Tandem Catalysis Research Articles

Tandem Electrocatalytic Reduction of Nitrite to Ammonia on Rhodium–Copper Single Atom Alloys

AbstractElectrocatalytic reduction of NO2− to NH3 (NO2RR) presents a fascinating approach for simultaneously migrating NO2− pollutants and producing valuable NH3. In this study, single‐atom Rh‐alloyed copper (CuRh1) is explored as a highly active and selective catalyst toward the NO2RR. Combined theoretical calculations and in situ FTIR/EPR spectroscopic experiments uncover the synergistic effect of Rh1 and Cu to promote the NO2RR energetics of CuRh1 through a tandem catalysis pathway, in which Rh1 activates the preliminary adsorption and hydrogenation of NO2− (NO2− → *NO2 → *NOOH → *NO), while the generated *NO on Rh1 is then transferred on Cu substrate which promotes the rate‐determining step of *NO → *NHO toward the NH3 synthesis. As a result, CuRh1 equipped in a flow cell presents an unprecedented NH3 yield rate of 2191.6 µmol h−1 cm−2 and NH3‐Faradaic efficiency of 98.9% at a high current density of 322.5 mA cm−2, as well as long‐term stability for 100 h electrolysis.

Tandem catalysis of furfural to γ-valerolactone over polyoxometalate-based metal-organic frameworks: Exploring the role of confinement in the catalytic process

Polyoxometalate-based metal-organic frameworks (POMOFs) with bifunctional Lewis-Brønsted acid were designed by confining polyoxometalates (POMs: phosphotungstic acid (PW), phosphomolybdic acid (PMo) or silicotungstic acid (SiW)) within the Zr-MOFs. The confined POMs not only have their own Brønsted acid, but can also regulate the Lewis acid strength of the POMOFs via charge regulation, ultimately allowing the POMOFs to display superior catalytic performance in the tandem catalysis of furfural (FAL) to γ-valerolactone (GVL). Among the three catalysts (POMOF-PW, POMOF-PMo and POMOF-SiW), a complete conversion of FAL was achieved, while POMOF-PW exhibited the highest GVL yield (58.1 %) at 160 °C within 23 h. The leaching experiment and structural characterization of the catalyst before and after recycling confirmed the stability of the catalyst structure. The humin originates from the polymerization of furan ring-containing compounds driven by Brønsted acid. The adsorption configuration of the substrate molecules on the catalyst offers a new explanation for the tandem reaction process, i.e. that perpendicular adsorption performs only the first step of the tandem reaction, while the coexistence of perpendicular and horizontal adsorption permits the entire reaction process. This work gives unique insights into the tandem reaction of FAL and can guide the design of efficient tandem reaction catalysts.

Effective synthesis of circRNA via a thermostable T7 RNA polymerase variant as the catalyst.

Circular RNAs (circRNAs) are endogenous noncoding RNAs (ncRNAs) with transcriptional lengths ranging from hundreds to thousands. circRNAs have attracted attention owing to their stable structure and ability to treat complicated diseases. Our objective was to create a one-step reaction for circRNA synthesis using wild-type T7 RNA polymerase as the catalyst. However, T7 RNA polymerase is thermally unstable, and we streamlined circRNA synthesis via consensus and folding free energy calculations for hotspot selection. Because of the thermal instability, the permuted intron and exon (PIE) method for circRNA synthesis is conducted via tandem catalysis with a transcription reaction at a low temperature and linear RNA precursor cyclization at a high temperature. To streamline the process, a multisite mutant T7 RNA polymerase (S430P, N433T, S633P, F849I, F880Y, and G788A) with significantly improved thermostability was constructed, and G788A was used. The resulting mutant exhibited stable activity at 45°C for over an hour, enabling the implementation of a one-pot transcription and cyclization reaction. The simplified circRNA production process demonstrated an efficiency comparable to that of the conventional two-step reaction, with a cyclization rate exceeding 95% and reduced production of immunostimulatory dsRNA byproducts.

