The synthesis of cyclic carbonates, which utilizes CO2 as a feedstock, is among the transformations presenting an opportunity to reduce CO2 emissions, while enhancing independence from fossil fuels. Desirability lies in the development of efficient, economically viable and sustainable catalysts for this approach. Many recent publications describe the successful utilization of eutectic solvents/deep eutectic solvents for the synthesis of cyclic carbonates. Nevertheless, the majority of them focuses on reporting catalyst performance (product yield) and reaction conditions (temperature, pressure, reaction time) with little insights into the sustainability aspects (process mass intensity (PMI), solvents, and critical elements involved, as well as health and safety parameters described by H-code). Taking an example of the system composed of naturally occurring, inexpensive tannic acid combined with choline halides, the green chemistry metrics were evaluated for different DESs and other two-component catalysts and discussed in terms of guiding future designs of sustainable catalytic systems for the synthesis of cyclic carbonates.

Chitin, a highly insoluble and poorly degradable polymer derived from seafood industry waste, can be converted into value-added products including N-acetylchitobiose ((GlcNAc)2) and N-acetylglucosamine (GlcNAc) by chitinase, which can overcome the disadvantages of chemical degradation. Here, we identified a novel salt-tolerant chitinase (CHI) involved in chitin degradation from Bacillus clausii TCCC 11004. Recombinant CHI (rCHI) displayed a great tolerance against high concentrations of NaCl, maintaining 376% of its initial activity in a solution containing 0.6 M NaCl, which was about NaCl concentration in seawater. Chitin binding domain (ChBD) engineering demonstrated that rCHI’s ChBD was beneficial for its NaCl resistance property. As a multifunctional chitinase, rCHI exhibited dual exochitinase activity and N-acetylglucosaminidase activity, but no hydrolytic activity toward (GlcNAc)2 when using colloidal chitin as a substrate, which made it different from the typical reported chitinases. As a result, (GlcNAc)2 and GlcNAc achieved the maximum yield ((GlcNAc)2: 25.73 mg/mL and GlcNAc: 3.25 mg/mL) by hydrolyzing colloidal chitin from crab shells using rCHI alone. This study reported a valuable chitinase with the above dual activities and provided an eco-friendly and sustainable approach for cost-effective bioconversion of chitin-containing biowastes to bioactive (GlcNAc)2 and GlcNAc.

Photocatalytic regeneration of valuable cofactors by using sunlight has emerged as a promising strategy for biosynthesis and pharmaceutical manufacturing. Graphitic carbon nitride (g-C3N4) is very suitable for photocatalytic nicotinamide cofactor regeneration since it is metal-free, visible-light responsive and has strong binding with nicotinamide cofactor. However, its great potential is hindered by some intrinsic drawbacks such as low visible absorption, fast electron/hole recombination, and limited active sites. Here, we demonstrate dual-defect g-C3N4 (DDCN) with controllable defects of nitrogen vacancies and cyano groups for efficient photocatalytic cofactor regeneration via a KOH-assisted thermal polymerization by using urea as a precursor. Although DDCN is widely used for other photocatalytic applications such as organic degradation and hydrogen peroxide production, this work is original in its application to photocatalytic cofactor regeneration. Material characterizations confirm the successful introduction of nitrogen vacancies and cyano groups. Measurements of nicotinamide-cofactor generation show that the DDCN samples assisted with 0.1 g and 0.01 g KOH are 3.0 and 2.5 times that of pristine g-C3N4 in terms of nicotinamide cofactor yield, respectively. The high yields are attributed to the synergetic effect of both enhanced light absorption and improved charge separation, achieved through the introduction of energy levels and trap states via dual defects. This work provides a green, energy-saving, and promising strategy for nicotinamide cofactor regeneration and would promote its application in biosynthesis and drug manufacturing.

