The production of ammonia under ambient conditions has been a long-standing challenge for the chemical industry. The electroreduction of nitrate presents a promising solution for nitrate wastewater treatment and decentralized ammonia production. However, traditional Ag-based catalysts suffer from nitrate-to-nitrite conversion, leading to toxicity concerns and hampering ammonia preparation. In this study, we synthesized an innovative Ag–Cu–P catalyst that effectively tunes the d-band centre and electronic structure. The catalyst exhibited a remarkable NH4+ yield rate of 566.30 μmol cm−2 h−1 at −0.3 V (vs. RHE), reducing nitrite content to below the drinking water standard. Characterization results revealed a distinctive fern leaf-like morphology, providing an expanded active surface area. The challenge of facile nitrate conversion to nitrite on Ag-based catalysts has been addressed through the implementation of electronic structure modulation in this work. Theoretical calculations confirmed the substantial reduction in the energy barrier by modulating the d-band centre and electronic structure, facilitating the conversion of nitrite to ammonia. The regulation and analysis of d-band centres yielded valuable insights for catalyst material design. Meanwhile, direct evidence for potential intermediates has also been presented through in situ spectroscopy. These findings hold significant potential for practical applications, such as enhanced wastewater treatment and decentralized ammonia production, and provide support in the pressing need for sustainable ammonia synthesis under ambient conditions.

Correction for ‘Organocatalytic Friedel–Crafts arylation of aldehydes with indoles utilizing N-heterocyclic iod(az)olium salts as halogen-bonding catalysts’ by Eirini M. Galathri et al., Green Chem., 2023, http://doi.org/10.1039/D3GC03687A.

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Plastic waste is globally ubiquitous and ecologically harmful, but it can be recycled as an abundant carbon source to alleviate worldwide heavy dependence on fossil resources and reduce CO2 emissions. Therefore, research into the chemical recycling of plastic waste has become a critical and pressing area. Compared with polyolefins, polyesters, as represented by PET and PLA, can easily achieve selective depolymerization to their corresponding monomers due to the presence of weaker ester bonds, thus favoring their closed-loop recycling and upcycling. However, comprehensive reviews on this important topic remain scarce, especially from the standpoint of re/upcycling. In this review, we present significant progress in the catalytic depolymerization of different polyesters, including biodegradable polyesters and nonbiodegradable polyesters, and discuss the key factors that limit the efficacies of the different methods and formidable challenges towards closed-loop recycling and upcycling. Such insightful discussion may benefit the further development of advanced strategies to address the problems with the increasing polyester plastic wastes and stimulate their efficient recycling to value-added chemicals and materials.

The utilization of biomass for the production of agricultural green inputs is regarded as a crucial strategy for achieving low-carbon development in agriculture, while also fully harnessing the potential of renewable resources. Pesticides, as a vital agricultural input, often encounter issues pertaining to inefficient usage, resulting in significant environmental pollution and economic losses. As a main component of lignocellulosic biomass, lignin has become one of the most appealing biopolymers for the construction of advanced pesticide delivery systems. This review aims to provide a thorough summary of the advancements in lignin-based controlled release formulations (LCRFs) for the precise delivery of pesticides. The research in this field has experienced rapid growth in the past five years, making it an important area of study. Common LCRFs are introduced, and the factors influencing the release of active ingredients (AIs) within different LCRFs are analyzed. Special emphasis is placed on intelligent-responsive LCRFs, encompassing an overview of the existing formulations and an exploration of their potential application scenarios and development strategies. It is crucial to promote innovation in pesticide formulations based on the actual demands of agricultural production. We hope this review will stimulate the high-value utilization of lignin and the green development of plant protection technologies.

