Cost Ability Research Articles

No slowdown of growing season extension with warming in a permafrost‐affected meadow on the Tibetan Plateau

Abstract The Tibetan Plateau holds the world's largest alpine permafrost and is undergoing an acceleration of warming. Phenological shifts over alpine permafrost in a warmer world have been little studied and are greatly underrepresented in current syntheses. Here, we conducted seasonal and gradient temperature‐controlled experiments in a permafrost‐affected meadow to evaluate how warming drives shifts in spring and autumn phenology, and associated growing‐season length at both community and species levels. We found that there is no sign of slowdown in spring advance with warming under a higher year‐around warming treatment, aligning with a future medium warming scenario. Although spring advance led to an advance in autumn senescence according to spring‐only warming experiments, the advance could not offset the delay due to concurrent warming. As a result, year‐around warming significantly delayed autumn senescence, although there was a deceleration in delay with warming under high temperature treatment than under the low one. This finding can be attributed to the possibility that winter warming is insufficient to reduce chilling accumulation, which would not delay spring phenology and then lead to a non‐slowdown in spring phenological advancement. Taken together, there is no slowdown in an extension of growing season length with warming under a higher year‐around warming treatment, with an increase of length by 9 and 21 days at the end of this century under a CO2 stabilization and medium warming scenarios, respectively. Synthesis. Our results suggest that a continued growing season extension at least under the medium warming scenario would help permafrost‐affected meadow ecosystems to mitigate permafrost carbon release on the Tibetan Plateau.

Recent Advances on CO2 Electrochemical Reduction over Cu‐Based Nanocrystals

The electrochemical CO2 reduction reaction (CO2RR) has recently attracted increasing attention of chemists for converting CO2 to value‐added chemicals with the assistance of electrical energy. Over the past decades, substantial efforts have been devoted to CO2RR, however, this process still suffers the challenges of low conversion and poor selectivity to target product due to the thermodynamic stability and kinetic inertness of CO2. Among those catalysts, Cu has been widely used for CO2RR to produce hydrocarbons with relatively high efficiency in spite of the poor selectivity to products. Therefore, it is highly desired to developed highly active and selective Cu based catalysts for CO2RR. This mini‐review will summary the recent advances on CO2RR over Cu‐based nanocrystals (NCs) with a special focus on the control of selectivity of product via surface modification. We hope this mini‐review will motivate chemists to develop efficient catalysts for CO2RR, and also promote the fundamental research on catalyst design in heterogeneous catalysis.

Multi-promoters modified CaO-based sorbent derived from mixed waste slag for long-term CO2 cyclic capture

Calcium looping, a carbon dioxide (CO2) capture technique, may provide an effective route to eliminate climate change brought by the steadily rising anthropogenic CO2 emissions. However, the key challenge for calcium looping is the sintering-induced decay over the numerous cycles for CaO-based sorbents. Herein, multi-promoters modified CaO-based sorbents, derived from the mixed waste slag of marble waste powder (MWP) and rare earth polishing powder wet slag (REPP), are prepared by a simultaneous hydrating and calcining process. The cyclic CO2 capture is explored by a thermogravimetric analyzer, and the promotion mechanism is investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, CO2 temperature-programmed desorption, and reaction kinetics fitting. Results indicate that the multicomponent promoters from the REPP, including CeO2, Ca12Al14O33, and LaPO4, enhance the carbonation cyclic activity of CaO from MWP. The best-performing MWP-REPP sorbent with 15 wt% REPP shows less than a 10 % drop decay and the CO2 carbonation conversion remains at 75 % (0.46 g CO2/g sorbent) after 50 repeated cycles. The excellent cyclic capture performance is attributed to the synergistic interaction between the promoters and CaO, where the CeO2 promoter owns abundant oxygen vacancies, and the Ca12Al14O33 and LaPO4 promoters provide the blocked effect, thus facilitating the CO2 sorption and inhibiting the CaO from sintering. This work presents useful guidance for improving the cyclic sorption stability of CO2 from waste slags.

