Ultrahigh CO Research Articles

Development of Ultra–high CO<sub>2</sub> Permeable Separation Membranes Utilizing Nano–spaces and Their Deployment to DAC

Development of Ultra–high CO<sub>2</sub> Permeable Separation Membranes Utilizing Nano–spaces and Their Deployment to DAC

A reduced polyoxometalate-encapsulated organo cobalt modified phosphate framework for improving photocatalytic reduction of CO2.

A reduced polyoxometalate-based organo-metallophosphate (MOPO) framework formulated as [Co4(PO4)(C7H8N4)6](PWVI10WV2O40) (Co-PO4-PW12) with an ultra-high CO production rate of 13 676 μmol g-1 h-1 has been presented through photocatalytic CO2 reduction investigations.

Band Position-independent Piezo-electrocatalysis for Ultrahigh CO2 Conversion.

Piezo-electrocatalysis as an emerging mechano-to-chemistry energy conversion technique opens multiple innovative opportunities and draws great interest over the past decade. However, the two potential mechanisms in piezo-electrocatalysis, i.e., screening charge effect and energy band theory, generally coexist in the most piezoelectrics, making the essential mechanism remain controversial. Here, for the first time, we distinguish the two mechanisms in piezo-electrocatalytic CO2 reduction reaction (PECRR) through a narrow-bandgap piezo-electrocatalyst strategy using MoS2 nanoflakes as demo. With conduction band of -0.12eV, the MoS2 nanoflakes are unsatisfied for CO2 -to-CO redox potential of -0.53eV, yet they achieve an ultrahigh CO yield of ∼ 543.1 μmol·g-1 ·h-1 in PECRR. Potential band position shifts under vibration are still unsatisfied with CO2 -to-CO potential verified by a combination analysis of theoretical investigation and piezo-photocatalytic experiment, further indicating that the mechanism of piezo-electrocatalysis is independent of band position. Besides, MoS2 nanoflakes exhibit unexpected intense "breathing" effect under vibration and enable the naked-eye-visible inhalation of CO2 gas, independently achieving the complete carbon cycle chain from CO2 capture to conversion. The CO2 inhalation and conversion processes in PECRR are revealed by a self-designed in situ reaction cell. This work brings new insights into the essential mechanism and surface reaction evolution of piezo-electrocatalysis. This article is protected by copyright. All rights reserved.

Constructing atomic surface concaves on Bi5O7Br nanotube for efficient photocatalytic CO2 reduction

The development of advanced photocatalysts for CO2 reduction (CO2R) has attracted intensive interest but is severely plagued by the intrinsically narrow photo-responsive range, inefficient carrier separation of the current supports. Herein, the unconventional atomic surface concaves with Bi-O-Br complex vacancies on thin Bi5O7Br nanotubes were designed and successfully synthesized. This concave-rich structures provide electron localized enrichment regions that could address the above two issues simultaneously. The unique concaves serve as the active sites that enable the exceptional capacity for the capture and activation of CO2 and the formation of key intermediates. Ultimately, an ultrahigh CO yield rate of 30.96 μmol g−1 h−1 was obtained under ambient conditions without anchoring extra metal active species or any sacrificial agents. Our work not only provides a promising support but also proposes a unique structure to optimize the photocatalytic performance.

Constructing Bi2MoO6/Pomelo-Peel-Derived Carbon 0D/3D Heterojunctions To Enhance Photothermal Catalytic CO2 Reduction in Full Solar Spectrum

The carrier migration limitation has been a key factor restricting the photothermal catalytic CO2 reduction. To further enhance carrier transport, Bi2MoO6 quantum dots (BM QDs) are deposited on the surface of alkali-activated pomelo-peel-derived carbon (CPP-A) to construct CPP-A/BM QDs 0D/3D heterojunctions in this paper. BM QDs have extremely short carrier transport distances and achieve photothermal synergy through the graded utilization of the full solar spectrum. The carbon framework of CPP promotes the high dispersion of BM QDs (3 nm) and allows the local surface temperature of the catalyst to increase rapidly up to 100 °C. The critical role of heat enhances the diffusion, adsorption, and carrier migration processes of CO2 and provides the energy to cross the CO2 activation energy barrier. More importantly, the oxygen-containing groups of CPP and BM QDs form a C–O–Bi interfacial electron bridge, which provides a high-speed channel for carrier transport across the interface, allowing many electrons generated by BM QDs to migrate rapidly to the CPP surface, inducing CPP as a new electron-rich surface for rapid CO2 activation, which results in an ultrahigh CO yield of 61.44 μmol/(g·h) for CPP-A/BM QDs, and the catalytic activity is increased by 9.12 times.