The energy crisis, dependence on non-renewable energy resources and environmental pollution pose a great threat to the ecosystem. Consequently, the generation and utilization of hydrogen as a renewable, pollution-free, sustainable energy resource has attracted significant attention. In this case, different approaches have been explored, among which the electrochemical production of hydrogen through HER provides an efficient, green and clean approach for the mass production of H2. Besides HER, other reactions, such as OER and ORR, are core reactions involved in different electrochemical devices that are being developed to produce green energy technologies. In all these reactions, the development of low-cost materials with high electrochemical activity compared to the state-of-the-art noble metal electrocatalysts is important. Over the last few decades, different catalyst materials have been developed for HER, OER and ORR. Among them, graphene-based materials have been widely explored either as a support material or active catalyst for the above-mentioned electrochemical reactions. Specifically, the intrinsic electrochemical activity of graphene (G) is negligible, and therefore, different strategies, including heteroatom doping, composite development and development of heterojunctions, have been used to improve its electrochemical characteristics for HER/OER and ORR. However, although great advancements have been made using N-doped graphene (NG)-based heterostructures and composites as active electrocatalysts, there is still a lack of understanding of their reaction mechanism and the active sites responsible for the enhanced electrochemical performances are still under debate. Hence, considering the research interest over the past few years on NG-based electrocatalysts, herein we attempt to present a holistic summary of the recent advances made in the synthesis strategies and understanding of the role played by the interface, composite development and active sites in HER/OER and ORR over NG-based electrocatalysts.

Sustainable energy-powered carbon dioxide (CO2) electroreduction into methane (CH4) under ambient conditions holds great promise for achieving carbon neutrality and mitigating environmental pollution. Despite the significant advancements in this field, the unsatisfactory selectivity and stability remain the major obstacles to its large-scale applications. With this background, we present a comprehensive summary of recent progress and future opportunities of CO2 electroreduction into CH4. Firstly, we delve into the elucidation of the reaction mechanism involved in CO2 electroreduction into CH4. A thorough understanding of the individual steps within this process is paramount for designing electrocatalysts and improving selectivity and efficiency. In particular, the development of advanced electrocatalysts (such as copper-based materials, carbon-based materials and other materials) for CO2 electroreduction into CH4 is elaborated. Meanwhile, a special focus has been placed on the enhanced strategies, including coordination environment manipulation, element doping, surface modification, and morphology engineering, for CO2 electroreduction into CH4. Finally, the future challenges of CO2 electroreduction into CH4 are proposed. The review aims to serves as a guiding framework for systematic exploration and optimization of electrocatalysts, thus fostering the development and advancement of CO2 electroreduction into CH4.

Electrochemical carbon dioxide (CO2) reduction can be used to convert CO2 into various compounds at room temperature and ambient pressure using electricity generated from renewable energy sources. This technology is indispensable in establishing an environmentally responsible and sustainable society. However, further improvements in the activity and selectivity require the development of electrocatalysts that can directly serve as the actual reaction sites. In recent years, metal nanoclusters, which are metal particles with a size of approximately 1 nm, have been reported to be capable of electrochemical CO2 reduction with high activity and selectivity, owing to their unique geometric/electronic structure. This review summarizes the synthesis methods of atomically precise metal nanoclusters and their application in electrochemical CO2 reduction. We expect that this review will help clarify the current status of these studies and further accelerate the research on highly active and selective CO2 reduction catalysts using metal nanoclusters.

Using low cost and resource-rich natural materials to develop vital components, especially electrodes, separators, and solid/quasi-solid electrolytes, is of great significance for the commercial application of electrochemical energy storage (EES) devices. Montmorillonite (MMT), although it is a unremarkable traditional clay mineral material, has increasingly attracted widespread interest in the EES field, which is mainly attributed to its low cost, abundant resources, tuneable two-dimensional (2D) layered structure, unique ionic conductive properties, high specific surface area and so on. The focus of this review is to provide a specific and comprehensive summary of the recent progress of MMT-based materials in the field of EES. Firstly, the structure and physicochemical properties of MMT clay are discussed from the perspective of structure–property relationships. Subsequently, the main focus is on the research progress of MMT-based materials in the vital components of EES devices (mainly metal (Li/Na/Zn)-ion batteries, Li–S batteries, and supercapacitors), wherein the role of MMT in different components of EES devices has been elaborated through various characterization analyses and theoretical calculations. Finally, a short conclusion along with some possible future research directions of MMT-based materials in high-performance EES devices is proposed. This review tries to provide beneficial guidance for the practical application of MMT-based functional materials in EES.