Implications of Defect Density and Polymer Interactions for CO2 Capture on Amine-Functionalized MIL-101(Cr).

Rising anthropogenic carbon emissions have dire environmental consequences, necessitating remediative approaches, which includes use of solid sorbents. Here, aminopolymers (poly(ethylene imine) (PEI) and poly(propylene imine) (PPI)) are supported within solid mesoporous MIL-101(Cr) to examine effects of support defect density on aminopolymer-MOF interactions for CO2 uptake and stability during uptake-regeneration cycles. Using simulated flue gas (10 % CO2 in He), MIL-101(Cr)-ρhigh (higher defect density) shows 33 % higher uptake capacity per gram adsorbent than MIL-101(Cr)-ρlow (lower defect density) at 308 K, consistent with increased availability of undercoordinated Cr adsorption sites at missing linker defects. Increasing aminopolymer weight loadings (10-50 wt.%) within MIL-101(Cr)-ρlow and MIL-101(Cr)-ρhigh increases amine efficiencies and CO2 uptake capacities relative to bare MOFs, though both incur CO2 diffusion limitations through confined, viscous polymer phases at higher (40-50 wt.%) loadings. Benchmarked against SBA-15, lower polymer packing densities (PPI>PEI), weaker and less abundant van der Waals interactions between aminopolymers and pore walls, and open framework topology increase amine efficiencies. Interactions between amines and Cr defect sites incur amine efficiency losses but grant higher thermal and oxidative stability during uptake-regeneration cycling. Finally, >25 % higher CO2 uptake capacities are achieved for aminopolymer/MIL-101(Cr)-ρhigh under humid conditions, demonstrating promise for realistic applications.

Recent Advances in Photochemical/Electrochemical Carboxylation of Olefins with CO2

Comprehensive SummaryCO2 is an abundant, nontoxic, and renewable C1 feedstock in synthetic chemistry. Direct carboxylation of readily available olefins incorporating CO2 is regarded as a promising strategy to access high value‐added carboxylic acids as well as CO2 fixation. However, due to the thermodynamic stability and kinetic inertness of CO2 and the difficulty in controlling the regioselectivity, the carboxylation of olefins with CO2 still remains challenging. Radical‐type functionalization with olefins represented a powerful protocol and enabled the development of novel transformations in this realm. More recently, the advance of new technology, such as photoredox catalysis and the renaissance of electrochemistry in organic synthesis, offered access to unique chemical reactivities of radical precursors and provided new solutions to the functionalization of olefins. This review presents the recent advances in the radical‐type carboxylation of olefins, which has mainly been achieved through photocatalysis and electrocatalysis in the last decade. In this article, we provide a comprehensive introduction of the progress, summarize the advantages and limitations of current research, and discuss the potential outlook for further development. Key Scientists

Comparison of physicochemical properties between CO2 and CH4 nanobubbles produced by gas hydrate decomposition

Nanobubbles, known for their distinctive physicite and chemical properties, have been successfully applied in various fields. However, the basic properties of nanobubbles formed by gas hydrate dissociation remain poorly understood. In this work, a series of experiments are conducted to investigate the physicochemical properties and stability of CO2 and CH4 nanobubbles produced by hydrate dissociation. The results indicate that the average size of CO2 and CH4 nanobubbles derived from hydrate decomposition slightly increases as the static time prolongs, exhibiting the excellent stability of nanobubbles. Similar to macroscopic bubbles, the size variation of both nanobubble types exhibits a positive correlation with temperature. The absolute value of the surface zeta potential of the CH4 nanobubbles decreases with time, while the opposite is true for the CO2 nanobubbles. Moreover, the expansion in size for both nanobubble types demonstrates a negative correlation with increasing pH, whereas the zeta potential displays a positive correlation with pH. We observed that nanobubble potential is substantially influenced by metal cations within the solution, and the potential effect of CO2 and CH4 nanobubbles was preliminarily discussed by settlement tests as well. These findings may serve as valuable references for future assessments of the role of nanobubbles in reservoir seepage processes and the advancement of gas hydrate technology.