Pyrrolic N anchored atomic Ni–N3–C catalyst for highly effective electroreduction of CO2 into CO

Herein, atomically dispersed Ni–N3–C materials are facilely synthesized by the pyrolysis of Ni-doped ZIF-8. Each single Ni atom is proved to be bonded with three N atoms to form Ni–N3 sites by X-ray absorption spectroscopy. During the pyrolysis at high temperature, the increasing of relative contents and blue-shift binding energy of pyrrolic N can be observed, indicating the Ni might be bonded with pyrrolic N. Moreover, the formation energy (Ef) of NiN3-pyrrolic structure is smaller than that of NiN3-pyridinic calculated by density functional theory (DFT), thus confirming the dominated bonding structure of NiN3-pyrrolic further. The optimum material can achieve an ultra-high CO Faradaic efficiency of 99.37% at −0.75 V vs. RHE with a turnover frequency (TOF) of 3498 h−1 and a high CO partial current density of 80 mA cm−2 at −1.15 V vs. RHE, which is among the best Ni catalysts. Based on DFT results, the NiN3-pyrrolic sites can facilitate both the formation of COOH* intermediate and desorption of CO, which can also suppress the competitive hydrogen evolution reaction (HER) simultaneously, thus resulting in high catalytic activity and selectivity from CO2 to CO.

Potassium-Assisted Fabrication of Intrinsic Defects in Porous Carbons for Electrocatalytic CO2 Reduction.

The fabrication of intrinsic carbon defects is usually tangled with doping effects, and the identification of their unique roles in catalysis remains a tough task. Herein, a K+ -assisted synthetic strategy is developed to afford porous carbon (K-defect-C) with abundant intrinsic defects and complete elimination of heteroatom via direct pyrolysis of K+ -confined metal-organic frameworks (MOFs). Positron-annihilation lifetime spectroscopy, X-ray absorption fine structure measurement, and scanning transmission electron microscopy jointly illustrate the existence of abundant 12-vacancy-type carbon defects (V12 ) in K-defect-C. Remarkably, the K-defect-C achieves ultrahigh CO Faradaic efficiency (99%) at -0.45V in CO2 electroreduction, far surpassing MOF-derived carbon without K+ etching. Theoretical calculations reveal that the V12 defects in K-defect-C favor CO2 adsorption and significantly accelerate the formation of the rate-determining COOH* intermediate, thereby promoting CO2 reduction. This work develops a novel strategy to generate intrinsic carbon defects and provides new insights into their critical role in catalysis.

Two-dimensional ionic liquids with an anomalous stepwise melting process and ultrahigh CO2 adsorption capacity

Ultrathin ionic liquid (IL) films have shown wide applications in the chemistry and materials fields. However, the structure feature and quantitative controlling mechanism of thin IL films have rarely been reported to date. Here, computational simulations combined with scanning tunnel microscope experiments are used to quantify the structure and function of the thinnest possible IL films, two-dimensional (2D) ILs, which consist of 2D ordered mono-ionic IL structures. Interestingly, the 2D ILs exhibit anomalous stepwise melting processes, involving localized rotated, out-of-plane flipped, and fully disordered states, which are different from 3D ILs. Meanwhile, a theoretical model and temperature-surface phase diagram are constructed to evaluate the critical stepwise melting behaviors. Furthermore, the 2D ILs also possess ultrahigh CO 2 adsorption capabilities and structural robustness during the CO 2 adsorption-desorption process. These findings are promising for the rational design of an IL-solid interface for CO 2 -capture-fixation chemistry and related applications. • 2D ionic liquid with ordered mono-ionic structure • The anomalous stepwise melting processes of 2D ionic liquids is revealed • A theoretical model is developed to evaluate the critical melting points • The 2D ionic liquids possess extremely high CO 2 adsorption capabilities Combining STM experiments and molecular dynamics simulations, Wang et al. investigate 2D ionic liquids that exhibit anomalous stepwise melting processes and superhigh CO 2 adsorption capacity. The 2D modification technique may provide a strategy for the precise control and function design of liquids.