There is an urgent need for the development of new water resources in order to solve the problem of the world's growing demand for clean water. Membrane distillation (MD) is a promising alternative to conventional seawater desalination. Although MD itself is often defined as sustainable desalination technology, there are many aspects within the membrane manufacture and process operation that make it far from being green. For instance, non-biodegradable polymers, toxic solvents and fluoroalkyl silanes are typical chemicals that unfortunately are used in membrane fabrication protocols. Additionally, the huge amount of wastewater generated from membrane fabrication processes makes solvent-free methods more attractive and desirable for extensive investigation. Apart from this, the low energy efficiency of the MD process can be effectively overcome by integrating MD systems with low-grade waste heat. This review critically addresses and discusses the recent advances in methods and strategies to improve the sustainability of MD technology, which is not a common scope of study among the research community. Here, our attention has been devoted to the main aspects of MD membrane fabrication, such as polymers, solvents (and their costs), nonsolvents, additives, solvent-free fabrication procedures, fluoro-free post-modification, and MD operation (energy consumption). This review intends to introduce inspiration for membrane scientists for the development of the next-generation MD process, by promoting the sustainable transformation of today's approaches into a greener way. In this latter scenario, we provide some timely considerations that could be followed by the researchers in the field.

This tutorial review aims to describe the status of the scaling up of organosolv treatment. It is a process where various lignocellulosic materials are fractionated, selective depolymerization mechanisms are catalyzed, and their main components (polysaccharides, lignin and extractives) can be extracted, separated and isolated using liquid organic solvents such as alcohols, ketones and proton-donating acid molecules. Organosolv fractionation can be applied to several renewable biomasses, allows the production of pure species systems to prepare valuable chemicals, polymers and biomaterial compositions with a related environmental impact, lower than that of classical industrial plants, and optimizes the resource carbon efficiency. However, the high energy consumption for the recovery after dissolution, input costs and feedstock flexibility robustness are slowing down the piloting of commercial operations. As a critical indicator evaluation, a summary of reasons why engineering organosolv is still extremely interesting, together with an overview of the most important organosolv technologies, describing current equipment scale range economics, limitations and market research opportunities, is presented in detail. A variety of sources (wood, straw, bagasse, wastes…), media (water, methanol, ethanol, formates, acetates…) and products (biogas, bioethanol, (nano)cellulose, glucose, furans…) are comparatively benchmarked. Existing (model) validated, demonstrational or patented configurations are collected, listing strengths as well as challenges.

Some of the latest technological developments involving chemistry in water are discussed. Although each advance bears little-to-no relationship to the others, in the composite they highlight the seemingly unlimited opportunities for discovering nature's secrets using water as the reaction medium. Thus, in addition to the environmental aspects driving this research, the benefits to be realized in making this switch away from reactions run in organic solvents and into an aqueous medium are clearly indicative of the future of synthetic organic chemistry.

The successes achieved in pursuing a nature-aided drug discovery (NADD) program are many and well-known, but it is still considered a second-order approach. Biomass extraction is a fundamental and critical step in the NADD process and often requires a high volume of usually organic and not eco-compatible solvents and a prolonged time. Optimization of such procedures could drastically decrease the costs required for the NADD process, also considering waste management. For this reason, many extraction techniques have been developed, among which one of the most diffused is microwave assisted solvent extraction (MASE). The MASE procedure is well suited for use in the drug discovery phase from natural sources. Still, there are several factors to consider, and the one-factor-at-a-time (OFAT) approach risks limiting the advantages the technique provides. The way to make it truly green is to couple MASE with DoE, even if this winning combination is limited. Consistently, we analyze the 10-year literature (2013–2022), reporting a critical discussion about DoE applied to set up MASE protocols for the extraction of metabolites (both performed with traditional solvents and with ionic and eutectic solvents) and essential oils.

Besides numerous synthetic and biological applications, the catalytic construction of chiral Swaminathan ketones and their analogues possessing a bicyclo[5.4.0]undecane core structure has remained challenging for the scientific community for over four decades. Not more than five Swaminathan ketones (S. ketones) and their analogues are known in the literature to date. Herein, we report an unprecedented organocatalytic asymmetric desymmetrization strategy for the synthesis of chiral S. ketones and their analogues with excellent enantioselectivities from the corresponding 2-alkyl-2-(3-oxobutyl)-cycloheptane-1,3-diones via amine/acid-catalysed conformation-controlled intramolecular aldol condensation. We further reported a neat protocol for the high-yielding synthesis of functionally diverse synthons, 2-alkyl-2-(3-oxobutyl)-cycloheptane-1,3-diones from 2-alkylcycloheptane-1,3-diones via Michael addition. Finally, we also reported the powerful green organocatalytic reductive coupling protocol for generating a huge library of 2-alkylcycloheptane-1,3-diones from the conformationally flexible cycloheptane-1,3-dione and readily available aldehydes, which are potential synthons for the synthesis of bicyclo[5.4.0]undecane skeletons. Constructing a sustainable library of functionally rich chiral S. ketones with excellent enantioselectivities through conformation-controlled intramolecular aldol condensation via asymmetric desymmetrization and their interesting synthetic transformations with high selectivities are the key attractions of this study.

