Exploiting its exceptional structural tunability and digital manufacturing capability, 3D printing emerges as a transformative technique for the rational design and scalable fabrication of catalytic electrodes tailored for advanced electrochemical energy systems. In this study, hierarchically porous, self-supporting carbon electrodes were fabricated via 3D printing technique in combination with the sequential conformal carbonization. An optimized polymerizable ionic liquid-based ink was employed to produce a 3D printed polymer gel, which was subsequently functionalized with B-containing species. The as-prepared gel was then pyrolyzed to yield B/N-co-doped carbon electrodes with a high surface area possessing micropores, mesopores and macropores. The metal-free cathode demonstrated good performance in electrocatalytic CO₂ reduction, producing syngas with tunable H₂/CO ratios ranging from 0.37 to 2.6, thereby catering to diverse application requirements. This study naturally integrates 3D printing with ionic-liquid chemistry to fabricate customizable metal-free carbon electrodes for efficient CO₂-to-syngas conversion, offering a Power-to-X route to store intermittent renewable electricity as chemical energy and to deliver tunable H₂/CO syngas suitable for downstream fuel and chemical synthesis.

A new approach for characterizing paramagnetic sites in materials is introduced. It combines broadband fast magic-angle spinning (MAS) NMR data with ab initio computed paramagnetic NMR shifts using correlated wave functions. This study presents a challenging example of this. With Fe coordinated in a model compound, the PCN-224 porphyrin metal–organic framework (Fe@PCN-224 MOF) was used to elucidate the coordination geometry and electronic structure using ¹H and ¹³C MAS NMR spectra of the ligand atoms. The computationally predicted ¹³C NMR shifts on the paramagnetic Fe@PCN-224 MOF compared unprecedentedly well with experimental ¹³C NMR shifts and equally well for the diamagnetic counterpart, the Fe-free PCN-224 MOF. This is despite the 25 times wider NMR shift range of 1200 ppm for the paramagnetic Fe@PCN-224 MOF. We conclude that this approach is applicable to crystalline, noncrystalline, and molecular systems.

Direct air capture (DAC) is an emerging technology that supports mitigating climate change. However, its large-scale deployment is hindered by high energy demands and material costs. In this study, we present a novel porous sorbent material for DAC using 3D-printed activated carbon monoliths functionalized with an aminosilane compound. The monoliths were fabricated via direct ink writing and subsequently modified with 3-aminopropyltriethoxysilane (APTES) to introduce chemisorption sites for CO₂. Structural and chemical analyses confirmed successful grafting of amines without compromising the monolithic architecture. The resulting monoliths demonstrated enhanced CO₂ uptake at atmospheric concentrations (0.25 mmol g⁻¹ at 0.04 kPa). IR spectroscopy revealed that the functionalized monoliths chemisorb CO₂ from ambient air as ammonium carbamate. Chemisorbed CO₂ can be desorbed at a temperature of 75°C, indicating a low energy requirement for a DAC process. To the best of our knowledge, this paper is the first published application of aminosilane-functionalized activated carbon for DAC, highlighting its potential as a cost-effective and scalable sorbent material.

Upcycling plastic waste into valuable resources without solvents, precious metals, or additional H₂ under mild conditions is a formidable challenge that requires new innovations. Herein, we document a catalyst based on Al₂O₃ beads and zeolite ZSM-5 (ZSM-5#Al₂O₃(2 h)). It cracked polyethylene (PE) into gasoline-range C₄ − C₁₂ hydrocarbons with a selectivity of 98% and a yield of >71% within 1.5 h at 260 °C. Characterization of the catalysts revealed a mesoporous structure and suitable Brønsted acid sites, which promoted the diffusion and catalytic activation of PE. Adjusting the dosage of zeolite supported on Al₂O₃ beads enables regulation of both the number and strength of acidic sites. Theoretical calculations confirmed that the interfacial interaction between zeolite ZSM-5 and Al₂O₃ reduces the acid strength of the composite. This is beneficial for the formation of higher hydrocarbons. Remarkably, the process was performed in a 1 L CSTR unit. These results provide  instructive guidance for the design of high-performance catalytic materials used in PE waste recycling.