Direct solar thermochemical CO2 splitting based on Ca- and Al- doped SmMnO3 perovskites: Ultrahigh CO yield within small temperature swing

Solar thermochemical CO2 splitting is a promising route to reduce environment pollution and mitigate energy crisis. However, traditional redox materials are limited by low CO production, slow reaction kinetics, and poor cycling stability, which results in low solar-to-fuel efficiency. Here, Ca- and Al- doped SmMnO3 perovskites are proposed for high-performance solar thermochemical CO2 splitting. The average CO yield of Sm0.6Ca0.4Mn0.8Al0.2O3 reaches a record-high value of 595.56 μmol g−1 when swinging between 1350 °C and 1100 °C. The CO yield is about 4.22 times as high as that of undoped SmMnO3 (140.97 μmol g−1) under the same conditions, and remains stable over multiple cycling. The ultrahigh CO yield can be attributed to the transformation of reaction mechanism from solid-state surface reaction (F2) to bulk diffusion model (D2). Besides, Ca- and Al- doped SmMnO3 perovskites possess high solar absorptance over 86.5% (in stark contrast to 12.1% of CeO2), so that only solar concentration ratio of 898 (Sm0.6Ca0.4Mn0.8Al0.2O3) is required to drive thermochemical reactions while benchmark CeO2 needs 1936. This work provides novel approaches for high-performance solar thermochemical CO2 splitting with high CO yield, good cycle stability, small temperature swing, and low solar concentration required.

Effective functionalization of porous polymer fillers to enhance CO2/N2 separation performance of mixed-matrix membranes

A series of porous organic polymers (denoted as PBP- x ) possessing various functional groups was synthesized via Friedel–Crafts alkylation followed by post-synthetic functionalization using amine and sulfonic groups. These functionalized porous polymers were incorporated into an in-house polyimide to fabricate mixed-matrix membranes for CO 2 /N 2 separation. Gas permeation testing revealed that these functionalized porous fillers substantially improved the CO 2 separation performance. Moreover, optimizing both the functionality and pore structure of the porous fillers was found to drastically improve the CO 2 /N 2 separation performance. In particular, the addition of 10 wt% PBP-menm (menm = 1,2-methylethylenediamine) induced an ultrahigh CO 2 permeability of 2988 barrers (158% higher than that of a pure polymer membrane), thus realizing excellent performance that surpasses the Robeson upper bound for CO 2 /N 2 separation. • Porous organic polymers possessing various functional groups were synthesized. • Defect-free mixed-matrix membranes comprising these functionalized porous fillers were successfully fabricated. • Optimizing both functionality and pore structure of porous fillers led to enhanced CO 2 transport. • The performance of the membrane with the optimum filler surpassed the Robeson upper bound for CO 2 /N 2 separation.

Engineering d-band center of nickel in nickel@nitrogen-doped carbon nanotubes array for electrochemical reduction of CO2 to CO and Zn-CO2 batteries

Self-supported transition-metal single-atom catalysts (SACs) facilitate the industrialization of electrochemical CO2 reduction, but suffer from high structural heterogeneity with limited catalytic selectivity. Here we present a facile and scalable approach for the synthesis of self-supported nickel@nitrogen-doped carbon nanotubes grown on carbon nanofiber membrane (Ni@NCNTs/CFM), where the Ni single atoms and nanoparticles (NPs) are anchored on the wall and inside of nitrogen-doped carbon nanotubes, respectively. The side effect of Ni NPs was further effectively inhibited by alloying Ni with Cu atoms to alter their d-band center, which is theoretically predicted and experimentally proved. The optimal catalyst Ni9Cu1@NCNTs/CFM exhibits an ultrahigh CO Faradic efficiency over 97% at −0.7 V versus reversible hydrogen electrode. Additionally, this catalyst shows excellent mechanical strength which can be directly used as a self-supporting catalyst for Zn-CO2 battery with a peak power density of ∼0.65 mW/cm2 at 2.25 mA/cm2 and a long-term stability for 150 cycles. This work opens up a general avenue to facilely prepare self-supported SACs with unitary single-atom site for CO2 utilization.

