytic activity, and the interference between two metals at the atomic level can have a huge impact on the hot electron generation on the bimetallic catalysts. In this study, we investigate the correlation between catalytic synergy and hot electron chemistry driven by the electron coupling effect using a model system of Au-Pd bimetallic nanoparticles. We show that the bimetallic nanocatalysts exhibit enhanced catalytic activity under the hydrogen oxidation reaction compared with that of monometallic Pd nanocatalysts. Analysis of the hot electron flux generated in each system revealed the formation of Au/PdOx interfaces, resulting in high reactivity on the bimetallic catalyst. In further experiments with engineering the Au@Pd core-shell structures, we reveal that the hot electron flux, when the topmost surface Pd atoms were less affected by inner Au, due to the concrete shell, was smaller than the alloyed one. The alloyed bimetallic catalyst forming the metal-oxide interfaces has a more direct effect on the hot electron chemistry, as well as on the catalytic reactivity. The great significance of this study is in the confirmation that the change in the hot electron formation rate with the metal-oxide interfaces can be observed by shell engineering of nanocatalysts.

Enhanced activity of plasma catalysis for propane decomposition via metal-support interactions of Pt/CeMnyOx

The elimination of light alkanes has been the subject of extensive research. Rational tuning of the surface electronic structure of catalysts can optimize the adsorption and activation behavior of reactant molecules. Therefore, the role of metal-support interactions in plasma catalysis deserves in-depth investigation. In this study, a simple strategy was employed to synthesize Pt-based catalysts loaded on Ce-based binary oxide supports. The interactions between Pt noble metal and supports were regulated by varying the metal element type of the supports and the ratio of the support metal elements. Among them, 0.3 %Pt/CeMn0.2Ox catalyst was the most effective for the synergistic plasma degradation of propane. Various characterizations showed that the redox ability and Pt species dispersion of 0.3 %Pt/CeMn0.2Ox catalyst were significantly enhanced by strong metal-support interactions. It induced more Pt0 and Ce3+ on the surface for the activation of oxygen or water vapor to generate surface reactive oxygen species. Moreover, the plasma in turn facilitated the electron transfer of Pt/CeMn0.2Ox catalyst and enhanced the metal-support interactions. The reactive oxygen species generated by plasma participated in the oxidation of propane and the oxygen cycle of Pt/CeMn0.2Ox catalyst, thus enhancing the synergistic catalysis. The present work provides insight into the design of catalysts with high plasma catalytic synergy.

Understanding catalytic synergy in dinuclear polymerization catalysts for sustainable polymers

Understanding the chemistry underpinning intermetallic synergy and the discovery of generally applicable structure-performances relationships are major challenges in catalysis. Additionally, high-performance catalysts using earth-abundant, non-toxic and inexpensive elements must be prioritised. Here, a series of heterodinuclear catalysts of the form Co(III)M(I/II), where M(I/II) = Na(I), K(I), Ca(II), Sr(II), Ba(II) are evaluated for three different polymerizations, by assessment of rate constants, turn over frequencies, polymer selectivity and control. This allows for comparisons of performances both within and between catalysts containing Group I and II metals for CO2/propene oxide ring-opening copolymerization (ROCOP), propene oxide/phthalic anhydride ROCOP and lactide ring-opening polymerization (ROP). The data reveal new structure-performance correlations that apply across all the different polymerizations: catalysts featuring s-block metals of lower Lewis acidity show higher rates and selectivity. The epoxide/heterocumulene ROCOPs both show exponential activity increases (vs. Lewis acidity, measured by the pKa of [M(OH2)m]n+), whilst the lactide ROP activity and CO2/epoxide selectivity show linear increases. Such clear structure-activity/selectivity correlations are very unusual, yet are fully rationalised by the polymerization mechanisms and the chemistry of the catalytic intermediates. The general applicability across three different polymerizations is significant for future exploitation of catalytic synergy and provides a framework to improve other catalysts.

Critical role of support crystal structures on highly selective hydrodeoxygenation of lignin-derived vanillin over Pd/ZrO2 catalysts

Hydrodeoxygenation (HDO) of bio-oils obtained by rapid pyrolysis of biomass into high value-added chemicals generally required harsh conditions. Herein, three kinds of mixed-phase ZrO2 supports (denoted as ZSX, X = 2–4) with different crystal structure proportions were prepared by one-pot hydrothermal synthesis method, and their performance on the properties of Pd/ZrO2 catalysts were investigated for vanillin HDO. Pd/ZS3 exhibited excellent efficiency in HDO of vanillin, a typical model compound of lignin, achieving approximately 100% yield of 2-methoxy-4-methylphenol (MMP) in presence of n-butanol as solvent and polymethyl hydrogen siloxane (PMHS) as hydrogen donor under mild conditions (35 °C, 1 h). It was due to catalytic synergy of exposed metal active sites, oxygen vacancies (Ov) and acid sites to occur electron transfer and enhance interaction between Pd and ZrO2. By tuning the crystal structure of ZrO2 support, the influence of Ov and acid sites of Pd/ZrO2 over vanillin HDO performance was investigated, Pd/ZS2 with abundant Ov and Pd/ZS4 with substantial acid sites promoted hydrogenation and hydrogenolysis, respectively, Pd/ZS3 possessed preferable conversion and selectivity as having the properties of both at once. Additionally, reaction pathway was also proposed in which vanillin was converted to MMP by combining intermediate of 4-hydroxy-methyl-2-methoxyphenol (HMP) with active hydrogen species while removing water. This developed catalysts with different crystalline highlighted an enormous promise for HDO of bio-oils into green fuel under mild conditions.