Electrochemical flow reactors are increasingly relevant platforms in emerging sustainable energy conversion and storage technologies. As a prominent example, redox flow batteries, a well-suited technology for large energy storage if the costs can be significantly reduced, leverage electrochemical reactors as power converting units. Within the reactor, the flow field geometry determines the electrolyte pumping power required, mass transport rates, and overall cell performance. However, current designs are inspired by fuel cell technologies but have not been engineered for redox flow battery applications, where liquid-phase electrochemistry is sustained. Here, we leverage stereolithography 3D printing to manufacture lung-inspired flow field geometries and compare their performance to conventional flow field designs. A versatile two-step process based on stereolithography 3D printing followed by a coating procedure to form a conductive structure is developed to manufacture lung-inspired flow field geometries. We employ a suite of fluid dynamics, electrochemical diagnostics, and finite element simulations to correlate the flow field geometry with performance in symmetric flow cells. The lung-inspired structural pattern is demonstrated to homogenize the reactant distribution in the porous electrode and to improve the electrolyte accessibility to the electrode reaction area. In addition, the results reveal that these novel flow field geometries can outperform conventional interdigitated flow field designs, as these patterns exhibit a more favorable electrical and pumping power balance, achieving superior current densities at lower pressure loss. Although at its nascent stage, additive manufacturing offers a versatile design space for manufacturing engineered flow field geometries for advanced flow reactors in emerging electrochemical energy storage technologies.

The rapidly developing Cu(InGa)Se2 solar cells will face a large amount of scrapping in the next 5–10 years. Waste Cu(InGa)Se2 solar cells are rich in metal and organic resources. Decapsulation is the key step for resource recovery. However, there is a lack of environmentally friendly and efficient decapsulating method. In this study, a combined technology of rich reactive oxygen species and ultrasound was proposed for decapsulating waste Cu(InGa)Se2 solar cells. Ethylene-vinyl acetate, polyethylene terephthalate, and cell layer can be completely separated after 6 h ultrasound-O3 (10 g/h) or 4 h ultrasound-H2O2 (30 wt %) treatment. Under the attack of reactive oxygen species, C–O and C–C bonds in ethylene-vinyl acetate fractured. Structures including −CH3, crosslinking bridge, vinyl acetate side chain, and alkane chain were destroyed. The crosslinked ethylene-vinyl acetate network was damaged, resulting in the adhesion loss. Long-chain and cyclic ketones, esters, and alkane were mainly generated, which are non-toxic natural substances and even have a high value. The O3-ultrasound method can continuously generate reactive oxygen species, excessive O3 can spontaneously decompose into O2, and the solutions can be reused. This study might be the first time to propose the rich reactive oxygen species and ultrasound combined technology for decapsulating waste Cu(InGa)Se2 solar cells, which contributes to the environmentally friendly recovery.

Due to their easy conversion into high-added value products, sugar lactones and their derivatives are very attractive biobased platform molecules. Yet, conventional transformation of free sugars into such activated compounds is not so handy: a multistep procedure requiring protection/oxidation/lactonization-esterification/deprotection is often necessary. We report herein a procedure allowing one to rapidly and efficiently form lactones/esters directly from free sugars under mild conditions, catalyzed with a small amount (0.36 mol %) of recyclable gold nanocatalyst under oxygen atmosphere. The conditions were optimized using galactose as a model, quantitatively and selectively affording 1,4-galactonolactone in 2 h at room temperature. The procedure was then successfully applied to a variety of hexoses and pentoses leading to excellent conversion (>86%). Due to the equilibrium between lactone regioisomers and ester forms, a mixture of 1,4-lactone, 1,5-lactone and methyl ester can be generally obtained depending on the sugar series. A subsequent reaction of the crudes with benzylamine leads to a total conversion of lactones/esters into corresponding amides, confirming the efficiency of the procedure and paving the way to a one-pot transformation of free sugars into high added value sugar-based derivatives. Based on NMR and ESR analyses, a mechanism of the reaction involving CH3O• radical species seems to be taking shape.