Light-induced phase transformation to two-dimensional amorphous spinel CoAlOx nanosheets as a tandem photothermal catalyst for efficient and durable toluene oxidation

Low temperature fabrication of spinel oxides and development of efficient and durable toluene photothermal catalysts remain challenging. Herein, two-dimensional amorphous spinel CoAlOx nanosheets (CoAl-LDH-L2) have been fabricated via a light-induced phase transformation strategy using intense photooxidation. Light-induced decomposition and phase transformation process have been used to elucidate the growth mechanism. The CoAl-LDH-L2 exhibits improved toluene adsorption and photothermal conversion, with the highest photothermal catalytic toluene conversion (∼100 % at 500 ppm) at 90 °C, outperforming most previously reported catalysts. Irradiation with mild external heating significantly increases the mineralization rate (∼90 %) and improves the long-term and cycling stability (∼5% losses within 39 h) relative to that under single-light-driven conditions. In-situ DRIFT spectroscopy was also performed for revealing the “tandem photothermal catalysis” mechanism for toluene conversion. This work offers a novel strategy for developing spinel oxides as low-temperature photothermal catalyst in a green and sustainable way.

A Proline-Based Artificial Enzyme That Favors Aldol Condensation Enables Facile Synthesis of Aliphatic Ketones via Tandem Catalysis.

A proline-based artificial enzyme is prepared by grafting the l-proline moieties onto the surface of bovine serum albumin (BSA) protein through atom transfer radical polymerization (ATRP). The artificial enzyme, the BSA-PolyProline conjugate, prefers to catalyze the formation of unsaturated ketones rather than β-hydroxy ketones in the reaction between acetone and aldehydes, which is difficult to achieve in free-proline catalysis. The altered reaction selectivity is ascribed to the locally concentrated l-proline moieties surrounding the BSA molecule, indicating a microenvironmental effect-induced switching of the reaction mechanism. Taking advantage of this selectivity, we used this artificial enzyme in conjunction with a natural enzyme, old yellow enzyme 1 (OYE1), to demonstrate a simple synthesis of different aliphatic ketones from acetone and aldehydes via tandem catalysis.

Upgrading CO2 to sustainable aromatics via perovskite-mediated tandem catalysis

The directional transformation of carbon dioxide (CO2) with renewable hydrogen into specific carbon-heavy products (C6+) of high value presents a sustainable route for net-zero chemical manufacture. However, it is still challenging to simultaneously achieve high activity and selectivity due to the unbalanced CO2 hydrogenation and C–C coupling rates on complementary active sites in a bifunctional catalyst, thus causing unexpected secondary reaction. Here we report LaFeO3 perovskite-mediated directional tandem conversion of CO2 towards heavy aromatics with high CO2 conversion (> 60%), exceptional aromatics selectivity among hydrocarbons (> 85%), and no obvious deactivation for 1000 hours. This is enabled by disentangling the CO2 hydrogenation domain from the C-C coupling domain in the tandem system for Iron-based catalyst. Unlike other active Fe oxides showing wide hydrocarbon product distribution due to carbide formation, LaFeO3 by design is endowed with superior resistance to carburization, therefore inhibiting uncontrolled C–C coupling on oxide and isolating aromatics formation in the zeolite. In-situ spectroscopic evidence and theoretical calculations reveal an oxygenate-rich surface chemistry of LaFeO3, that easily escape from the oxide surface for further precise C–C coupling inside zeolites, thus steering CO2-HCOOH/H2CO-Aromatics reaction pathway to enable a high yield of aromatics.

Bidirectional tandem catalysis coupled with interface engineering and Se vacancies for accelerating the polysulfide conversion

The shuttling of long-chain LiPSs (Li2Sn, 4 ≤ n ≤ 8) and the sluggish conversion from Li2S4 to Li2S represent two primary challenges hindering the fast multi-step transformations of lithium-sulfur (Li-S) batteries. Here, we propose a bidirectional tandem catalytic strategy to promote polysulfide conversions. A novel nanostructured catalyst consisting of hollow bimetallic selenide (ZnSe/SnSe2) cubes with dual-active centers, heterogeneous interfaces and selenium-rich vacancies was synthesized. Experimental and theoretical calculations confirmed that ZnSe and SnSe2 selectively reduced the thermodynamic transition energy barrier of S8→Li2S4 and Li2S4→Li2S to achieve baton-relay-like conversion of polysulfides. Moreover, the synergistic effect of ZnSe and SnSe2 significantly reduced the activation barrier of Li2S reoxidation during the charging process, and achieved an efficient bidirectional catalytic conversion. In situ Raman analysis confirmed that ZnSe/SnSe2 effectively inhibited the shuttle effect. As a result, a battery with ZnSe/SnSe2 interlayer delivered high specific capacity of 1269.5 mAh g−1 at 0.2 C, and excellent rate capability (680.4 mAh g−1 at 4 C). Remarkably, the battery maintained cycling stability with only 0.086% capacity degradation per cycle after 500 cycles at 2 C. This work provides a new path for designing electrocatalyst towards precise control of catalytic processes in Li-S batteries.

