Bifunctional Catalysts Research Articles

Synthesis of anion M-doped NiCoP (M = S, Se and N) as bifunctional catalysts for alkaline seawater and urea splitting

Synthesis of anion M-doped NiCoP (M = S, Se and N) as bifunctional catalysts for alkaline seawater and urea splitting

NiFeS2/NiFe2O4 composites constructed by etching modified Fe foam as an efficient bifunctional catalysts for overall water splitting

NiFeS2/NiFe2O4 composites constructed by etching modified Fe foam as an efficient bifunctional catalysts for overall water splitting

Efficient Bifunctional Electrocatalysts for Oxygen Evolution/Reduction Reactions in Two-Dimensional Metal-Organic Frameworks by a Constant Potential Method.

The evolution of bifunctional catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts that are highly active, stable, and conductive is crucial for advancing metal-air batteries and fuel cells. We have here thoroughly explored the OER and ORR performance for a category of two-dimensional (2D) metal-organic frameworks (MOFs) called TM3(HADQ)2, and Rh3(HADQ)2 exhibits a promising bifunctional OER/ORR activity, with an overpotential of 0.31 V for both OER and ORR. The d-band center (εd) and crystal orbital Hamilton populations (COHP) are utilized to study the relationship between OER/ORR activity and the electronic structure of catalysts, and it is found that the elementary d-electron number (Ne) of the central TM for TM3(HADQ)2, as well as the electronegativity of the ligand TM-N4 and the intermediate O atom, are the main reason that affects the catalytic activity of OER/ORR. Additionally, Rh3(HADQ)2 can be proven through the constant potential method (CPM) and microkinetics method that it is an acidic OER/ORR bifunctional catalyst. Rh3(HADQ)2 has a high toxicity tolerance, making it a potential bifunctional catalyst. Our research contributes to both the rational design of SACs for various catalytic processes and the fabrication of bifunctional, cost-effective oxygen-electric catalysts.

Chromite–Zeolite Catalysts for Syngas Conversion to Hydrocarbons: Insights into Oxide–Zeolite Interactions

AbstractA key challenge in modern society is developing the sustainable processes for producing vital chemicals, such as hydrocarbons, from renewable raw materials. The OX‐ZEO process, which uses bifunctional catalysts to convert syngas into hydrocarbons, offers a potential alternative to the nonsustainable cracking process. Combining oxide materials with zeolites enables the direct synthesis of various hydrocarbon products with high selectivity. However, challenges remain, particularly regarding carbon monoxide (CO) conversion and unwanted carbon dioxide (CO2) generation. This study explores the impact of bimetallic chromites combined with H‐MOR zeolite on the reaction outcome. Comparative experiments using only the oxide versus the bifunctional catalyst revealed a clear link between the methanol synthesis activity of the oxide and the overall activity in the OX‐ZEO process. Furthermore, catalytic tests with monometallic oxides paired with H‐MOR highlighted the role of the oxide's crystal structure in syngas conversion. These findings offer insights into the oxide–zeolite interactions, enabling the development of improved catalyst combinations that enhance the CO conversion, reduce CO2 formation, and maintain high product selectivity.

Development of Bifunctional Catalysts for CO2 Capture and Conversion at Low Temperatures Under an Electric Field

AbstractSystems for direct conversion of captured CO2 into CO (i.e., CO2 capture and reduction: CCR) via bifunctional catalysts have attracted attention as technologies for achieving carbon neutrality. However, the reported systems require additional heating above 623 K, which is still an issue from an ecological perspective. The present work realized selective CO production through CCR under isothermal conditions at 423 K by the application of a direct current electric field and a Pt‐Na/TiO2 catalyst. The application of an electric field to the catalyst is needed for CO2 conversion at low temperature, and the loading of both Pt and Na is required for CO2 capture and its selective reduction to CO. The obtained results open the door for greener CCR technologies that effectively utilize waste heat from power plants and industry.