Rational Design of Highly Efficient PdIn–In2O3 Interfaces by a Capture-Alloying Strategy for Benzyl Alcohol Partial Oxidation

Well-dispersed PdIn bimetallic alloy nanoparticles (1-4 nm) were immobilized on mesostructured silica by an in situ capture-alloying strategy, and PdIn-In2O3 interfaces were rationally constructed by changing the In2O3 loading and reduction temperature. The catalytic performance for benzyl alcohol partial oxidation was evaluated, and a catalytic synergy was observed. The Pd-rich PdIn-In2O3 interface is prone to be formed on the catalyst with a low In2O3 loading after being reduced at 300 °C. It was demonstrated that the Pd-rich PdIn-In2O3 interface was more active for benzyl alcohol partial oxidation than In-rich Pd2In3 species, which was likely to be formed at a high reduction temperature (400 °C). The high catalytic activity on the Pd-rich PdIn-In2O3 interface was attributed to the exposure of more Pd-enriched active sites, and an optimized PdIn-In2O3/Pd assemble ratio enhanced the oxygen transfer during partial oxidation. The density functional theory (DFT) calculation confirmed that the Pd-rich Pd3In1(111)-In2O3 interface facilitated the activation of oxygen molecules, resulting in high catalytic activity.

Boosted Oxygen Reduction Reaction Activity by Ordering Cations in the A-Site of a Perovskite Catalyst

As concerns related to climate change continue to grow, there has been an increasing number of studies on materials that can enhance the efficiency of energy conversion/storage systems. Since the oxygen reduction reaction (ORR) is considered as a rate-determining reaction for the O2 conversion system, it is essential to develop an efficient electrocatalyst that enables greater ORR activity. Perovskite has been explored as a promising electrocatalyst due to its excellent ORR activity at high and room temperatures. Recently, unique perovskite structures that can contain high oxygen vacancy ratios, such as brownmillerite, Ruddlesden–Popper, and layered perovskite, have been studied for exhibiting high ORR performance. However, few studies have dealt with the electrochemical properties of perovskite, which has different structures but the same cation stoichiometry, to know the exact effect of a specific structure. In this study, we synthesized two materials with different structures (cubic structure perovskite and layered structure perovskite) but with the same cation stoichiometry. The layered structure rather than the cubic structure showed cation ordering in the A-site of the perovskite structure with an enhanced oxygen vacancy ratio. As a result, the layered structure exhibits superior electrochemical performance than the cubic structure at high and room temperatures by a factor of ca. 2.7 at 500 °C in fuel cell mode, and ca. 5.5% decrease in overpotential (η) at −3 mA cm–2 for ORR catalysis. Moreover, perovskite hybridized with nitrogen doped reduced graphene oxide (N-rGO) could compensate for the intrinsic shortcoming of perovskite oxide and exert a catalytic synergy (27% decrease in η).

Switchable Enzyme-mimicking catalysts Self-Assembled from de novo designed peptides and DNA G-quadruplex/hemin complex.

Reconstruction of enzymatic active site in an artificial system is key to achieving high catalytic efficiency. Herein, we report the self-assembly of the lysine-containing peptides with guanine-rich DNA and hemin to form peroxidase-mimicking active sites and catalytic nanoparticles. The DNA strand self-folds into a G-quadruplex structure that provides a supramolecular scaffold and a potential axial ligand for hemin. The β-sheet forming capability of the lysine-containing peptides is found to affect the catalytic synergy between the G-quadruplex DNA and the peptide. It is hypothesized that the β-sheet formation of the peptides results in the enrichment of the lysine residues, which distribute on the distal side of hemin to promote the formation of Compound I, like distal arginine residue in natural heme pocket. Incorporation of the histidine residues into the lysine-containing peptides further enhanced the hemin activities, indicating the cooperation between the lysine and histidine. Furthermore, the peptide/DNA/hemin complexes can be switched between active and inactive state by reversible formation and deformation of the DNA G-quadruplex, which was attributed to the peptides-promoted conformational changes of the DNA components. This work opens an avenue to mimic the catalytic residues and their spatial distribution in the natural enzymes, and shed light on the design of the smart biocatalysts that can respond to the environmental stimuli.