Nano‐engineering in zinc‐based catalysts for CO2 electroreduction: Advances and challenges

AbstractElectrocatalytic CO2 reduction (CO2RR), an emerging sustainable energy technology to convert atmospheric CO2 into value‐added chemicals, has received extensive attention. However, the high thermodynamic stability of CO2 and the competitive hydrogen evolution reaction lead to poor catalytic performances, hardly meeting industrial application demands. Due to abundant reserves and favorable CO selectivity, zinc (Zn)‐based catalysts have been considered one of the most prospective catalysts for CO2‐to‐CO conversion. A series of advanced zinc‐based electrocatalysts, including Zn nanosheets, Zn single atoms, defective ZnO, and metallic Zn alloys, have been widely reported for CO2RR. Despite significant progress, a comprehensive and fundamental summary is still lacking. Herein, this review provides a thorough discussion of effective modulation strategies such as morphology design, doping, defect, heterointerface, alloying, facet, and single‐atom, emphasizing how these methods can influence the electronic structure and adsorption properties of intermediates, as well as the catalytic activity of Zn‐based materials. Moreover, the challenges and opportunities of Zn‐based catalysts for CO2RR are also discussed. This review is expected to promote the broader application of efficient Zn‐based catalysts in electrocatalytic CO2RR, thus contributing to a future of sustainable energy.

Facet and dual vacancy engineering-boosting BiOBr for enhanced CO2 and epoxide cycloaddition reaction under mild and cocatalyst-free conditions: Double substrate active sites and activated surface bromine ions synergy

Among the many strategies for CO2 resource utilization, the synthetic technology of cyclic carbonates with 100 % atom economy through CO2and epoxide is one of the most industrially viable routes, but its efficiency has been severely hampered by the lack of highly active catalytic sites. Moreover, due to the intrinsic thermodynamic stability and kinetic inertia of CO2 and the higher energy barrier of the ring-opening reaction of epoxides, the heterogeneous catalytic conversion of CO2 highly depends on harsh operating conditions, high temperatures and pressures, and the incorporation of cocatalysts. The development of efficient heterogeneous catalysts for CO2 conversion under cocatalyst-free and mild conditions has always been a challenge. Herein, we have proposed a synergetic strategy of facet and vacancy engineering for the construction of highly efficient heterogeneous catalyst BiO1-xBr1-y-(010) for CO2 cycloaddition, where introducing the OVs-BrVs pairs into typical (010) facets BiOBr with simultaneous surface Lewis acid sites Bi3+ and nucleophilic sites Br−. By combining theoretical calculations and a series of systematic experiments, such as CO2 temperature-programmed desorption, electron paramagnetic resonance and fluorescence probe analysis experiments, the introduced OVs-BrVs pair can not only form Bi3+-Bi(3-x)+ dual active sites on the surface, which activate PO and CO2 respectively to reduce the energy barrier of CO2 insertion, but also activate Br− near BrVs to enhance their nucleophilic attacking ability and reduce the energy barrier of epoxides ring-opening. As a result, the BiO1-xBr1-y-(010) with abundant surface OVs-BrVs pairs showed a high cyclic carbonates conversion of 99 % with 100 % selectivity under cocatalyst-free and mild conditions, far surpassing most heterogeneous catalytic systems. This work provides a completely new strategy to construct high-performance heterogeneous CO2 cycloaddition catalysts through a simple facet and vacancy engineering strategy to overcome the harsh operating conditions limitation and the use of cocatalysts.