Catalytic semihydrogenation of acetylene is crucial for ethylene purification but still faces a grand challenge in circumventing deep hydrogenation and oligomerization so far, especially for the cost-effective catalysts. Herein, two Ni-based intermetallic nanocatalysts with different atomic arrangements were subtly constructed via controlling the reduction temperature of ZnO-supported NiO particles. The one reduced at 400 °C is L12-type intermetallic Ni3Zn with separated Ni3 trimers (denoted as Ni/ZnO-R400 or Ni3Zn/ZnO); another reduced at 600 °C is L10-type intermetallic NiZn with the homogeneous Ni single atoms completely isolated by Zn atoms (denoted as Ni/ZnO-R600 or NiZn/ZnO). The systematical evaluations validate NiZn/ZnO as an outstanding noble metal-free catalyst for acetylene semihydrogenation, showing a significantly enhanced selectivity toward ethylene relative to Ni3Zn/ZnO (87.5 vs −275.4% at 200 °C) through suppressing not only the unselective hydrogenation to ethane but also carbon deposition. According to catalytic evaluations with or without ethylene, microcalorimetry, and density functional theory calculations, the superior selectivity of NiZn/ZnO stems from the noncompetitive adsorption between the moderately σ-bonded acetylene over two neighboring Ni single atoms and weakly π-bonded ethylene on Ni single-atom sites due to its unique Ni–Zn–Ni ensemble.

The oxidation of starch into valuable chemicals holds great promise for the leather industry, but the catalytic efficiency of existing reactions is low. Moreover, residual catalyst in the reaction liquid is a potential environmental hazard. Herein, starch was oxidized by hydrogen peroxide and a magnesium aluminum iron hydrotalcite (MgAlFe-LDH) catalyst to introduce functional groups and nanomaterials, forming a starch-based hydrotalcite composite (OS-MgAlFe-LDH) in one step. This catalyst showed improved catalytic efficiency, and the generation of pollution was avoided. Moreover, the prepared OS-MgAlFe-LDH was suitable as a complex tanning agent for chrome-free tanning with improved efficiency, and MgAlFe-LDH acted as a crosslinking reinforcing agent. Using this tanning agent, the hydrothermal stability of crust leather was enhanced (shrinkage temperature: 75 °C). The tanned leather had high porosity (79.06%) and a uniform tanning agent distribution ascribed to the varying molecular weights of the components of the OS-MgAlFe-LDHs (weight-average molecular weight: 5438 g/mol). The binding energy between OS-MgAlFe-LDHs and the leather collagen (94.62 kcal/mol) was high, inhibiting the migration of OS-MgAlFe-LDHs from the collagen matrix. Thus, OS-MgAlFe-LDHs exhibited strong crosslinking performance with leather collagen. In summary, a sustainable and environmental-friendly tanning agent was prepared by a one-step synthesis in this work, offering a fundamental step for the preparation of biomass materials in the leather industry.

Atmospheric water harvesting is a sustainable solution to global water shortage, which requires high efficiency, high durability, low cost, and environmentally friendly water collectors. In this paper, we report a novel water collector design based on a nature-inspired hybrid superhydrophilic/superhydrophobic aluminum surface. The surface is fabricated by combining laser and chemical treatments. We achieve a 163° contrast in contact angles between the superhydrophilic pattern and the superhydrophobic background. Such a unique superhydrophilic/superhydrophobic combination presents a self-pumped mechanism, providing the hybrid collector with highly efficient water harvesting performance. Based on simulations and experimental measurements, the water harvesting rate of the repeating units of the pattern was optimized, and the corresponding hybrid collector achieves a water harvesting rate of 0.85 kg m–2 h–1. Additionally, our hybrid collector also exhibits good stability, flexibility, as well as thermal conductivity and hence shows great potential for practical application.

