Environmental Catalysis Research Articles

Exploring of laccase-like nanozyme and membrane filters for efficient removal of tetracycline hydrochloride

Laccase is utilized as green catalyst in the environmental catalysis. Nevertheless, the drawbacks such as poor stability and difficulty in recycling have seriously restricted its application. Here, we simulated the binding pocket and catalytic active site of nature laccase, and designed a laccase-mimicking nanozyme (named as GA-Cu and the average diameter was 600 nm) with high activity and stability by using Cu2+ as the active center, 2-aminoimidazole as well as glutathione (GSH) as the ligand. Compared with natural laccase, the GA-Cu nanozymes showed excellent stability and reusability under extreme conditions. Furthermore, to overcome the problems of difficult recycling and easy secondary contamination, we innovatively proposed to load GA-Cu nanozymes onto nylon membranes (GA-Cu@CS/GA-Cu/nylon membranes) by vacuum-assisted filtration using chitosan (CS) as a binder to degrade tetracycline hydrochloride (TC) by filtration. Encouragingly, 50 mg/L of TC was almost completely removed by filtration once at 0.15 MPa pressure. The results have showed that the GA-Cu@CS/GA-Cu/nylon membrane removed TC mainly through degradation, and more than 80 % of TC was degraded through desorption experiments. Finally, some degradation products were identified by LC-MS and three possible degradation pathways were proposed. These findings demonstrate the potential of GA-Cu@CS/GA-Cu/nylon membrane for environmental remediation, and will be a general and important strategy for the design of membrane filters based on the excellent performance of nanozyme.

One-Pot Synthesis of (CrMnFeCoNi)Ox High-Entropy Oxides for Efficient Catalytic Oxidation of Propane: A Promising Substitute for Noble Metal Catalysts.

The efficient catalytic oxidation of propane, as a short-chain alkane, remains challenging in environmental catalysis. High-entropy oxides (HEOs) exhibit advantages in abundant and well-dispersed elemental composition, exceptional thermal stability, and enriched lattice defects. Herein, (CrMnFeCoNi)Ox HEO catalysts are successfully synthesized by using a continuous hydrothermal flow synthesis (CHFS) route, without any subsequent calcination processes. This route yields HEOs with fine particle sizes, high specific surface areas, and abundant near-surface lattice oxygen compared to the traditional coprecipitation method. Notably, the propane conversion over the CHFS-made (CrMnFeCoNi)Ox HEO reaches 90% at 255 °C, with an apparent activation energy of 53.2 kJ/mol, mainly attributed to its enriched lattice oxygen and enhanced oxygen mobility that prevent the accumulation of acetates and the consequent occupation of active sites. In comparison to commercial Pt/Al2O3 and Pd/Al2O3, (CrMnFeCoNi)Ox HEO demonstrates exceptional activity and can maintain long-term stability under high-temperature (upon 650 °C) and moisture-rich conditions (at 2-10 vol %). These attributes highlight its potential as a promising substitute for noble metal catalysts in industrial applications.

Improving the Chemical Utilization Efficiency of Pd Hydrodechlorination Catalysts through Hydrogen-Spillover Empowered Synergy between Pd and TiNiN Support.

The sustainable and affordable environmental application of Pd catalysis needs further improvement of Pd mass activity. Besides the well-recognized importance of physical utilization efficiency─the ratio of surface atoms forming reactant-accessible reactive sites─a lesser-known fact is that the congestion of these reactive sites, which we term as the chemical utilization efficiency, also influences the mass activity. Herein, by leveraging the 100% physical utilization efficiency of a fully exposed Pd cluster (Pdn) and the hydrogenation activity of TiNiN, we developed Pdn/TiNiN as a high physical and chemical utilization efficiency catalyst. During the catalytic hydrodechlorination of 4-chlorophenol and the subsequent hydrogenation of phenol, Pdn focuses on H2 dissociation and C-Cl cleavage, while TiNiN facilitates the subsequent hydrogenation of phenol into less toxic cyclohexanone via H-spillover. This synergy results in a 20-40-fold increase in the hydrodechlorination rate. The enhanced chemical utilization efficiency of Pd informs the design of Pdn/TiNiN microspheres for the conversion of halogenated organics from pharmaceutical wastewater and the design of a fixed-bed reactor to transfer trace amounts of 4-CP from river water. Ultimately, this approach decentralizes the use of Pd in environmental catalysis and reduction processes.