Progress and Perspective of Noble‐Metal‐Free Bifunctional Oxygen Electrocatalysts for Zinc‐Air Batteries

AbstractRechargeable Zn‐air batteries (ZABs) have attracted widespread attention due to their advantages, such as high energy density, low price, and environmental friendliness. However, the sluggish kinetics of ORR/OER greatly prevent the practical application of rechargeable ZABs. In recent years, efficient, durable, and cost‐effective bifunctional catalysts are developed to accelerate the kinetics of ORR/OER and enhance the performance of ZABs. This review provides a systematic overview of ZABs and describes the standards of bifunctional oxygen electrocatalysts. The latest research progress in the development of non‐noble metal‐based and nano‐metallic electrocatalysts for the air electrode of ZABs is systematically summarized, including the classification, design, synthesis methods, active site structures, and mechanism. Finally, the challenges faced by bifunctional catalysts and probable solutions are proposed. This review will provide a comprehensive guidance for development of efficient oxygen electrocatalyst in the future.

Electronic Promoter Breaks the Linear Scaling Relationship: Ultra‐Rapid High‐Temperature Synthesis of Heterostructured CoS/SnO2@C as a Bifunctional Oxygen Catalyst for Li‐O2 Batteries

AbstractLi‐O2 batteries urgently needs high discharge capacity and stable cycling performance, requiring effective and reliable bifunctional catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, Hovenia acerba Lindl‐like heterostructure composed of cobalt sulfide and tin dioxide supported on carbon substrate (CoS/SnO2@C) is prepared via CO2 laser irradiation technology. The half‐wave potential of CoS/SnO2@C for the ORR is 0.88 V, while the overpotential of the OER at 10 mA cm−2 is as low as 270 mV. The Li‐O2 batteries employing the bifunctional CoS/SnO2@C catalyst displays a high discharge specific capacity of 3332.25 mAh g−1 and long cycling life of 226 cycles. Additionally, theory calculations demonstrate that the construction of heterostructure decreases energy barrier of the rate‐determining step (RDS) for both ORR and OER. Notably, SnO2 behaves as the electronic promoter to optimize the electronic structure of heterostructure interface and triggers charge redistribution of CoS, which weakens the adsorption strength of the *O‐intermediates and allows to break the linear scaling relationship, thus further enhancing the catalytic performance of CoS/SnO2@C. This research furnishes directions for the design of heterogeneous catalysts, highlighting its great potential for application in rechargeable Li‐O2 batteries.

Fisher-Tropsch synthesis in the presence of bifunctional catalysts based on hierarchical zeolite MFI

The effect of the hierarchical pore structure of ZSM-5 zeolites obtained by alkali modification on the composition of the synthesized products and the catalytic properties of bifunctional cobalt catalysts for the Fischer-Tropsch synthesis was studied. The bifunctional catalysts were prepared by mechanically mixing the Co-Al2O3/SiO2 catalyst, HZSM-5 zeolite and boehmite binder. The HZSM-5 zeolite was preliminarily subjected to alkali modification with different alkali concentrations (0.1, 0.25, 0.5, and 1.0 M) to create a hierarchical porous structure and change the acidic properties of the zeolite. The samples of ZSM-5 zeolites and the bifunctional catalysts prepared on their basis were characterized by SEM, low-temperature nitrogen adsorption-desorption, X-ray diffraction and H2 TPR. Catalytic tests were carried out in a tubular reactor with a fixed catalyst bed at a pressure of 2.0 MPa, a temperature of 250 °C and a gas space velocity of 1000 h–1. The tests were performed for 70–80 h of continuous operation. The fractional composition of the Fischer-Tropsch synthesis products was studied at a temperature of 250 °C. It was shown that preliminary treatment of zeolite ZSM-5 with a 0.5 M alkali solution contributed to an increase in the yield and productivity of branched hydrocarbons to 62% and 70.3 kg/(m3cat∙h) compared to a similar bifunctional catalyst based on the industrial microporous zeolite HZSM-5.

Electronic Structure Modulation Induced by the Synergy of Cobalt Low-Nuclearity Clusters and Mononuclear Sites for Efficient Oxygen Electrocatalysis.