Ca substitution in Ca1‐xSrxTi0.8Fe0.2O3‐δ perovskites for oxygen transport membranes: A promising strategy to improve CO2 tolerance

AbstractOxygen transport membranes (OTMs) can be operated as efficient oxygen separators and oxygen distributors, but their diffusion is hampered by the lack of appropriate materials with sufficient chemical stability in operating conditions. Mixed ionic‐electronic conducting SrTiO3‐based perovskite are a promising option due to their remarkable resistance in reducing environments, but they are prone to degradation in CO2‐containing atmospheres owing to carbonate formation. In this study, we propose new Ca1‐xSrxTi0.8Fe0.2O3‐δ perovskites where the Sr2+ cation is partially substituted by Ca2+ to improve the tolerance to CO2. We show that, upon increasing Ca molar fraction, the phase stability in CO2 is progressively improved thanks to the mitigation of carbonate growth. The manufacturing process of the membranes benefits from Ca introduction, which promotes powder densification during sintering. A membrane made of Ca0.1Sr0.9Ti0.8Fe0.2O3‐δ exhibited a stable oxygen flux for 340 h at 900°C when swept with He and for 170 h at 900°C when swept with a gaseous stream containing 40% CO2. Post‐test characterizations confirmed the retention of the crystal structure after the long‐term permeation tests. Ca‐substituted SrTi1‐yFeyO3‐δ perovskites can be considered promising materials for OTMs working in harsh environments and in the presence of CO2.

Stability of CO2 Fluid in Eclogitic Mantle Lithosphere: Thermodynamic Calculations

Findings of solid and liquefied CO2 in diamonds from kimberlites and placers have indicated its presence in the form of a fluid phase in the Earth’s mantle at depths of 150–250 km. However, this is inconsistent with the results of experiments and existing thermodynamic calculations. To clarify this, we carried out thermodynamic modeling of garnet–CO2 and bimineral eclogite–CO2 systems using the Perple_X v. 7.1.3 software package, which establishes the most thermodynamically favorable assemblages for a given bulk composition of the system, unlike previous calculations, for which the phase relationships were simply assumed. The key difference between our results and previously known data is the presence of a region of partial carbonation. In this region, the garnet and clinopyroxene of the new compositions, CO2 fluid, carbonates, kyanite, and coesite are in equilibrium. The calculations revealed that unlike endmember systems (pyrope–CO2 and diopside–CO2) in the eclogite–CO2 system, the carbonation and decarbonation lines do not coincide, and the Grt+Cpx+CO2 and Carb+Ky+Coe+Cpx fields are separated by the Grt+Cpx+CO2+Carb+Ky+Coe region, which extends to pressures exceeding 4.3–6.0 GPa at 1050–1200 °C. This should extend the CO2 stability field in the eclogitic mantle to lower temperatures. Yet, owing to the short CO2 supply in the real mantle, the CO2 fluid should be completely spent on the carbonation of eclogite just below the eclogite + CO2 field. Thus, according to the obtained results, the CO2 fluid is stable in the eclogitic mantle in the diamond stability field at temperatures exceeding 1250 °C and pressures of 5–6 GPa.

Thermally stable Ni foam-supported inverse CeAlOx/Ni ensemble as an active structured catalyst for CO2 hydrogenation to methane

Nickel is the most widely used inexpensive active metal center of the heterogeneous catalysts for CO2 hydrogenation to methane. However, Ni-based catalysts suffer from severe deactivation in CO2 methanation reaction due to the irreversible sintering and coke deposition caused by the inevitable localized hotspots generated during the vigorously exothermic reaction. Herein, we demonstrate the inverse CeAlOx/Ni composite constructed on the Ni-foam structure support realizes remarkable CO2 methanation catalytic activity and stability in a wide operation temperature range from 240 to 600 °C. Significantly, CeAlOx/Ni/Ni-foam catalyst maintains its initial activity after seven drastic heating-cooling cycles from RT to 240 to 600 °C. Meanwhile, the structure catalyst also shows water resistance and long-term stability under reaction condition. The promising thermal stability and water-resistance of CeAlOx/Ni/Ni-foam originate from the excellent heat and mass transport efficiency which eliminates local hotspots and the formation of Ni-foam stabilized CeAlOx/Ni inverse composites which effectively anchored the active species and prevents carbon deposition from CH4 decomposition.