Polyoxometalates-Mediated Selectivity in Pt Single-Atoms on Ceria for Environmental Catalysis.

Optimizing the reactivity and selectivity of single-atom catalysts (SACs) remains a crucial yet challenging issue in heterogeneous catalysis. This study demonstrates selective catalysis facilitated by a polyoxometalates-mediated electronic interaction (PMEI) in a Pt single-atom catalyst supported on CeO2 modified with Keggin-type phosphotungstate acid (HPW), labeled as Pt1/CeO2-HPW. The PMEI effect originates from the unique arrangement of isolated Pt atoms and HPW clusters on the CeO2 support. Electrons are transferred from the ceria support to the electrophilic tungsten in HPW clusters, and subsequently, Pt atoms donate electrons to the now electron-deficient ceria. This phenomenon enhances the positive charge of Pt atoms, moderating O2 activation and limiting lattice oxygen mobility compared to the conventional Pt1/CeO2 catalyst. The resulting electronic structure of Pt combined with the strong and local acidic environment of HPW on Pt1/CeO2-HPW leads to improved efficiency and N2 selectivity in the degradation of NH3 and NO, as well as increased CO2 yield when inputting volatile organic compounds. This study sheds the light on the design of SACs with balanced reactivity and selectivity for environmental catalysis.

Polyoxometalates‐Mediated Selectivity in Pt Single‐Atoms on Ceria for Environmental Catalysis

AbstractOptimizing the reactivity and selectivity of single‐atom catalysts (SACs) remains a crucial yet challenging issue in heterogeneous catalysis. This study demonstrates selective catalysis facilitated by a polyoxometalates‐mediated electronic interaction (PMEI) in a Pt single‐atom catalyst supported on CeO2 modified with Keggin‐type phosphotungstate acid (HPW), labeled as Pt1/CeO2‐HPW. The PMEI effect originates from the unique arrangement of isolated Pt atoms and HPW clusters on the CeO2 support. Electrons are transferred from the ceria support to the electrophilic tungsten in HPW clusters, and subsequently, Pt atoms donate electrons to the now electron‐deficient ceria. This phenomenon enhances the positive charge of Pt atoms, moderating O2 activation and limiting lattice oxygen mobility compared to the conventional Pt1/CeO2 catalyst. The resulting electronic structure of Pt combined with the strong and local acidic environment of HPW on Pt1/CeO2‐HPW leads to improved efficiency and N2 selectivity in the degradation of NH3 and NO, as well as increased CO2 yield when inputting volatile organic compounds. This study sheds the light on the design of SACs with balanced reactivity and selectivity for environmental catalysis.

Urea/Thiourea Imine Linkages Provide Accessible Holes in Flexible Covalent Organic Frameworks and Dominates Self‐Adaptivity and Exciton Dissociation

Unraveling the robust self‐adaptivity and minimal energy‐dissipation of soft reticular materials for environmental catalysis presents a compelling yet unexplored avenue. Herein, a top‐down strategy, tailoring from the unique linkage basis, flexibility degree, skeleton electronics to trace‐guest adaptability, is proposed to fill the understanding gap between micro‐soft covalent organic frameworks (COFs) and photocatalytic performance. The thio(urea)‐basis‐dominated linkage within benzotrithiophene‐based COFs induce the framework contraction/swelling (intralayer micro‐flexibility) in response to tetrahydrofuran or water. Adaptability of micro‐flexible thiourea‐COF with pore hydrophilicity not only contributes to the favorable mass transfer, but also enhances the accessible redox active sites, culminating in nearly 100% removal of micropollutant with low‐energy dissipation in wastewater. The incorporating urea/thiourea into imine linkage facilitates polarization reduction and exciton dissociation within skeleton wall, inducing strong localization for holes. This transformation facilitates interchain charge transport and unbalanced distribution conducive to oxidative holes‐mediated micropollutant decomposition.