The development of high-performance bifunctional single-atom catalysts for use in applications, such as zinc-air batteries, is greatly impeded by mild oxygen reduction and evolution reactions (ORR and OER). Herein, we report a bifunctional oxygen electrocatalyst designed to overcome these limitations. The catalyst consists of well-dispersed low-nuclearity Co clusters and adjacent Co single atoms over a nitrogen-doped carbon matrix (CoSA+C/NC). The precisely tailored asymmetric electronic structures are achieved with strong electronic interactions between these Co species. The Co clusters optimize the adsorption/desorption strength of oxygenated intermediates on single-atomic Co sites to endow exceptional activity under alkaline conditions with a half-wave potential (E1/2) of 0.91 V and an overpotential (η) of 340 mV at 10 mA cm-2. In addition, a zinc-air battery assembled with CoSA+C/NC achieves a high power density of 284.1 mW cm-2 and a long operational lifespan of 400 h, superior to those of the benchmark Pt/C + RuO2. Experimental findings and theoretical analysis reveal that the enhanced bifunctional activity stems from the synergistic interactions between Co clusters and single-atomic Co sites. Consequently, the overbinding of *OH is suppressed with accelerated *OH removal. This work establishes the design principle of advanced electrocatalysts with multiphase metal species bearing strong electronic interactions.

Grain-Boundary-Rich Pt/Co3O4 Nanosheets for Solar-Driven Overall Water Splitting.

Interfacial engineering is considered an effective strategy to improve the electrochemical water-splitting activity of catalysts by modulating the local electronic structure to expose more active sites. Therefore, we report a platinum-cobaltic oxide nanosheets (Pt/Co3O4 NSs) with plentiful grain boundary as the efficient bifunctional electrocatalyst for water splitting. The Pt/Co3O4 NSs exhibit a low overpotential of 55 and 201 mV at a current density of 10 mA cm-2 for the hydrogen evolution reaction and oxygen evolution reaction in 1.0 M potassium hydroxide, respectively. A negligible degradation of 1.52 V at a current density of 10 mA cm-2 after continuous operation for 100 h, demonstrates the long-term stability of the catalyst. Furthermore, the overall water-splitting performance of the Pt/Co3O4 NSs surpasses that of the commercial Pt/C||RuO2. The density functional theory calculation results explain that the improvement of catalyst activity is attributed to the moderate adsorption/desorption energy of *H and the low reaction energy barrier of the rate-determining step. This work presents a novel vision to design bifunctional catalysts for the storage and conversion of hydrogen energy.

Combined Catalytic Conversion of NOx and VOCs: Present Status and Prospects

This article presents a comprehensive examination of the combined catalytic conversion technology for nitrogen oxides (NOx) and volatile organic compounds (VOCs), which are the primary factors contributing to the formation of photochemical smog, ozone, and PM2.5. These pollutants present a significant threat to air quality and human health. The article examines the reaction mechanism and interaction between photocatalytic technology and NH3-SCR catalytic oxidation technology, highlighting the limitations of the existing techniques, including catalyst deactivation, selectivity issues, regeneration methods, and the environmental impacts of catalysts. Furthermore, the article anticipates prospective avenues for research, underscoring the necessity for the development of bifunctional catalysts capable of concurrently transforming NOx and VOCs across a broad temperature spectrum. The review encompasses a multitude of integrated catalytic techniques, including selective catalytic reduction (SCR), photocatalytic oxidation, low-temperature plasma catalytic technology, and biological purification technology. The article highlights the necessity for further research into catalyst design principles, structure–activity relationships, and performance evaluations in real industrial environments. This research is required to develop more efficient, economical, and environmentally friendly waste gas treatment technologies. The article concludes by outlining the importance of collaborative management strategies for VOC and NOx emissions and the potential of combined catalytic conversion technology in achieving these goals.