Electrochemical properties of Sr-doped La2-xSrxCe2O7-δ hydrogen separation membrane

The prominence of hydrogen energy has brought membrane separation technology to forefront attention. La2Ce2O7, possessing a fluorite structure, exhibits notable stability in both H2O and CO2, rendering it a prospective material for membrane separation. The impact of Sr doping on the electrochemical characteristics of La2Ce2O7 was systematically investigated. The findings indicate that a minor addition of Sr2+ through doping enhances the electrical conductivity, with the most significant improvement observed in La2-xSrxCe2O7-δ (x = 0, 0.05, 0.15, 0.30) when doped by 0.05. Elevated temperature and increased hydrogen partial pressure on the feed side enhance hydrogen permeability. Hydrogen permeation is predominantly governed by bulk diffusion when the membrane thickness exceeds 0.59 mm, while for thicknesses below 0.49 mm, the process is influenced by both surface and bulk diffusion. Moreover, the doped La2Ce2O7 exhibit commendable stability in H2O and CO2 environments. Consequently, La2Ce2O7 emerges as a promising candidate for ceramic hydrogen separation membranes.

SnO2 nanodots-embedding and KSCN-assisted re-calcination synergistically boost photocatalytic CO2 reduction of carbon nitride

In this work, a heterojunction of SnO2 nanodots embedded on K-doped carbon nitride (CN) was prepared via wet chemistry and two-step calcination processes for photoreduction of CO2. Experiments and theoretical calculations confirmed that both of SnO2-embedding and KSCN-assisted re-calcination could enhance visible light absorption and facilitate photogenerated charge separation, enabling constructed SnO2/K-CN had good CO2 adsorption and activation performances. The optimized photocatalyst loaded with 1.92 wt% SnO2 displayed high CO2 reductive activity with CO and CH4 yields of 80.4 and 1.4 μmol g−1, respectively after 3 h in the presence of 0.5 mL water. Such CO2 reductive activity was not reduced in four repeated tests within the 45 day period. This work provides a new method to construct CN-based heterojunction for enhancing CO2 reductive capacity and stability.

MOFs-derived Ni@ZrO2 catalyst for dry reforming of methane: Tunable metal-support interaction

Metal-support interaction (MSI) plays an important role in heterogeneous catalysis, that could be well regulated by many strategies. Here, Ni@ZrO2 catalysts were controllably synthesized by sacrificial Zr-MOFs template strategy, and were applied to the dry reforming of methane (DRM). Amongst, the Ni/ZrO2-B catalyst shows the best performance toward CH4 and CO2 conversion, H2/CO ratio, and stability, following by Ni/ZrO2-A and Ni/ZrO2C catalysts. The difference in catalytic performance should be ascribed to different synthetic strategy, resulting in different properties of Ni species and ZrO2 matrix, and interface interaction. It revealed that small Ni particles were benefit for CH4 activation, and strong MSI boosted CO2 activation, that could remain the Ni dispersion and thermal stability. This study is beneficial to the catalyst design in DRM reaction.

Recent Advances in Hydrogenation of CO2 to CO with Heterogeneous Catalysts Through the RWGS Reaction.

With the continuous increase in CO2 emissions, primarily from the combustion of coal and oil, the ecosystem faces a significant threat. Therefore, as an effective method to minimize the issue, the Reverse Water Gas Shift (RWGS) reaction which converts CO2 towards CO attracts much attention, is an environmentally-friendly method to mitigate climate change and lessen dependence on fossil fuels. Nevertheless, the inherent thermodynamic stability and kinetic inertness of CO2 is a big challenge under mild conditions. In addition, it remains another fundamental challenge in RWGS reaction owing to CO selectivity issue caused by CO2 further hydrogenation towards CH4 . Up till now, a series of catalysis systems have been developed for CO2 reduction reaction to produce CO. Herein, the research progress of the well-performed heterogeneous catalysts for the RWGS reaction were summarized, including the catalyst design, catalytic performance and reaction mechanism. This review will provide insights into efficient utilization of CO2 and promote the development of RWGS reaction.