Transition Metal Ru(II) Catalysts Immobilized Nanoreactors for Conditional Bioorthogonal Catalysis in Cells.

Employing transition metal catalysts (TMCs) to perform bioorthogonal activation of prodrugs and pro-fluorophores in biological systems, particularly in a conditional fashion, remains a challenge. Here, we used a mesoporous organosilica nanoscaffold (RuMSN), which localizes Ru(II) conjugates on the pore wall, enabling the biorthogonal photoreduction reactions of azide groups. Due to easily adjustable surface charges and pore diameter, this efficiently engineering RuMSN catalyst, with abundant active sites on the inner pore well, could spontaneously repel or attract substrates with different molecular sizes and charges and thus ensure selective bioorthogonal catalysis. Depending on it, engineering RuMSN nanoreactors showed fascinating application scales from conditional bioorthogonal activation of prodrugs and pro-fluorophores in either intra- or extracellular localization to performing intracellular concurrent and tandem catalysis together with natural enzymes.

The synergistic tandem effect of Cu2+1O and Co3O4 enhances the activity and selectivity of nitrate reduction to ammonia in neutral solution

Construction the electrocatalysts with multiple components is an effective strategy to enhance the activity for NH3 generation in electrocatalytic nitrate reduction reaction (NITRR). Herein, we report a high performance electrocatalyst Co3O4-Cu2+1O/CF. The obtained Co3O4-Cu2+1O/CF nanosheets not only provide large active surface area but also construct the bimetal oxides interface for exerting Cu-Co tandem catalysis. Meanwhile, Co3O4-Cu2+1O/CF exhibits a maximum NH3-Faradaic efficiency of 96.5% and NH3 yield of 0.26 mmol h−1 cm−2 in neutral solution with 10 mM NO3-. The control experiments and Tafel analysis clearly manifest the tandem catalysis mechanism on Co3O4-Cu2+1O/CF, where Cu2+1O favors the NO3- conversion to NO2-, while Co3O4 selectively promotes NO2- conversion to NH3. The DFT calculations reveal that the strengthened NO3- adsorption and the enhanced adsorption of H* on Co3O4-Cu2+1O/CF jointly promote the selective formation of ammonia from NO3- reduction. This work provides the strategy of constructing the efficient transition metal composited electrocatalysts in NITRR.

Selective Hydrocracking of Waste Polyolefins toward Gasoline-Range Liquid Fuels via Tandem Catalysis over a Cerium-Promoted Pt/HY Catalyst

Selective Hydrocracking of Waste Polyolefins toward Gasoline-Range Liquid Fuels via Tandem Catalysis over a Cerium-Promoted Pt/HY Catalyst

Spatial compartmentalisation effects for multifunctionality catalysis: From dual sites to cascade reactions

Catalysis plays a key role in the production of fuels, industrial chemicals and the chemical transformation of fine chemicals. As society faces increasing environmental pollution and energy crises, tandem catalysis has attracted increasing attention as an outstanding model due to its sustainability and environmental friendliness. Compared with traditional stepwise synthesis methods, tandem catalysis not only can couple several different reactions together, but also does not require the separation of intermediates, which provides new ideas for improving reaction activity, regulating product selectivity and developing new methods for catalysis. In order to catalyse cascade reactions efficiently, it is crucial to design suitable multifunctional catalysts, which should contain at least two active sites and achieve spatial separation. Here, we introduce the realisation and application of spatial segregation of metal, acidic and basic sites with examples to provide further insight into the indispensable role of active site compartmentalisation effects in tandem catalysis. In addition, this study highlights the challenges and issues associated with such catalysts, emphasising the importance of effective catalyst enhancement and environmentally sustainable catalytic transformations. The results of the study are intended to provide guidance for the development of rational and efficient catalysts.

Hydrogen Production through Distinctive C-C Cleavage during Acetic Acid Reforming at Low Temperature.