We hypothesize that dynamic aspects of the chemisorption of CO2 and co-adsorption of H2O on aminated adsorbents are highly important when used in direct air capture (DAC) technologies. In DAC, a key challenge is to selectively capture CO2 from ambient air at a concentration of 0.04 % CO2 in the presence of competing gases. Two aminated porous adsorbents, namely porous poly(ionic liquid) networks (termed “Polymer 3.0′') and three aminated (mono-, di-, and triamine-functionalized) porous silica-based sorbents, were tested and compared with the commercially available CO2 adsorbent Lewatit VP OC 1065. Both static and dynamic adsorption experiments were performed, in addition to textural and elemental analysis of the adsorbents. The CO2 adsorption and co-adsorption of H2O, and their temperature-dependence were studied in detail by dynamic adsorption experiments. A strong correlation was identified between CO2 adsorption and two key factors: the number of amino groups and the specific surface area of the adsorbents. The latter alone was not always sufficient for determination of the CO2 adsorption capacities. A positive correlation between the adsorption of CO2 and H2O was observed for all the sorbents, which is in turn related to either the specific surface area or the number of accessible amino groups. Our results show that in comparison to pure CO2, the co-adsorption of CO2 and H2O increased the CO2 uptake, and that the CO2 capacity decreased at higher temperatures as expected from the exothermic nature of adsorption. Comparative static and dynamic adsorption analyses demonstrated that both approaches are important for the characterization and evaluation of CO2 adsorbents.

Direct air capture (DAC) is a promising negative-emission technology for mitigating climate change caused by excessive atmospheric CO2 emissions. Amine-functionalized solid adsorbents exhibit a strong affinity for CO2 in ambient air, making them attractive for DAC systems. However, their regeneration for reuse typically requires a high energy use during thermal swing processes. Herein, we upcycle wood waste into a DAC adsorbent that can release CO2 via solar light irradiation for an energy-saving DAC process. Importantly, the as-synthesized adsorbent in situ preserves lignin, enabling photothermal heating without addition of photothermal fillers into a complex composite. The as-synthesized adsorbent exhibits a CO2 uptake of 1.84 mmol/g at 25 °C, rapidly reaching 50% of its capacity within 7 min, and releasing 50% of CO2 in 22 min at 67 °C under solar illumination. Moreover, this study found the presence of water vapor enhances the CO2 adsorption capacity of the adsorbent, making it particularly advantageous for CO2 capture under humid air conditions. This work demonstrates a straightforward approach for developing solar-driven regenerative CO2 adsorbents based to a large fraction on waste lignocellulosic biomass, offering a promising pathway to sustainable and energy-efficient DAC.

Efficient and durable biocatalysts are important for sustainable CO₂ capture technologies, but enzyme stability often limits their use under harsh process conditions. Here, we evaluate carbonic anhydrases (CAs) adsorbed onto aminated mesoporous SBA-15 as biocatalysts for CO₂ capture under the hypothesis of adsorption-induced thermal stabilization. Carbonic anhydrase from the thermophilic bacterium Persephonella marina (pmCA) and commercial bovine erythrocyte carbonic anhydrase (bCA) were used. Enzyme adsorption isotherms for pmCA and bCA onto the aminated SBA-15 were established, along with desorption tests. Adsorbed and free pmCA and bCA were incubated at 40–90 °C for 14 d. The structural integrity and possibility of amine leaching of the incubated (90°, 14 d) aminated SBA-15 were analyzed by X-ray diffraction (XRD) and NMR spectroscopy. The reaction product speciation in CO₂-loaded catalyzed and uncatalyzed dispersions was monitored using infrared (IR) spectroscopy. The maximum enzyme adsorption capacities were established to be 1.4 ± 0.2 g pmCA·g-aminated SBA-15^–1 and 2.1 ± 0.5 g bCA·g-aminated SBA-15^–1, with no detectable desorption. Adsorbed pmCA and bCA maintained high activity for 14 d at 40–65 °C and for 4 d at 90 °C, whereas free enzymes lost activity within 4 d at all temperatures. The XRD patterns of the heat-treated (90 °C, 14 d) aminated SBA-15 indicated a full collapse of the mesostructure. IR spectroscopy confirmed enhanced HCO₃^– formation in the presence of immobilized CA. Overall, enzyme adsorption onto the aminated SBA-15 significantly improved the thermal stability and activity of pmCA and bCA compared to the free enzymes, demonstrating the potential of adsorbed CAs for biocatalysis.