Progress and Perspectives in the Development of Inorganic-Carbonate Dual-Phase Membrane for CO2 Separation

The inorganic-carbonate dual-phase membrane represents a class of dense membranes that are fabricated using diverse support materials, ranging from metals to ceramics. This dual-phase membrane consists of a porous metal or ceramic support with an introduced carbonate phase within the support pores. Compared with polymer and zeolite membranes, inorganic-carbonate dual-phase membranes exhibit exceptional CO2 selectivity at elevated temperatures (>500 °C), making them an ideal choice for high-temperature CO2 separation in power plant systems. The present paper provides a comprehensive overview of the separation principle, significant models, and preparation techniques employed in carbonate dual-phase membranes for CO2 separation. The present study aims to discuss key factors that limit the CO2 permeation performance and stability of membranes, while also exploring the potential applications of dual-phase membranes in various fields. The identification of key challenges in the future development of the carbonate dual-phase membrane has been highlighted in this work. The future trajectory of research and development should be directed toward overcoming these challenges, encompassing the synthesis technology of membranes, balance optimization of membrane structure and performance, modification of physical and chemical properties of molten carbonate, and advancement in high-temperature sealing techniques, as well as exploration of diverse membrane reactors based on carbonate dual-phase membranes for prospective applications.

Cobalt catalyzed ethane dehydrogenation to ethylene with CO2: Relationships between cobalt species and reaction pathways

TiO2, ZrO2 and a series of TiO2-ZrO2 (TxZ1, x means the atomic ratio of Ti/Zr = 10, 5, 1, 0.2 and 0.1) composite oxide supports were prepared through co-precipitation, and then 3 wt% Co was loaded through wetness impregnation methods. The obtained 3 wt% Co/TiO2 (3CT), 3 wt% Co/ZrO2 (3CZ) and 3 wt% Co/TxZ1 (3CTxZ1) catalysts were evaluated for the oxidative ethane dehydrogenation reaction with CO2 (CO2-ODHE) as a soft oxidant. 3CT1Z1 catalyst exhibits excellent catalytic properties, with C2H4 yield, C2H6 conversion and CO2 conversion about 24.5 %, 33.8 % and 18.0 % at 650 °C, respectively. X-Ray Diffraction (XRD), in-situ Raman, UV–vis diffuse reflectance spectra (UV–vis DRS), H2 temperature-programmed reduction (H2-TPR), Electron paramagnetic resonance (EPR) and quasi in-situ X-ray Photoelectron Spectroscopy (XPS) have been utilized to thoroughly characterize the investigated catalysts. The results revealed that 3CT1Z1 produced TiZrO4 solid solution with more metal defect sites and oxygen vacancies (Ov), promoting the formation of Co2+-TiZrO4 structure. Furthermore, the presence of Ov and Ti3+can facilitate the high dispersion and stabilization of Co2+, as well as suppressing the severe reduction of Co2+, leading to superior ethane oxidative dehydrogenation activity. Besides, less Co0 is beneficial to ODHE reaction, because of its promotion effects for reverse water gas shift reaction; however, more Co0 results in dry reforming reaction (DRE). This work will shed new lights for the design and preparation of highly efficient catalysts for ethylene production.

Experimental and neural network prediction of the cyclic stability and light absorption characteristics of supercritical CO2 based CNTs nanofluids