Urea/Thiourea Imine Linkages Provide Accessible Holes in Flexible Covalent Organic Frameworks and Dominates Self-Adaptivity and Exciton Dissociation.

Unraveling the robust self-adaptivity and minimal energy-dissipation of soft reticular materials for environmental catalysis presents a compelling yet unexplored avenue. Herein, a top-down strategy, tailoring from the unique linkage basis, flexibility degree, skeleton electronics to trace-guest adaptability, is proposed to fill the understanding gap between micro-soft covalent organic frameworks (COFs) and photocatalytic performance. The thio(urea)-basis-dominated linkage within benzotrithiophene-based COFs induce the framework contraction/swelling (intralayer micro-flexibility) in response to tetrahydrofuran or water. Adaptability of micro-flexible thiourea-COF with pore hydrophilicity not only contributes to the favorable mass transfer, but also enhances the accessible redox active sites, culminating in nearly 100% removal of micropollutant with low-energy dissipation in wastewater. The incorporating urea/thiourea into imine linkage facilitates polarization reduction and exciton dissociation within skeleton wall, inducing strong localization for holes. This transformation facilitates interchain charge transport and unbalanced distribution conducive to oxidative holes-mediated micropollutant decomposition.

A Review: Recent Advances of Piezoelectric Photocatalysis in the Environmental Fields.

Piezoelectric photocatalysis can effectively suppress the recombination of electron holes during the course of photocatalysis, which has been widely applied in environmental and energy catalysis. Its advantage is that when the piezoelectric effect happens, a built-in electric field is formed inside the catalyst, which improves the separation efficiency of photogenerated charge carriers and obtains more excellent photocatalytic performance. The efficient conversion of mechanical energy to chemical energy can be realized through the synergistic effect of the piezoelectric effect, and photocatalysis is greatly significant in solving the energy crisis and providing environmental protection. Therefore, we organized a more complete review to better understand the mechanism and system of piezoelectric photocatalysis. We briefly introduce the principle of the piezoelectric effect, the existing types of piezoelectric photocatalysts, the practical application scenarios, and the future challenges and feasible methods to improve catalytic efficiency. The purpose of this review is to help us broaden the idea of designing piezoelectric photocatalysts, clarify the future research direction, and put it into more fields of environmental protection and energy reuse.

Microenvironment Engineering of Heterogeneous Catalysts for Liquid-Phase Environmental Catalysis.

Environmental catalysis has emerged as a scientific frontier in mitigating water pollution and advancing circular chemistry and reaction microenvironment significantly influences the catalytic performance and efficiency. This review delves into microenvironment engineering within liquid-phase environmental catalysis, categorizing microenvironments into four scales: atom/molecule-level modulation, nano/microscale-confined structures, interface and surface regulation, and external field effects. Each category is analyzed for its unique characteristics and merits, emphasizing its potential to significantly enhance catalytic efficiency and selectivity. Following this overview, we introduced recent advancements in advanced material and system design to promote liquid-phase environmental catalysis (e.g., water purification, transformation to value-added products, and green synthesis), leveraging state-of-the-art microenvironment engineering technologies. These discussions showcase microenvironment engineering was applied in different reactions to fine-tune catalytic regimes and improve the efficiency from both thermodynamics and kinetics perspectives. Lastly, we discussed the challenges and future directions in microenvironment engineering. This review underscores the potential of microenvironment engineering in intelligent materials and system design to drive the development of more effective and sustainable catalytic solutions to environmental decontamination.

Multifaceted insights into Cu(II) complexes with bis(benzimidazole) ligands: Structural investigation, theoretical studies, cytotoxicity evaluation, and antioxidant summarizing