Given the substantial emissions of CO₂ into the atmosphere, there is a critical need for effective CO₂ adsorbents at scale, ideally derived from abundant and sustainable natural resources. In this work, microcrystalline cellulose derived from cotton is used to fabricate cellulose aerogel as porous support via a NaOH/urea-based dissolution and regeneration process, followed by surface modification with a series of amino silane coupling agents to produce aminated cellulose aerogel as CO₂ adsorbent. The as-synthesized optimal adsorbent exhibits a high CO₂ sorption capacity of up to 1.5 and 1.3 mmol g⁻¹ at 0 °C and 25 °C at 1 bar, respectively. Notably, in-depth analysis shows that the adsorbent achieves an impressive capacity of CO₂ uptake of 0.29 mmol g⁻¹ at 25 °C at an exceptionally low CO₂ pressure of 0.4 mbar, i.e., under ambient CO₂ pressure. It implies its potential use as adsorbent both for the traditional point-source capture and the direct air capture as an emerging negative emission technology. This study underscores the environmentally friendly, cost-effective, and biosourced attributes of aminated cellulose aerogel as a compelling alternative for carbon capture, contributing to global initiatives combating CO₂ emissions and stressing the key role of sustainable materials in tackling this global environmental challenge.

This study focused on CO₂-triggered phase separation in concentrated dispersions of mono-, di-, and triaminated silica for CO₂ capture, based on the hypothesis of reduced regeneration energy coupled with the formation of a CO₂-rich, water-lean sediment. The sedimentation of the CO₂-rich and CO₂-lean dispersions was studied using time-resolved optical transmittance measurements. The CO₂ capacity, reaction rate, diffusivity, and solubility of the dispersions were also studied. The involved CO₂-amine chemistry was studied by using infrared (IR) and cross-polarization solid-state ¹³C and ¹⁵N NMR spectroscopy, and the fluid behavior of the dispersions was studied by rheology. The aminated silica was of the SBA-15 type and characterized by N₂ adsorption and desorption experiments, thermogravimetric analysis, powder X-ray diffraction, scanning and transmission electron microscopy, and crosspolarization solid-state ²⁹Si NMR spectroscopy. The derived energy balances for a simplified process indicated that the regeneration of the CO₂-rich sediments results in an energy demand similar to that of 30 wt % ethanolamine (MEA) in water. The bounds of the energy balances were found to be limited by the somewhat low CO₂ capacities of the dispersions, which underscores the need for increasing the amino group density of the dispersions in future efforts. The observed changes in transmittance between the CO₂-lean and CO₂-loaded dispersions showed that sedimentation occurred within the first 10 min for the CO₂-loaded dispersions, while the CO₂-lean dispersions exhibited no change in transmittance after 60 min. The analysis of the pressure decay curves of the partial CO₂ pressure showed that the absorption rates of the dispersions were smaller than those of monoethanolamine (MEA) in water but were similar to the absorption rates of 2-amino-2-methyl-1-propanol (AMP) in water. The IR spectroscopic analysis was consistent with the formation of ammonium carbamates at a low CO₂ loading and the subsequent formation of HCO₃^– at a higher loading. The flow curves displayed rich and complex fluid behavior, which was strongly affected by the capture of CO₂ by the dispersions. Phenomena such as shear thinning, jamming, and thixotropy were observed.

Generating hydrogen peroxide (H₂O₂) within aqueous or eco-friendly solvent systems presents significant challenges due to the complex reaction dynamics and the need for highly selective and stable catalysts. Herein, we report the production of H₂O₂ with an exceeding rate of one millimole per liter per hour in the absence of catalysts, achieved by agitating aerated ethanol-aqueous solutions with ultrasound. This result is attributed to the water charge transfer, which induces charged water molecules to react with dissolved oxygen and ethanol, respectively. In addition, the diffusion of the superoxide radical is faster in ethanol aqueous solutions than in pure water or in ethanol alone, contributing to the high rate of H₂O₂ generation. Our technology provides new insights into sonochemistry and establishes a green synthetic system for H₂O₂ production.