Acetic acid reforming is a green method for sustainable hydrogen production owing to its renewable source from biomass conversion. However, conventional acetic acid reforming would produce various byproducts, including CO, CH4 and so on. Here, we develop a distinctive method for selective hydrogen production from C-C directional cleavage during acetic acid reforming. Completely different from conventional acetic acid reforming process, acetic acid would react with water over organoruthenium catalyst during its C-C cleavage at low temperature, then produce methanol and formic acid (CH3COOH+H2O→CH3OH+HCOOH). Lastly, methanol and formic acid could further decompose into hydrogen and carbon dioxide over organoruthenium selectively. As a result, there is little CO and CH4 produced in the first step of C-C bond cleavage during acetic acid reforming at 100 °C. Hydrogen production rate is up to 26.8 molH2/(h-1*mol-1 Ru) at 150 °C through a tandem catalysis. A mechanism for C-C cleavage of acetic acid is proposed based on intermediate product analysis and density functional theory (DFT) calculation. Firstly, the C-C single bond was transformed into C=C double bond by dropping one H atom to organoruthenium. Then the coming H2O molecule reacted with the C=C bond by an addition reaction, forming methanol and formic acid. This research not only proposes distinctive reaction pathway for hydrogen production from acetic acid reforming, but also provides some inspiration for selective C-C bond cleavage during ethanol reforming.

Tandem catalysis in electrocatalytic nitrate reduction: Unlocking efficiency and mechanism

AbstractThe electrochemical nitrate reduction reaction (NO3RR) holds promise for ecofriendly nitrate removal. However, the challenge of achieving high selectivity and efficiency in electrocatalyst systems still significantly hampers the mechanism understanding and the large‐scale application. Tandem catalysts, comprising multiple catalytic components working synergistically, offer promising potential for improving the efficiency and selectivity of the NO3RR. This review highlights recent progress in designing tandem catalysts for electrochemical NO3RR, including the noble metal‐related system, transition metal electrocatalysts, and pulsed electrocatalysis strategies. Specifically, the optimization of active sites, interface engineering, synergistic effects between catalyst components, various in situ technologies, and theory simulations are discussed in detail. Challenges and opportunities in the development of tandem catalysts for scaling up electrochemical NO3RR are further discussed, such as stability, durability, and reaction mechanisms. By outlining possible solutions for future tandem catalyst design, this review aims to open avenues for efficient nitrate reduction and comprehensive insights into the mechanisms for energy sustainability and environmental safety.

Tandem catalysis enables chlorine-containing waste as chlorination reagents

Chlorinated compounds are ubiquitous. However, accumulation of chlorine-containing waste has a negative impact on human health and the environment due to the inapplicability of common disposal methods, such as landfill and incineration. Here we report a sustainable approach to valorize chlorine-containing hydrocarbon waste, including solids (chlorinated polymers) and liquids (chlorinated solvents), based on copper and palladium catalysts with a NaNO3 promoter. In the process, waste is oxidized to release the chlorine in the presence of N-directing arenes to afford valuable aryl chlorides, such as the FDA-approved drug vismodegib. The remaining hydrocarbon component is mineralized to afford CO, CO2 and H2O. Moreover, the CO and CO2 generated could be further utilized directly. Thus, chlorine-containing hydrocarbon waste, including mixed waste, can serve as chlorination reagents that neither generate hazardous by-products nor involve specialty chlorination reagents. This tandem catalytic approach represents a promising method for the viable management of a wide and diverse range of chlorine-containing hydrocarbon wastes.

Ultrasound-activated piezo-hot carriers trigger tandem catalysis coordinating cuproptosis-like bacterial death against implant infections

Implant-associated infections due to the formation of bacterial biofilms pose a serious threat in medical healthcare, which needs effective therapeutic methods. Here, we propose a multifunctional nanoreactor by spatiotemporal ultrasound-driven tandem catalysis to amplify the efficacy of sonodynamic and chemodynamic therapy. By combining piezoelectric barium titanate with polydopamine and copper, the ultrasound-activated piezo-hot carriers transfer easily to copper by polydopamine. It boosts reactive oxygen species production by piezoelectrics, and facilitates the interconversion between Cu2+ and Cu+ to promote hydroxyl radical generation via Cu+ -catalyzed chemodynamic reactions. Finally, the elevated reactive oxygen species cause bacterial membrane structure loosening and DNA damage. Transcriptomics and metabolomics analysis reveal that intracellular copper overload restricts the tricarboxylic acid cycle, promoting bacterial cuproptosis-like death. Therefore, the polyetherketoneketone scaffold engineered with the designed nanoreactor shows excellent antibacterial performance with ultrasound stimulation and promotes angiogenesis and osteogenesis on-demand in vivo.

