CO Molecules Research Articles

Energy spectrum and magnetic susceptibility of the improved Pöschl-Teller potential

This study presents an analytical representation of the internal motion of a diatomic system using the improved Pöschl-Teller potential. The ro-vibrational energy spectrum is derived by solving the radial Schrödinger time independent wave equation (STIWE) under a 2D electromagnetic potential field. Additionally, an explicit equation for magnetic susceptibility is formulated from the internal partition function. The analytical models are used to investigate physical properties of CO (X1∑+), K2 (a3∑u+), BCl (X1∑+), and NaK (c3∑+) molecules. Average percentage absolute deviations (APAD) for the ro-vibrational energy spectrum are calculated as 0.1001 %, 0.5306 %, 1.2070 %, and 0.9779 %, respectively, compared to observed data. Numerical results are consistent with existing literature. Furthermore, the study reveals that the magnetic susceptibility of the system increases with temperature and decreases with an increase in magnetic field intensity, indicating its paramagnetic nature.

N-doped carbon confined ternary Pt2NiCo intermetallics for efficient oxygen reduction reaction

Developing high performance electrocatalysts for the cathodic oxygen reduction reaction (ORR) is essential for the widespread application of fuel cells. Herein, a promising Pt2NiCo atomic ordered ternary intermetallic compound with N-doped carbon layer coating (o-Pt2NiCo@NC) has been synthesized via a facile method and applied in acidic ORR. The confinement effect provided by the carbon layer not only inhibits the agglomeration and sintering of intermetallic nanoparticles during high temperature process but also provides adequate protection for the nanoparticles, mitigating the aggregation, detachment and poisoning of nanoparticles during the electrochemical process. As a result, the o-Pt2NiCo@NC demonstrates a mass activity (MA) and specific activity (SA) of 0.65 A/mgPt and 1.41 mA/cmPt2 in 0.1 mol/L HClO4, respectively. In addition, after 30,000 potential cycles from 0.6 V to 1.0 V, the MA of o-Pt2NiCo@NC shows much lower decrease than the disordered Pt2NiCo alloy and Pt/C. Even cycling at high potential cycles of 1.5 V for 10,000 cycles, the MA still retains ∼70%, demonstrating superior long-term durability. Furthermore, the o-Pt2NiCo@NC also exhibits strong tolerance to CO, SOx, and POx molecules in toxicity tolerance tests. The strategy in this work provides a novel insight for the development of ORR catalysts with high catalytic activity, durability and toxicity tolerance.

Boosting CO oxidation performance via reaction-induced single-atom active site: DFT and microkinetic investigation of a unified CO oxidation mechanism on Gd-doped ceria supported copper catalysts

Single-atom (SA) catalysts have emerged as a pivotal area drawing extensive research interest due to their high catalytic activities. However, SA catalysts are often plagued by the aggregation and deactivation of SA sites under reaction conditions. This study focuses on CO oxidation over Gd-doped ceria supported Cu catalysts and aims to provide a new strategy to stabilize the SA site, in which a Cu SA site is “prestored” in a relatively stable Cu cluster and can be dynamically activated under reaction conditions. Three typical Cu10/CeO2 catalyst models were built with different Gd-doping contents, which are pristine Cu10/CeO2, Cu10/Gd0.125Ce0.875O2, and Cu10/Gd0.25Ce0.75O2, respectively. We performed density functional theory (DFT) calculations on the Cu10/Gd-CeO2 system to investigate the adsorption of CO and O2 molecules, the formation of surface oxygen vacancy (OV) and dynamic Cu SA site, and potential energy surfaces of CO oxidation process. Ab initio thermodynamic analysis suggests that the saturation adsorption of CO on Cu10 and high Gd-doping in CeO2 lead to a spontaneously formed single Cu−CO site and an OV defect on ceria surface. The CO oxidation process is identified as a two-paths-coupled catalytic cycle, in which Path I is activated by the terminal O atom of adsorbed O2 at surface OV site while Path II initiates with the lattice O atom of CeO2 surface. The microkinetic modeling demonstrates that the dominant pathway is Path I for the undoped and low-doping cases, and Path II for the high-doping case which exhibits a novel mechanism for CO oxidation and the highest reaction activity due to the participation of the dynamic SA site.

Prediction of solubility of CO2, H2S, and their mixture in ionic liquids using the Cubic Two State equation of state

In this work, the capability of the Cubic Two State (CTS) equation of state (EoS) has been evaluated using the solubility of carbon dioxide (CO2), hydrogen sulfide (H2S), and their mixture in ionic liquids (ILs). The imidazolium-based ILs with [BF4], [PF6], and [Tf2N] anions have been studied. The self-association between IL molecules, CO2, and H2S molecules has been considered to optimize the pure model parameters. In addition to self-association between similar molecules, the cross-association between CO2-IL and H2S-IL in the binary mixtures has been considered. The results show that the CTS EoS can predict (kij=0.0) the solubility of H2S and CO2 in ILs ranging from 1 to 1000 bar satisfactory. The average ARD value for binary CO2-IL and H2S-IL systems has been obtained 20.3 % and 9.02, respectively. The CTS model has been used to predict the phase behavior of ternary systems containing CO2H2S-[C4mim][PF6], CO2H2S-[C8mim][PF6], and CO2H2S-[C8mim][Tf2N] at various temperatures. Finally, the CTS results have been compared to soft-SAFT and PC-SAFT EoSs. The results show that simple association contribution and the cubic term of the CTS EoS can model the molecular interactions between gases and ILs satisfactory. The CTS model can be considered as a robust and efficient thermodynamic model for the prediction of separation of CO2 and H2S using ILs.