Benzo[b]phosphole oxides are valuable and significant organic functional molecules. Therefore, extensive efforts have been dedicated to the development of an environmentally friendly and convenient synthetic strategy for benzo[b]phosphole oxides. However, several critical issues still persist in the currently available protocols. In this study, we present a direct air-oxidized strategy enabling the transformation of arylphosphine oxides into phosphinoyl radicals, which were further utilized in the synthesis of benzo[b]phosphole oxides by combining with various alkynes. In addition, the results of DFT calculations show that phosphinoyl radical formation could involve an O2-mediated O–H bond homolysis instead of the commonly recognized P–H bond homolysis mechanism.

The selective recovery and utilization of Pd(II) from high-level liquid waste (HLLW) is highly desirable for both a flourishing circular economy and the sustainable development of nuclear energy. However, the design of suitable materials is an ongoing challenge due to the complicated composition and extremely radioactive and acidic conditions of HLLW, which requires exceptional selectivity and structural robustness of materials. In this study, two phenanthroline-based covalent organic polymers are constructed through polycondensation of 1,10-phenanthroline-2,9-dicarbaldehyde and 1,3,5-tris-(4-aminophenyl) triazine (COP-1) and subsequent oxidation of imine to amide groups (COP-2). COP-2 demonstrates a high adsorption capacity (318 mg g−1) and outstanding selectivity for Pd(II) over 17 competing cations at 3 M HNO3 and is stable at high acidity (2–6 M HNO3) and under a strong radiation field of up to 600 kGy γ irradiation. Additionally, COP-2 is reusable without an obvious decrease in adsorption efficiency after 5 cycles and is feasible for use in the dynamic column separation of Pd(II). More importantly, the Pd(II)-loaded COP-2 obtained from adsorption experiments can be employed as a highly efficient heterogeneous catalyst for Suzuki–Miyaura cross-coupling reactions with excellent reusability for more than 20 successive cycles. This work offers an example of turning wastes into wealth by rationally designing materials for precious metal recovery from HLLW and converting them into valuable catalysts.

The synthesis of imides holds significant importance in various scientific disciplines and industrial applications due to their extensive use in biomolecules, inorganic compounds, and organic compounds. Traditional methods for imide synthesis often rely on the use of toxic or expensive oxidizing agents, limiting their sustainability and practicality. Herein, we present a green and environmentally friendly approach for the synthesis of imides from N-alkylamides using electrocatalytic oxidation with H2O as the green oxygen source. This sustainable and atom-efficient approach outperforms traditional methods by eliminating the need for toxic or expensive oxidants while simultaneously achieving high yields under mild reaction conditions. The protocol exhibits broad substrate compatibility, enabling the transformation of a wide range of N-alkyl (methyl, ethyl and cyclopropyl) amides into imides. The resulting imide products can serve as valuable building blocks for the synthesis of biologically relevant 1,2,4-triazole compounds. Furthermore, the practicality of this method is demonstrated through a gram-scale reaction, affirming its efficiency and potential for industrial applications. Our work presents a sustainable and versatile strategy for imide synthesis, aligning with green chemistry principles and sustainable manufacturing practices.

The development of convenient and practical synthetic strategies for constructing bioactive molecules without metal residues is of great interest in organic synthesis. Herein, a metal-free, operationally simple, and scalable electrooxidation-induced three-component cross-coupling method to access 3-thio/selenophosphorylated imidazole derivatives from readily available isothiocyanates/isoselenocyanates, isocyanates, and H-phosphonates is first reported. More than 30 examples have been provided with good to moderate yields. Importantly, the readily accessible compounds could be used as pesticides (wheat anti-locust) with good biocompatibility (5d-stimulated RAW 264.7 macrophages, IL-6 = 5.3 pg mL−1, THF-α = 79.8 pg mL−1), reiterating the importance of the developed electrochemical methodology.