The tandem catalysis of porous CoW composite oxide: Intensified allylic oxidation of cyclohexene to 2-cyclohexene-1-one

The controllable oxidation of the allylic CH bond has great academic and industrial value. Different Co/W ratios of CoW composite oxides were prepared using hydrothermal method and used in the allylic oxidation reaction of cyclohexene containing unstable allylic hydrogen atoms and carbon-carbon double bonds. The relationship between the structure of active sites and catalytic performance was revealed using characterization techniques such as XRD, N2 adsorption/desorption, SEM, TEM, FT-IR, UV–vis, and XPS. The results indicated that the Co(II)/Co(III) sites effectively mediate the first step of the entire oxidation reaction system, which generates hydroxyl radicals and peroxyl radicals through the activation of H2O2 to achieve chain initiation. Subsequently, the cyclohexene underwent a series of chain migration reactions under the action of hydroxyl radicals and peroxyl radicals, resulting in the formation of 2-cyclohexen-1-one and 2-cyclohexen-1-ol. Finally, 2-cyclohexen-1-ol interacted with W(VI) sites to form 2-cyclohexen-1-one via an alcohol-coordinated hydroxyl intermediate. The tandem oxidation reaction of cyclohexene allylic oxidation and 2-cyclohexen-1-ol dehydrogenation was realized by the CoW synergistic catalytic. The synergy between Co and W sites, composed of Co-O-W units on the surface of the CoW oxide with porous channel features, was elucidated. The experimental results showed that under the optimal conditions, using CoW composite oxide (Co/W = 1:1) as the catalyst, a 79.8% conversion rate of cyclohexene was achieved with 93.9% selectivity for the allylic products, among which the selectivity for 2-cyclohexen-1-one was 73.8%.

Direct synthesis of iso-olefins from carbon dioxide hydrogenation via tandem catalysis

Direct synthesis of iso-olefins from carbon dioxide hydrogenation via tandem catalysis

Last Decades’ Overview on Tandem Catalysis: Intrigue in Organo-metallic Chemistry

Abstract: Catalytic transformations have been observed in every reaction to provide a specific product and to formulate regio and stereo-selective adducts in well-defined pathways. Among various catalytic processes used in current chemistry, tandem catalysis has been proven to be an effective technology by applying the technology for better and time-saving ways of production. It has shown its usability in various fields of research like organic reactions, inorganic salt extractions, isolation, and purification of intermediates, photoprotection of dye, pigment, and polymer chemistry, specifically in paint industries, biological sequencing and natural product chemistry. Ideally, it is a single molecule conversation to the desired product (beneficial to both research and industries) with many competing effects in spatial arrangement with almost no major equipment in operation. The advantages of tandem catalysis in the field of chemistry (Organic/Biochemistry/ Polymer chemistry etc.) by utilizing the positive side is a newer way for energetic and favourable technology.

Unlocking Birch Lignin Hydrocracking through Tandem Catalysis: Unraveling the Role of Moderate Hydrogen Spillover

Unlocking Birch Lignin Hydrocracking through Tandem Catalysis: Unraveling the Role of Moderate Hydrogen Spillover

Cobalt phthalocyanine promoted copper catalysts toward enhanced electro reduction of CO2 to C2: Synergistic catalysis or tandem catalysis?

The activity and selectivity of electrocatalytic CO2 reduction reaction (CO2RR) to C2 products on metal catalysts can be regulated by molecular surfactants. However, the mechanism behind it remains elusive and debatable. Herein, copper nanowires (Cu NWs) were fabricated and decorated with cobalt phthalocyanine (CoPc). The electronic interaction between the Cu NWs, CoPc, CO2 and CO2RR intermediates were explored by density functional theory (DFT) calculations. It was found that the selectivity and activity of CO2RR towards C2 products on Cu NWs were considerably enhanced from 35.2% to 69.9% by surface decoration of CoPc. DFT calculations revealed that CO2RR can proceed in the interphase between Cu substrate and CoPc, and the CO2RR intermediates could synergistically bond with both Cu and Co metal centre in CuNWs-CoPc, which favours the adsorption of CO2, CO and CO2RR intermediates, thus reducing the free energy for CO-CO coupling towards C2 products. The synergistic interaction was further extended to phthalocyanine (Pc) and other metal phthalocyanine derivatives (MPc), where a relatively weaker synergistic interaction of CO intermediates with MPc and Cu substrate and only a slight enhancement of CO2RR towards C2 products were observed. This study demonstrates a synergistic catalysis pathway for CO2RR, a novel perspective in interpreting the role of CoPc in enhancing the activity and selectivity of CO2RR on Cu NWs, in contrast to the conventional tandem catalysis mechanism.