In this study, the synthesized two new ligands, namely bis(1H-benzo[d]imidazole-1-yl) methane [L1] and 1,2-bis(1H-benzo[d]imidazole-1-yl) ethane [L2], from benzimidazole. They chose 1,2-dibromomethane and 1,2-dibromoethane as they are widely used in environmental catalysis and as ligands in conjugated configurations. The researchers were able to synthesize the Cu(II) complexes, [Cu(L1)2]Cl2 or [1] and [Cu(L2)2]Cl2 or [2], at room temperature. They used several analytical techniques, including elemental analysis, magnetic moment measurement, UV–visible spectroscopy, FT-IR spectroscopy, FT-Raman spectroscopy, NMR spectroscopy (including 1H, 13C, DEPT-135, HSQC, and HMBC techniques), ESI-MS analysis, thermogravimetric analysis, and ESR spectroscopy, to characterize the synthesized compounds. They found that the ESR spectra of complexes [1] and [2] suggest that both metal complexes have square planar coordination spheres. In the DFT study of the geometrical optimization of both complexes, the central plane consists of the Cu metal atom connected to four nitrogen atoms. The Cu–N bond lengths are measured at 2.194 Å for [1] and 2.176 Å for [2] whereas the FMO theory's slight reduction in the HOMO-LUMO gap for [2] suggests that it is more reactive and less stable compared to [1]. In addition, the researchers tested the effect of these compounds on human cervical cancer cell lines (HeLa) which showed significant cytotoxic effects under laboratory conditions. Complex [2] had a significant inhibitory impact on the growth of cancer cells. The researchers also assessed the antioxidant effects of the ligands and metal complexes using DPPH, OH, and NO assays and found that [2] had the most potent inhibitory effect on the radicals, with IC50 values of 36.11 μM (DPPH), 28.18 μM (OH), and 26.20 μM (NO).

CO-Free Fuel Processing of Water Gas Shift Feedstocks: Effect of Support on CuMn Spinel Performance

AbstractCleaning up carbon monoxide (CO) in water gas shift feedstocks is crucial for fuel cell applications. The catalytic transformation of CO in hydrogen-rich feeds poses a significant challenge in environmental catalysis. To address this issue, a range of Cu–Mn-based monometallic and bimetallic catalysts with diverse supports (such as alumina, silica, zirconia, and titania) were employed. Temperature programming techniques were utilised to observe the reduction and oxidation behaviours of these catalysts. The investigation involved testing CO oxidation at various temperatures over copper and manganese-based supported catalysts in the presence of H2O and CO2 (simulating realistic conditions). A positive impact of H2O on catalytic performance was noted, whereas CO2 had a suppressive effect. Furthermore, the specific support materials (Al2O3, SiO2, TiO2, and ZrO2) were studied to understand their roles in CO oxidation under realistic conditions. In the presence of water, alumina catalysts containing bimetallic metals (Cu–Mn) exhibited 100% CO conversion even at a lower temperature of 160 °C. Conversely, under the predominant influence of CO2, alumina catalyst (Cu–Mn) showed 55% CO conversion. The exceptional performance was attributed to CO preferential adsorption on highly active Cu–Mn sites and a small H2-oxidative atmosphere of the catalysts. The activity results highlighted the strong dependence of CO conversion on reaction temperatures, the presence of metals, and the types of supports. Overall, these findings suggest the potential use of these catalysts for H2 purification under realistic conditions. Graphical Abstract

Long-range interactions driving neighboring Fe–N4 sites in Fenton-like reactions for sustainable water decontamination

Actualizing efficient and sustainable environmental catalysis is essential in global water pollution control. The single-atom Fenton-like process, as a promising technique, suffers from reducing potential environmental impacts of single-atom catalysts (SACs) synthesis and modulating functionalized species beyond the first coordination shell. Herein, we devised a high-performance SAC possessing impressive Fenton-like reactivity and extended stability by constructing abundant intrinsic topological defects within carbon planes anchored with Fe−N4 sites. Coupling atomic Fe−N4 moieties and adjacent intrinsic defects provides potent synergistic interaction. Density functional theory calculations reveal that the intrinsic defects optimize the d-band electronic structure of neighboring Fe centers through long-range interactions, consequently boosting the intrinsic activity of Fe−N4 sites. Life cycle assessment and long-term steady operation at the device level indicate promising industrial-scale treatment capability for actual wastewater. This work emphasizes the feasibility of synergistic defect engineering for refining single-atom Fenton-like chemistry and inspires rational materials design toward sustainable environmental remediation.