Synergistic Pathways in PLA Breakdown and PTMC Formation: A One‐Pot Eutectic‐Driven Recycling Mechanism

This study introduces a novel one‐pot strategy for the chemical valorization of poly(lactic acid) (PLA), coupling its base‐catalyzed depolymerization with the ring‐opening polymerization (ROP) of trimethylene carbonate (TMC). The process exploits an eutectic mixture of lactide (LA) and TMC, which lowers the thermal input required for PLA degradation. Using potassium aryloxide (KOArtBu) as a bifunctional catalyst, the PLA is first quickly hydrolyzed into oligomers or lactic acid, which subsequently initiate the slower polymerization of TMC. Notably, this transformation operates in the presence of residual water, eliminating the need for tedious drying steps. The method achieves selective PLA breakdown conversion and produces (oligo)lactic acid end‐capped poly(trimethylene carbonate) (PTMC) with tunable molar mass, depending on water content.

Synergistic Pathways in PLA Breakdown and PTMC Formation: A One-Pot Eutectic-Driven Recycling Mechanism.

This study introduces a novel one-pot strategy for the chemical valorization of poly(lactic acid) (PLA), coupling its base-catalyzed depolymerization with the ring-opening polymerization (ROP) of trimethylene carbonate (TMC). The process exploits an eutectic mixture of lactide (LA) and TMC, which lowers the thermal input required for PLA degradation. Using potassium aryloxide (KOArtBu) as a bifunctional catalyst, the PLA is first quickly hydrolyzed into oligomers or lactic acid, which subsequently initiate the slower polymerization of TMC. Notably, this transformation operates in the presence of residual water, eliminating the need for tedious drying steps. The method achieves selective PLA breakdown conversion and produces (oligo)lactic acid end-capped poly(trimethylene carbonate) (PTMC) with tunable molar mass, depending on water content.

Sulfur-modified Co3O4 as a bifunctional oxygen catalyst for zinc-air batteries

Sulfur-modified Co3O4 as a bifunctional oxygen catalyst for zinc-air batteries

Solar-Driven Sulfide Oxidation Paired With CO2 Reduction Based on Vacancies Engineering of Copper Selenide.

Photovoltaic-driven electrochemical (PV-EC) carbon dioxide reduction (CO2R) coupled with sulfide oxidation (SOR) can efficiently convert the solar energy into chemical energy, expanding its applications. However, developing low-cost electrocatalysts that exhibit high selectivity and efficiency for both CO2R and SOR remains a challenge. Herein, a bifunctional copper selenide catalyst is developed with copper vacancies (v-CuSe2) for the CO2R-SOR. The Faradaic efficiency (FE) of 62.4% for methane at -200mA cm-2 is achieved in the cathodic CO2R. In a two-electrode CO2R-SOR system with 16 h of long-term operation at a current density of 200mAcm-2, an average Faradaic efficiency of 57.2% for methane and 97.7% for sulfur powder generation is achieved at cathode and anode, respectively. Compared to the coupling of CO2R with oxygen evolution reaction (OER), the energy efficiency (EE) of the CO2R-SOR system can be increased to 22.9%. The mechanism study has found that the synergistic effect of copper vacancies and introduced Se significantly enhances the selectivity toward methane. Driven by silicon solar cells, a solar-to-methane conversion efficiency of 2% is achieved.

Exploring the Catalytic Potential of Bioinspired Taurine‐Functionalized Carbon Quantum Dots as Bifunctional Catalysts for Diverse Sustainable Organic Transformations in Water.

Taurine‐functionalized Carbon Quantum Dots (Tau‐CQDs) were synthesized and evaluated for their catalytic potential under metal‐, acid‐, and base‐free sustainable conditions, using water as a solvent for various organic transformations, including Knoevenagel condensation, the Biginelli reaction, and the Knoevenagel‐Michael cascade. These bioinspired N, S‐doped CQDs exhibit bifunctionality, acting as hydrogen bond donors and acceptors for C–C, C–N, and C–O bond formation. Comprehensive characterization of the catalyst was performed using HRTEM, PXRD, XPS, FTIR, AFM, Zeta potential, UV‐Vis, and photoluminescence spectrometry. The Tau‐CQDs demonstrated excellent reusability, maintaining catalytic performance over 10 cycles. Green chemistry metrics, including a low E‐factor, high atom economy, and favorable PMI, CE, and RME values, highlight this approach's environmental and economic advantages. Key properties, such as high reaction yields, short reaction times, water solubility, enhanced surface functionality, non‐toxicity, and mild operating conditions, underscore the broader significance of Tau‐CQDs as an efficient, sustainable catalytic platform. Additionally, the simple recovery of the catalyst via filtration, without the need for further purification, enhances its practical applicability.