Molecular insight into the dual effect of salts: Promoting or inhibiting the nucleation and growth of carbon dioxide clathrate hydrates

Facing the huge gap between the growing CO2 emissions and net-zero emissions target to mitigate global warming, the long-term storage of excess CO2 becomes an intractable issue. Sequestering CO2 in the oceans as clathrate hydrates is a promising solution. Many unanswered questions still exist at the molecular level regarding how ions in seawater kinetically affect the formation of CO2 hydrates, particularly the dual effect: as the concentration rises, salt ions shift from being a promoter of hydrate formation to becoming an inhibitor. Herein, we report the homogeneous nucleation process of CO2 hydrates in saline solutions via molecular dynamics simulations. Consistent with experimental findings, our results show that nucleation is promoted within certain salt concentration ranges; however, the evidence suggests that ions do not act as nucleation sites. Multiple ion-induced variations in the aqueous phase are analyzed, including changes in the mobility, structure, and CO2 solubility. We find that the presence of ions strengthens the hydrophobic interactions among the dissolved CO2 molecules, which are associated with the salting-out phenomenon, accounting for the promoting effect of salts at low concentrations. However, as the salt concentration increases, this advantage is offset, leading to the inhibiting effect at high salt concentrations. We demonstrate that anions are inevitably involved in the construction of the solid hydrate phase. Their presence disrupts the native tetrahedral connectivity of water molecules and imparts negative charges to the solid phase, thereby attracting cations. In addition to advancing our understanding of the intricate interactions among water, guest, and additive molecules to germinate ordered solid structures, these findings can accelerate the development and utilization of sustainable hydrate-based applications.

Boosting spatial and energy resolution in STM with a double-functionalized probe.

The scattering of superconducting pairs by magnetic impurities on a superconducting surface leads to pairs of sharp in-gap resonances known as Yu-Shiba-Rusinov (YSR) bound states. Similar to the interference of itinerant electrons scattered by defects in normal metals, these resonances reveal a periodic texture around the magnetic impurity. The wavelength of these resonances is, however, often too short to be resolved even by methods capable of atomic resolution, i.e., scanning tunneling microscopy (STM). We combine a CO molecule with a superconducting cluster pre-attached to an STM tip to maximize both spatial and energy resolution, thus demonstrating the superior properties of such double-functionalized probes by imaging the spatial distribution of YSR states. Our approach reveals rich interference patterns of the hybridized YSR states of two Fe atoms on Nb(110), previously inaccessible with conventional STM probes. This advancement extends the capabilities of STM techniques, providing insights into superconducting phenomena at the atomic scale.

Synergistic N-heterocyclic carbene and C2N integration for efficient and selective metal-free photocatalytic CO reduction to C2H5OH

In the pursuit of sustainable and highly efficient catalysts for the reduction of CO to valuable multi-carbon fuels, this study presents a novel metal-free catalyst, C/C2N, created by integrating N-heterocyclic carbene (NHC) into a C2N monolayer. Utilizing density functional theory, we demonstrate that this integration effectively addresses the individual limitations of C2N and NHC, neither of which can stably adsorb CO molecules on their own. The synergistic effect of C2N and NHC facilitates distinct CO adsorption energies on the C2N surface (−0.08 eV) and at the NHC site (−0.83 eV), leading to an exceptionally low C–C coupling energy barrier of 0.41 eV, surpassing traditional metal-based catalysts. Computational results reveal that C/C2N exhibits outstanding activity and selectivity in reducing CO to C2H5OH, with a remarkably low free energy barrier of only 0.34 eV, further reducible to 0.20 eV under alkaline conditions. Furthermore, the integration of NHC into the C2N monolayer markedly narrows its band gap, enhancing visible light absorption and optimizing band edge positions, suggesting its potential for visible-light-driven reactions. Our findings establish C/C2N as an effective and selective metal-free photocatalyst with a notably low C–C coupling energy barrier, offering a novel avenue for CO conversion to multi-carbon fuels.

Dry Reforming of Methane to Syngas Mediated by Rhodium-Cobalt Oxide Cluster Anions Rh2CoO.