Regulating iron center by defective MoS2 for superior Fenton-like catalysis in water purification: The key role of surface interaction and superoxide radical in accelerating metal redox-cycling

Transition metals exhibit high reactivity for Fenton-like catalysis in environmental remediation, but how to save consumption and reduce pollution is of great interest. In this study, rationally designed defect-engineered Fe@MoS2 (Fe@D-MoS2) was prepared by incorporating reactive iron onto structural defects generated from the chemical acid-etching, aiming to improve the energetic consumption of the catalyst in Fenton-like applications. Morphological and structural properties were elucidated in details, the Fenton-like reactivity was evaluated with five phenolic contaminants for oxidant activation, radical generation and environmental remediation. Compared to Fe@MoS2, Fe@D-MoS2 exhibited a 18.9-fold increase in phenol degradation (0.09 versus 1.79 min−1). Quenching experiments, electron paramagnetic resonance tests and electrochemical measurements revealed the dominant sulfate and superoxide radicals. Rendered by strong metal-substrate surface and electronic interactions from regulated chemical environment and coordination structure, the inert ≡ Fe(III) was reduced to the reactive ≡ Fe(II) accompanied by the ≡ Mo(IV) oxidation to ≡ Mo(V) in MoS2 lattice, with adjacent sulfur serving as the key electron transfer bridge. Therefore, this work shows that the incorporation of reactive centers is able to boost two-dimensional sulfide materials for environmental catalysis applications.

Ceramics as potential materials in pollution prevention and control

AbstractThe social progress, economic growth, and meteoric urbanization prompt the exploitation of available resources triggering the contagion of the biological and physical elements of the atmosphere irrationally causing global environmental pollution. Environmental contamination monitoring is a dire necessity. Although a number of technologies find mention in the literature for environmental remediation, however, environmental catalysis is an advanced steadily growing technique for pollution abatement. In this dimension, ceramic materials have turned heads due to their wide‐scale application areas. Hitherto, research is being done on advanced ceramics to fabricate novel modules for energy storage applications, in designing green buildings, pollution rheostats, and environmental engineering. This article deals with the abatement of environmental contaminants by adopting various methodologies such as aerobic and anaerobic biological treatments, adsorption, chemical oxidation, membrane separation, photocatalysis, ozonation using the ceramic as precursor materials. The ceramic membranes are cost‐effective, ecofriendly, efficacious, and green approach to obliterate toxins and harmful gases released in environment. Even though, limited literature is available on the abolition of harmful contaminants from air and soil using ceramic materials, an attempt has been made to present currently available data with best of our knowledge. This article will sensitize researchers to refabricate novel materials for environment sustainability.

Challenges and Applications of Supramolecular Metalate Chemistry.

While the supramolecular chemistry of simple anions is ubiquitous, the targeting and exploitation of their metal-containing relatives, the metalates, is less well understood. This mini review highlights the latest advances in this emergent area by discussing the supramolecular chemistry of metalates thematically, with a focus on the exploitation of metalates in a diversity of applications, including medical imaging and therapy, environmental remediation, molecular magnetism, catalysis, perovskite materials, and metal separations. The unifying features of these systems are identified with a view to allow the supramolecular chemist to target the unique material properties of the metalates, even in areas that are currently relatively immature.

Challenges and Applications of Supramolecular Metalate Chemistry

AbstractWhile the supramolecular chemistry of simple anions is ubiquitous, the targeting and exploitation of their metal‐containing relatives, the metalates, is less well understood. This mini review highlights the latest advances in this emergent area by discussing the supramolecular chemistry of metalates thematically, with a focus on the exploitation of metalates in a diversity of applications, including medical imaging and therapy, environmental remediation, molecular magnetism, catalysis, perovskite materials, and metal separations. The unifying features of these systems are identified with a view to allow the supramolecular chemist to target the unique material properties of the metalates, even in areas that are currently relatively immature.

Challenges and Perspectives of Environmental Catalysis for NO x Reduction.