Flotation has garnered increasing attention as an indispensable technology for oily wastewater treatment for sustainable and green development. Bubbles are an essential element during the flotation process. Hence, it is important to examine bubble size control in a bubble generator employed in a flotation deoiling system. Herein, a swirling-flow bubble generator was studied via experiments, simulation, and machine learning methods. As the liquid Reynolds number increased from 16,047 to 32,095, the Sauter mean diameter decreased by 27.3%. Compared to the other open-hole schemes, the spiral-bottom open scheme was advantageous in reducing the bubble size, while decreasing the number of open holes reduced the bubble size further. When the surface tension changed from 0.06 to 0.03 N/m, D32 decreased by 27.1%. Decreasing the height diameter ratio and increasing the angle between adjacent holes helped generate more smaller bubbles. However, for a given perforation velocity, the bubble size was insensitive to the size of the open holes. The relationship between D32 and the involved variables was determined accurately by a support vector machine. Finally, a swirling-flow bubble generator with suitable specifications was installed in the flotation deoiling system to achieve an acceptable deoiling performance.

This study presents a sustainable and green method for converting visible light into valuable products. To accomplish this, a Pd NP-doped COF-based magnetic photocatalyst (Pd/CoFe2O4@CTF) was created. The catalytic activity of the heterogeneous photocatalyst was examined in the carbonylative coupling reactions for the preparation of amides, esters, and 2-aryl quinazolinones after it had been characterized using a variety of microscopic and spectroscopic techniques, including FT-IR, PXRD, TGA, SEM, EDAX, TEM, UV-DRS, Matt-Schottky, PL, EIS, ICP, VSM, and BET. This study used the optical method for the first time to create the 2-aryl quinazolinone ring from 2-aminobenzamide and iodobenzene. The desired products can be produced in medium to good yields by using the optical method and under suitable reaction conditions. The benefits of this study include the use of visible light as a renewable and environmentally friendly source, mild reaction conditions, a simple separation method, a reduction in byproducts, and cost and time savings. Under optimal conditions, the catalyst’s stability and recyclability were investigated. It showed excellent reversibility up to 6 times without significantly losing activity.

Platinum (Pt) is a nonrenewable mineral with limited reserves and a patchy distribution. Pt demand and consumption are growing year after year. As a result, recovering Pt from the secondary resources is critical. A new strategy for effective Pt recovery employing Fe(III)-oxalate complexes under UV and visible light irradiation is proposed in this paper. This approach can recover 98.9% of Pt in 30 min under the conditions of 365 nm UV irradiation, leaching time = 30 min, C2O42– concentration = 333.33 g/L, and H2O2 addition = 0.60 vol %. More importantly, 95.6% of Pt can also be recovered in 8 h under sunlight. The homogeneous photocatalytic reaction is rapid and efficient, and meanwhile, no strong acid, base, or volatile toxic organic solvent is required. Additionally, the iron utilized in the process may be well-recycled, solving the problem of recovery difficulty of homogeneous photocatalysts and lowering the cost of leaching. Simultaneously, the Pt complex recovered from the waste catalyst is utilized in situ to manufacture 0.1 wt % Pt/ZSM-5 catalyst, which shows the complete conversion of toluene at 200 °C and can remain stable during the long duration reaction of 1200 min. Overall, it can not only provide a new environmentally friendly technique to recycle Pt from spent catalysts but also save manufacturing cost of new catalysts.

Methane pyrolysis provides an opportunity to utilize abundant fossil fuel resources to produce high quantities of hydrogen with low CO2 emissions. Using a catalytic molten salt bubble column for this reaction is a promising method to reduce the reactor temperature without deactivating the catalyst, producing a separable solid carbon byproduct. Some transition metal chlorides have been examined in recent literature, but there is information lacking as to what properties of the active metal make good catalysts. We show here that the Lewis acidity of the transition metal cation plays a large role in the overall hydrogen production of the melt, with CrCl2 being the most active. Additionally, low-cost salts such as MgCl2 and CaCl2 are moderately catalytic, and catalysis is improved with increasing concentration in the molten solution. Combining the findings of which cationic properties result in a good catalyst offers insight into how the molten salt can be designed to operate for large-scale pyrolysis.