Plasmon-induced carrier separation boosts high-selective photocatalytic CO2 reduction on dagger-axe-like Cu@Co core–shell bimetal

Designing plasmonic catalysts capable of efficient and selective photocatalytic CO2 reduction is considerable important for future carbon energy utilization. Herein, among many plasmonic bimetals, dagger-axe-like [email protected] core–shell bimetal exhibits excellent photocatalytic CO2 reduction activity. The incorporation of Co layer into a Cu matrix constructs a core–shell structure, which could increase the CO2 adsorption capacity of Cu, thus promoting faster CO2 adsorption/activation. The electronic coupling of Co and Cu can also cause rapid interfacial charge-transfer dynamics. Therefore, the [email protected] sample exhibits enhanced catalytic activity for the reduction of CO2 to CO, and its CO production rate is 11043.33 µmol g−1 without photosensitizer and cocatalyst. Furthermore, [email protected] proved ultra-high CO selectivity (98%) and stability (48 h). This work offers a simple strategy to finely construct a fresh type of plasmonic photocatalyst for photocatalytic CO2 reduction.

Rational Fabrication of Low-Coordinate Single-Atom Ni Electrocatalysts by MOFs for Highly Selective CO2 Reduction.

Single-atom catalysts (SACs) have attracted tremendous interests due to their ultrahigh activity and selectivity. However, the rational control over coordination microenvironment of SACs remains a grand challenge. Herein, a post-synthetic metal substitution (PSMS) strategy has been developed to fabricate single-atom Ni catalysts with different N coordination numbers (denoted Ni-Nx -C) on pre-designed N-doped carbon derived from metal-organic frameworks. When served for CO2 electroreduction, the obtained Ni-N3 -C catalyst achieves CO Faradaic efficiency (FE) up to 95.6 %, much superior to that of Ni-N4 -C. Theoretical calculations reveal that the lower Ni coordination number in Ni-N3 -C can significantly enhance COOH* formation, thereby accelerating CO2 reduction. In addition, Ni-N3 -C shows excellent performance in Zn-CO2 battery with ultrahigh CO FE and excellent stability. This work opens up a new and general avenue to coordination microenvironment modulation (MEM) of SACs for CO2 utilization.

Rational Fabrication of Low‐Coordinate Single‐Atom Ni Electrocatalysts by MOFs for Highly Selective CO2 Reduction

AbstractSingle‐atom catalysts (SACs) have attracted tremendous interests due to their ultrahigh activity and selectivity. However, the rational control over coordination microenvironment of SACs remains a grand challenge. Herein, a post‐synthetic metal substitution (PSMS) strategy has been developed to fabricate single‐atom Ni catalysts with different N coordination numbers (denoted Ni‐Nx‐C) on pre‐designed N‐doped carbon derived from metal‐organic frameworks. When served for CO2 electroreduction, the obtained Ni‐N3‐C catalyst achieves CO Faradaic efficiency (FE) up to 95.6 %, much superior to that of Ni‐N4‐C. Theoretical calculations reveal that the lower Ni coordination number in Ni‐N3‐C can significantly enhance COOH* formation, thereby accelerating CO2 reduction. In addition, Ni‐N3‐C shows excellent performance in Zn–CO2 battery with ultrahigh CO FE and excellent stability. This work opens up a new and general avenue to coordination microenvironment modulation (MEM) of SACs for CO2 utilization.

Semimetal 1H‐SnS2 Enables High‐Efficiency Electroreduction of CO2 to CO

AbstractControlling the selectivity of products in CO2 fixation is essential to obtain desired products using phase engineering. In this study, stable semimetal 1H‐SnS2 nanosheets are successfully synthesized by hydrogen‐assisted low‐temperature calcination for the first time. Compared with semiconductor 1T‐SnS2, the 1H‐SnS2 exhibits ultrahigh CO selectivity with a Faradaic efficiency of 98.2% at −0.8 V (vs reversible hydrogen electrode) and a partial current density of 10.9 mA cm−2 in the electrocatalytic CO2 reduction reaction. Theoretical calculations indicate that the *COOH intermediate is more stable on 1H‐SnS2 surface than 1T‐SnS2 surface and thus promotes the CO production. This work shows that phase engineering control can be an effective approach to regulate the selectivity of products in CO2RR of transition metal dichalcogenides.