Environmental catalysis has attracted great interest in air and water purification. Selective catalytic reduction with ammonia (NH3-SCR) as a representative technology of environmental catalysis is of significance to the elimination of nitrogen oxides (NO x ) emitting from stationary and mobile sources. However, the evolving energy landscape in the nonelectric sector and the changing nature of fuel in motor vehicles present new challenges for NO x catalytic purification over the traditional NH3-SCR catalysts. These challenges primarily revolve around the application limitations of conventional industrial NH3-SCR catalysts, such as V2O5-WO3(MoO3)/TiO2 and chabazite (CHA) structured zeolites, in meeting both the severe requirements of high activity at ultralow temperatures and robust resistance to the wide array of poisons (SO2, HCl, phosphorus, alkali metals, and heavy metals, etc.) existing in more complex operating conditions of new application scenarios. Additionally, volatile organic compounds (VOCs) coexisting with NO x in exhaust gas has emerged as a critical factor further impeding the highly efficient reduction of NO x . Therefore, confronting the challenges inherent in current NH3-SCR technology and drawing from the established NH3-SCR reaction mechanisms, we discern that the strategic manipulation of the properties of surface acidity and redox over NH3-SCR catalysts constitutes an important pathway for increasing the catalytic efficiency at low temperatures. Concurrently, the establishment of protective sites and confined structures combined with the strategies for triggering antagonistic effects emerge as imperative items for strengthening the antipoisoning potentials of NH3-SCR catalysts. Finally, we contemplate the essential status of selective synergistic catalytic elimination technology for abating NO x and VOCs. By virtue of these discussions, we aim to offer a series of innovative guiding perspectives for the further advancement of environmental catalysis technology for the highly efficient NO x catalytic purification from nonelectric industries and motor vehicles.

Red Mud As the Catalyst for Energy and Environmental Catalysis: A Review

Red Mud As the Catalyst for Energy and Environmental Catalysis: A Review

The Structures and Compositions Design of the Hollow Micro-Nano-Structured Metal Oxides for Environmental Catalysis.

In recent decades, with the rapid development of the inorganic synthesis and the increasing discharge of pollutants in the process of industrialization, hollow-structured metal oxides (HSMOs) have taken on a striking role in the field of environmental catalysis. This is all due to their unique structural characteristics compared to solid nanoparticles, such as high loading capacity, superior pore permeability, high specific surface area, abundant inner void space, and low density. Although the HSMOs with different morphologies have been reviewed and prospected in the aspect of synthesis strategies and potential applications, there has been no systematic review focusing on the structures and compositions design of HSMOs in the field of environmental catalysis so far. Therefore, this review will mainly focus on the component dependence and controllable structure of HSMOs in the catalytic elimination of different environmental pollutants, including the automobile and stationary source emissions, volatile organic compounds, greenhouse gases, ozone-depleting substances, and other potential pollutants. Moreover, we comprehensively reviewed the applications of the catalysts with hollow structure that are mainly composed of metal oxides such as CeO2, MnOx, CuOx, Co3O4, ZrO2, ZnO, Al3O4, In2O3, NiO, and Fe3O4 in automobile and stationary source emission control, volatile organic compounds emission control, and the conversion of greenhouse gases and ozone-depleting substances. The structure-activity relationship is also briefly discussed. Finally, further challenges and development trends of HSMO catalysts in environmental catalysis are also prospected.

Enhancing the Carbon Monoxide Oxidation Performance through Surface Defect Enrichment of Ceria-Based Supports for Platinum Catalyst.

Effective synthesis and application of single-atom catalysts on supports lacking enough defects remain a significant challenge in environmental catalysis. Herein, we present a universal defect-enrichment strategy to increase the surface defects of CeO2-based supports through H2 reduction pretreatment. The Pt catalysts supported by defective CeO2-based supports, including CeO2, CeZrOx, and CeO2/Al2O3 (CA), exhibit much higher Pt dispersion and CO oxidation activity upon reduction activation compared to their counterpart catalysts without defect enrichment. Specifically, Pt is present as embedded single atoms on the CA support with enriched surface defects (CA-HD) based on which the highly active catalyst showing embedded Pt clusters (PtC) with the bottom layer of Pt atoms substituting the Ce cations in the CeO2 surface lattice can be obtained through reduction activation. Embedded PtC can better facilitate CO adsorption and promote O2 activation at PtC-CeO2 interfaces, thereby contributing to the superior low-temperature CO oxidation activity of the Pt/CA-HD catalyst after activation.