Anion exchange membrane water electrolysis (AEMWE) is one of the most promising technologies for producing green hydrogen; however, they still suffer from durability issues. One task is to find suitable electrolyte conditions for anode catalysts that endow them with both high activity and stability. Herein, we benchmark the pH–stability relationship of four typical metal oxides as anode catalysts in the AEMWE. Their electrochemical performance and structural stability were in-depth analyzed through impedance, dissolved composition in the electrolyte, and correlated Pourbaix diagram. NiFe2O4 with the best activity and stability in the strong alkaline (pH = 14) shows terrible stability in pure water, which is then verified due to the severe Fe leaching, and it cannot be alleviated by alkaline pre-activation. Notably, Co3O4 shows comparable activity and stability to IrO2 in pure water and weak alkaline conditions. At pH = 12, it entails only ∼2.18 V to reach 1.0 A cm–2 and stabilizes for 40 h, being superior to others. This work screens out suitable transition metal oxides as a substitute for noble metals and their optimal application scenarios for AEMWE.

Solar-driven reduction of nitrogen (N2) to ammonia (NH3) offers an alternative carbon-free strategy toward cleaner and more sustainable NH3 production compared with the traditional Haber–Bosch process. However, the photofixation of N2 by low photonic-energy near-infrared (NIR) light still represents a huge challenge. Here, we design an Au/TiO2 hybrid plasmonic system via a solid-state dewetting process to arrange Au nanoparticles uniformly on ordered ultrathin TiO2 nanocavity arrays based on the anodic TiO2 templates, in which the tailored gold nanoparticle arrays serve as the mediator to guarantee NIR light harvesting and energy transfer. The oxidized layer of Ti is rich in oxygen vacancies produced simultaneously in solid-state-dewetting process which facilitates the adsorption and activation of N2 molecules. The charge transfer and N2 reduction reaction are driven in a tandem pathway, leading to an ammonia evaluation rate of 10.1 nmol cm–2 h–1 under NIR irradiation, while the photocatalytic performance shows no obvious decay after a cycle test. Briefly, the NIR-responsive Au/TiO2 plasmonic photocatalyst system opens a new insight to achieve a better utilization of solar energy for photocatalytic nitrogen fixation.

Dynamic covalent polymer networks represent new opportunities in the design of sustainable epoxy resins due to their excellent malleability and reprocessability; however, the adaptable network is usually accompanied by low glass transition temperature, poor creep resistance, and mechanical brittleness. Herein, we demonstrate a vanillin-based hyperbranched epoxy resin (VEHBP) containing disulfide and imine dynamic covalent bonds for recyclable and malleable epoxy resin with high glass transition temperature (Tg), significantly improved creep resistance, and mechanical properties. The dynamic covalent epoxy resin containing 5%VEHBP exhibited a high glass transition temperature of 175 °C and a creep temperature of 130 °C and a 34.1, 19.7, and 173.3% increase in tensile strength, storage modulus, and tensile toughness respectively, compared with the neat resin. Meanwhile, the hyperbranched topological structure of VEHBP complemented by dual dynamic bonds endowed these materials with excellent self-healing ability, reprocessability, and degradability, which represents an important step toward the design and fabrication of high-performance epoxy covalent adaptable networks.