Traditional working fluids face challenges including constrained heat transfer efficiency and inadequate thermal stability, which are detrimental to the thermal efficiency of energy conversion systems. To overcome these limitations and achieve a profound breakthrough in the field of energy conversion, it is imperative to develop innovative working fluids. Consequently, this study builds a nanofluid circulation flow experimental platform and prepares a supercritical carbon dioxide/hydroxylated multi-walled carbon nanotubes nanofluid. The study conducts a series of meaningful experimental tests and performance predictions, including stability analysis, deposition characterization research, light absorption potential investigation, and artificial neural network prediction. Remarkably, the artificial neural network model exhibits excellent learning capacity in training, validation, and testing, with root mean square error of only 9.069 W/m2, 8.9996 W/m2, and 13.0143 W/m2, respectively. Test results indicate that the nanofluid reaches a steady state after 4 min, with a fluctuation amplitude of only 2.13 %. Furthermore, the deposition density of the nanofluid on nickel sheet saturates after 4 h, confirming its considerable potential for promotion and application. The light absorption capacity and power decay rate of the nanofluid are enhanced by 606–881 W/m2 and 32.3–46.99 %, compared to other typical substances. The transmittance is reduced by 8.51–22.96 % compared to other nanofluids. The nanofluid proves to be an effective alternative to conventional working fluids, providing a practical reference solution for researchers aiming to improve working fluids in the field of energy conversion.

Exploring the stability and catalytic activity of monoethanolamine functionalized CuO electrode in electrochemical CO2 reduction.

Electrochemical carbon dioxide reduction reactions (eCO2RR) have emerged as promising strategies for both mitigating CO2 emissions and converting them into valuable products. Despite the promise, challenges such as stability, efficiency, and availability of CO2 on the electrode surface, especially at high current densities, still need to be overcome. Herein, this study explores the precipitation of CuO nanoparticles with monoethanolamine to preserve nitrogen groups on the surface of the material. These groups can act by adsorbing the CO2 and stabilizing its catalytic performance during the electroreduction procedure. The incorporation of monoethanolamine as functionalization on the surface of the CuO catalyst was confirmed by XPS measurements. Electrodes utilizing the S-MEA catalyst demonstrated enhanced electrochemical activity, achieving a current density of -187 mA cm-2 at a half-cell potential of -1.2 V versus RHE. Furthermore, long-term stability tests confirmed consistent activity for at least 100 hours in both flow cell and zero gap cell configurations. These results indicate that electrodes featuring the S-MEA catalyst display notably superior electrochemical activity and stability compared with the non-functionalized CuO (S-KOH) and commercial CuO nanopowder (c-CuO). The S-MEA enhancement is attributed to the introduction of amine functional groups that serve as CO2 adducts, facilitating CO2 adsorption and fostering electrode activation. It was evidenced by higher current densities and improved structural integrity during prolonged tests. The insights gained from the comparative performance of these electrodes provide valuable directions for future research in developing more robust and efficient catalysts for environmental remediation technologies.

Isoreticularity in a gallate-based metal–organic framework: Impact of the extension of the ligand on the porosity, stability and adsorption of CO2

Isoreticularity is one of the key aspects in the design of new Metal-Organic Frameworks (MOFs), but has been up to now scarcely applied to gallate (1,2-3-trioxobenzene) ligands. With the aim of building new materials isoreticular to the M(Hngal) (H4gal = gallic acid) small pore MOF series, we here designed the new elongated mixed gallate-carboxylate ligand 4-(3,4,5-trihydroxyphenyl)benzoic acid (H4bpgal). A thorough investigation of its reactivity with MgCl2 has led to the successful isolation of the targeted material Mg(H2bpgal)·n(solv) (solv = water, methanol, ethanol). A combination of experimental tools, including single-crystal X-ray diffraction (XRD), powder XRD, and 1H and 13C solid-state NMR studies confirmed the close structural relationship with the smaller analogue, including the presence of acidic OH sites arising from phenol groups bound to Mg cations. Contrary to the small pore analogue, Mg(H2bpgal) is of limited interest for gas capture, because of its moderate stability upon exposure to dioxygen and low affinity for CO2, both resulting from the intrinsic characteristics of the ligand (redox activity and flexibility, respectively). Nevertheless, it presents among the highest surface area and pore volume reported to date for a gallate MOF (1475 m2 g−1 and 0.59 cm3 g−1, respectively); these characteristics might be of interest in other fields of applications, including electrochemical energy storage or combined controlled drug release.