Hydrocracking of n-Hexadecane and Diesel Fuels over Bifunctional Catalysts based on High-Crystallinity Granulated Hierarchical ZSM-5 Zeolites

Hydrocracking of n-Hexadecane and Diesel Fuels over Bifunctional Catalysts based on High-Crystallinity Granulated Hierarchical ZSM-5 Zeolites

Integration of Fe3C and Fe3P Nanoparticles Anchored on N-Doped Carbon as Bifunctional Oxygen Catalysts for Rechargeable Zn-Air Batteries

Integration of Fe₃C and Fe₃P Nanoparticles Anchored on N-Doped Carbon as Bifunctional Oxygen Catalysts for Rechargeable Zn-Air Batteries

Mechanism-Guided Development of Bifunctional Cyclooctenes as Active, Practical, and Light-Gated Bromination Catalysts.

Most molecular catalysts have been developed employing polar functional groups as catalytic sites. However, the use of non-polar functional groups for catalysis has received less attention due to their modest molecular interactions while the bioorthogonal reactivity of non-polar alkenes as substrates is frequently used in click chemistry. In this study, we conducted mechanistic studies on the catalysis of trans-cyclooctene (TCO) derivatives with the strained olefin as the catalytic site using kinetic and computational analyses to aid the design of more active olefin catalysts. The analysis reveals the significant role of the benzyl substituents in accelerating the generation of bromonium species through dispersion interaction in the rate-determining step. Guided by the mechanistic insights, we developed bifunctional TCO catalysts bearing a functionalized benzyl group, taking advantage of the remarkable substituent effects. Experimental studies confirmed the theoretical model and revealed that TCO with a para-hydroxybenzyl group provided excellent catalytic activity. Furthermore, inclusion of the functionalized benzyl groups allowed more readily available and robust cis-cyclooctenes to be used as active catalysts, expanding the practical utility of the olefin catalysts. By using a photochemically labile masking group on the para-hydroxybenzyl substituent, the first light-gated bromination catalyst was developed, enabling spatiotemporal control of the transformation.

Preparation and Characterization of Sulfonated CaO Catalyst for Biodiesel Production from Waste Cooking Oil

Biodiesel production depends on raw materials. Low-quality oils, such as cooking oil, crude palm oil, and sludge oil, are used to reduce costs, and they contain free fatty acids (FFA) and water. Soap can be produced when using the alkaline catalyst during transesterification. In this work, the sulfonation method prepared the esterification of waste cooking oil by sulfonated CaO as a bifunctional catalyst. The sulfonated CaO catalysts were characterized by X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), temperature-programmed desorption of carbon dioxide and ammonia (TPD), BET surface area, and scanning electron microscopy (SEM). It was observed that the specific surface area, pore volume, and pore diameter of the CaO increased after being sulfonated with a 2 M sulfuric acid solution. It showed a high total surface acidity and basicity, 7.22 and 3.86 mmol/g, respectively. The optimal FFA conversion (84.94 %) from the waste cooking oil was acquired at a reaction temperature of 65 ˚C, a 9:1 MeOH: Oil molar ratio, and 5 wt% catalyst loading for a 3 h reaction time. The 2 M sulfonated CaO catalyst can be reused twice with a high FFA conversion without further treatment under optimized reaction conditions. The 2 M sulfonated CaO catalyst has potential treatment for biodiesel production from high-FFA oils due to its lower production cost and high catalytic activity.