Electrocatalytically reducing gaseous CO2 to high value-added chemical fuels is an ideal method to address energy and environmental issues. To achieve high Faradic efficiency (FE) of specific products with high current density for the CO2 reduction reaction (CO2RR), it is crucial to design suitable electrocatalysts to understand the relationship of structure and performance. Herein, we synthesized a hydrophobic porous carbon scaffold loaded with Au nanoparticles to explore the effect of the porous structure on CO2RR performance. As high as 92% FE of CO is achieved over the optimized 20%Au/FPC-800 electrocatalyst within the applied potential range of −0.7 to −1.1 V versus RHE, and its current density toward CO2RR is also much larger than that of other three electrocatalysts for comparison. Based on the characterization of CO2 adsorption/desorption, Tafel slope, electrochemical impedance spectroscopy (EIS), and in situ attenuated total reflection-surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) analysis, it is proposed that the hydrophobic porous structure favors CO2 storage, which can enhance the mass transfer of low-soluble CO2 molecules to the electrocatalyst interface during CO2RR. Our findings provide a strategy for achieving high FE of converting CO2 to generate a CO product with a high current density.

In electrocatalytic processes, the intimate contact between the catalyst and the electrode is of paramount importance as it contributes to enhancing the catalytic activity. Nafion is a binding material frequently used to achieve this goal. However, its high price, high toxicity, and flammability make its application expensive and environmentally unfriendly. Here we show that xanthan gum (XG), a sugar-derived biopolymer, is a greater alternative and furthermore remarkably improves the electrocatalytic oxidation activity of alcohols and sugars in alkaline electrolytes. The even distribution of the catalyst-XG film on the electrode’s surface and its better mechanical properties drive an intimate contact between the catalyst and the electrode, hence facilitating the electron transfer. In addition, we found that the good hydrophilicity of XG films facilitates the interaction of alcohols and hydroxides with the catalyst, which was supported by DFT calculations. This finding is of crucial importance for industrial applications and environmental considerations. Indeed, the utilization of XG drastically minimizes the cost of electrochemical processes by using less catalyst and due to its nature contributes to protecting the environment.

Photothermal therapy, because of its inherent high specificity and low invasiveness, can easily and quickly inhibit infected wounds and promote repair. Herein, flexible wood (LM) was synthesized and combined with clarithromycin-carrying black phosphorus in a polyvinyl alcohol matrix to create a highly effective photothermal and flexible wood-based hydrogel (LM@PBKb), which exhibited photothermal and photodynamic bactericidal effects as well as long-lasting wound sterility for the treatment of infected skin wounds. The LM@PBKb hydrogel exhibited a photothermal conversion efficiency of 28.8%. When 808 nm laser irradiation and the long-lasting sustained release of the LM@PBKb hydrogel were combined, Escherichia coli was almost completely inhibited. After 808 nm laser irradiation in the near-infrared region, LM@PBKb used in mice with infected wounds rapidly inhibited infection, maintained a sterile environment for a long time, and accelerated wound healing. Scanning electron microscopy images show that the wounds treated with LM@PBKb were relatively flat and resembled uninfected wounds. This highly efficient photothermal flexible wood-based hydrogel is a high-potential environmentally friendly biomaterial.

Rechargeable solid-state sodium–air batteries have been considered as next-generation high-energy-density electrochemical storage devices. However, the limited triple-phase boundaries and slow kinetics between the cathode and electrolyte seriously affect the rate performance and the cycle life of the battery. The cathode/catalyst material of the battery is the facility for oxygen reduction and evolution reactions, which determine the capacity and rechargeability of these metal–air batteries. Herein, we designed a novel two-dimensional porous high-efficiency catalyst (Co0.6@N–C) with high catalytic activity obtained from a cobalt/zinc bimetallic zeolite-like imidazole skeleton structure (Co0.6Zn0.4-ZIF-L) material. The two-dimensional Co0.6@N–C catalyst not only provides more active sites/channels for oxygen adsorption and desorption but also exhibits continuous faster electron transfer at the interface of electrolyte and catalyst; this ingenious arrangement endows the solid-state Na–air battery with a superior capability of 11 150 mAh g–1 and cycling stability in air.