A Gyroidal MOF with Unprecedented Interpenetrating utc-c Network Exhibiting Exceptional Thermal Stability and Ultrahigh CO2 Affinity.

A zeolite-like gyroidal MOF (denoted as SCNU-1) constructed with Cu ions and 4-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)phenol has a featured interpenetrating uninodal utc-c network which is for the first time found in the real structure. Moreover, SCNU-1 exhibits high thermal (>773 K), solvent, and acid/base stabilities; the largest CO2 affinity, 90 kJ/mol, among the MOFs functionalized with an aromatic hydroxyl group; and excellent CO2/N2 selectivity.

Carbothermal activation synthesis of 3D porous g-C3N4/carbon nanosheets composite with superior performance for CO2 photoreduction

3D porous nanosheets composite comprised of graphitic carbon nitride (g-C3N4) and carbon was prepared by a simple pyrolysis and subsequent carbothermal activation method for the first time. The morphology and structural properties of obtained 3D porous g-C3N4/C nanosheets composite was systematically investigated. It was found that the morphology of the g-C3N4/C composite evolved from scroll-like structure to 3D porous nanosheets with ultrathin layer after 6 h activation, meanwhile, the specific surface area and pore volume were significantly increased. Such 3D porous nanosheets like these can function as effective catalysts for a range of gas-phase photocatalytic reactions such as photocatalytic reduction of CO2 with H2O vapor to produce value-added fuels. As a demonstration, outstanding photocatalytic activity was achieved on this 3D porous g-C3N4/C nanosheets composite, where ultra-high CO and CH4 yield of 229 and 112 μmol g−1-cat, respectively, were acquired under 7 h simulated solar irradiation, which were 25-fold better than that of bulk g-C3N4. The excellent photocatalytic performance should be attributed to the advantageous structural and compositional features.

Size‐Independent and Ultrahigh CO Gas Sensor Based on TiO2 Modified ZnO Tetrapods

ZnO tetrapods modified by TiO2 powder are synthesized using a simple fast thermal oxidation method, and theirs CO sensing properties are investigated. The ZnO tetrapods modified by TiO2 powder sensor is tested at 250–400 °C under different CO concentrations compared with pure ZnO tetrapods, ZnO nanoparticle, and ZnO powder sensors. With a good crystallinity and a high pore size, the ZnO tetrapods modified by TiO2 powder sensor shows the highest sensing response compared to other sensors, exhibiting a size‐independent property for CO. Additionally, the response time of ZnO tetrapods modified by TiO2 powder sensor is reduced. The improvement of the sensing properties is attributed to microstructure, lattice, surface area, and conductance modification of TiO2 additive together with a high diffusion process deeply inside the sensing layer through the large pore size.

Ultrahigh CO Sensing Capability of Au-Doped TiO2 Porous Nanoceramics

Ultrahigh CO Sensing Capability of Au-Doped TiO<SUB>2</SUB> Porous Nanoceramics

Ultrahigh CO 2 levels enhances cuphea growth and morphogenesis

Applications of ultrahigh CO 2 treatments accelerated cuphea ( Cuphea viscosissima × C. lanceolata ‘PSR23’) growth and development and aided in seedling establishment. The growth (fresh weight) and morphogenesis (number of leaves and roots and seedling length) were determined in cuphea seedlings exposed to 350, 1500, 3000, 10,000, or 30,000 μmol mol −1 CO 2 for 30 days under greenhouse conditions. Greater CO 2 levels, especially the ultrahigh levels (i.e. ≥3000 μmol mol −1 CO 2) resulted in significantly higher ( P ≤ 0.05) fresh weights, leaf numbers, root numbers, and seedling lengths compared to seedlings grown under ambient air (350 μmol mol −1 CO 2). For example, cuphea ‘PSR23’ Morris heavy seedlings showed the greatest seedling fresh weight, leaf number, root number, and seedling length when supplemented with 10,000 μmol mol −1 CO 2 increasing 607%, 184%, 784%, and 175%, respectively, when compared to seedlings grown without CO 2 enrichment.