Dry reforming of methane (DRM) to syngas is an important route to co-convert CH4 and CO2. However, the highly endothermic nature of DRM induces the thermocatalysis to commonly operate at high temperatures that inevitably causes coke deposition through pyrolysis of methane. Herein, benefiting from the mass spectrometric experiments complemented with quantum chemical calculations, we have discovered that the bimetallic oxide cluster Rh2CoO- can mediate the co-conversion of CH4 and CO2 at room temperature giving rise to two free H2 molecules and two adsorbed CO molecules (COads). The only elementary step requiring the input of external energy (e.g., high temperature) is desorption of COads from the reaction intermediate Rh2CoOC2O2-. The doping effect of Co has also been clarified that the Co could tune the charge distribution and orbital energy of the active metal Rh, enabling the enhancement of cluster reactivity toward C-H activation, which is essential to facilitating the DRM to syngas. This work not only underlines the importance of temperature control over elementary steps in practical thermocatalysis but also identifies a promising active species containing the late 3d transition metal to drive DRM to syngas. The findings could provide novel insights into design of bimetallic catalysts for co-conversion of CH4 and CO2 at low temperatures.

Investigating the Structure of Defects in Heterometallic Zeolitic Imidazolate Frameworks ZIF-8(Zn/Cd) and Its Interaction with CO2 Using First-Principle Calculations

Inducing defect in metal-organic frameworks (MOFs) is one of the strategies to modify the structure and properties of this functional material. Defect may occur in a pristine MOF due to missing organic linkers, metal centres and/or other structural behaviours. In this study, the structure of defects in multicomponent MOFs especially heterometallic MOFs of zeolitic imidazolate framework (ZIF-8(Zn/Cd)) was examined to unveil the possible preference defect formation due to missing 2-methylimidazolate (MeIm) and metal centres of Cd2+ and Zn2+. Assuming defect formation due to the reaction between ZIF-8(Zn/Cd) and water, MeIm linker removal is energetically lower than removing metal centres of either Cd2+ or Zn2+. But, the MeIm linker is easier to be removed when it is connected to Cd2+ (Cd-MeIm-Cd) than when it is connected to Zn2+ (Zn-MeIm-Zn). Defect in ZIF-8(Zn/Cd) affects the band gap energy to give slightly lower value than it in pristine ZIF-8(Zn/Cd). Non-covalent interaction (NCI) and interaction region indicator (IRI) analyses were also performed to indicate possible intermolecular forces such as van der Waals and attractive forces present in non-defective and defective ZIF-8(Zn/Cd). The presence of defects in mixed-metal ZIF-8(Zn/Cd) was also tested for its potential use on CO2 adsorption. The interaction energy of CO2 inside defective ZIF-8(Zn/Cd) indicates an exothermic behaviour where CO2 molecule has a preference to be adsorbed inside the framework. This is especially when the capping agents at the defective ZIF-8(Zn/Cd) sites are removed to give open metal sites. This study provides insight how defects in multicomponent MOFs might presence affecting the structural and properties changes. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

CO2 adsorption on 3d transition metal-alloyed Pt clusters supported on pyridinic N-doped graphene

CO2 adsorption on Pt4 and on Pt2M2 (M = Co, Ni, and Cu) clusters supported on N-doped graphene (PNG) was analyzed using density functional theory. The Pt2M2 (M = Co, Ni) clusters supported on PNG had the maximum binding energy and charge transfer. Furthermore, the adsorption energy and charge transfer of CO2 were high for Pt2M2 (M = Co, Ni, and Cu) supported on PNG. In addition, bond elongation and bending angle were observed in the CO2 molecule after it was adsorbed on metal clusters supported on PNG. Non-covalent interaction contours revealed a repulsive interaction due to the steric effect between Pt2M2 (M = Co, Ni, and Cu) and PNG, whereas the Pt4/PNG composite showed a combination of repulsive and van der Waals interactions. This investigation proved that Pt2M2 (M = Co, Ni, and Cu) clusters supported on PNG are promising candidates for CO2 adsorption and activation.

Preparation of MoS2/V2O5 nanocomposites for ciprofloxacin degradation and Cr (VI) reduction

In this study, MoS2/V2O5 nanocomposites are obtained by hydrothermal process, and used for photocatalytic system of Ciprofloxacin (CIP) degradation and Cr (VI) reduction. Owing to its novel characteristics, MoS2/V2O5 heterojunctions are revealed as potential semiconductors in this region. V2O5 photocatalyst acts as a charge acceptor, meantime MoS2 acts as an electron donor, therefore promoting charge carrier separation and enhancing photocatalytic efficiency. The MoS2/V2O5 nanocomposites displayed enhanced photocatalytic CIP (98.7 %) and Cr (VI) reduction (98.8 %) after 120 min and 100 min of visible light activity. In contrast, in the first cycle, the photocatalysis capability of the photocatalyst performed in six cycles is 93.8 %. The Kapp values of MoS2/ V2O5 nanocomposites displayed about 11.2 and 19.5-times improvement of photocatalytic of CIP degradation and Cr (VI) reduction, respectively. The MoS2/V2O5 nanocomposites exhibited an enhanced photocurrent density of 0.082 μA/cm−2 compared to a pristine MoS2 sample of 0.045 μA/cm−2. The distinguished heterojunction photocatalysis performance is due to the significant migration of interfacial charges and the inhibited recombination rate of electron-hole pairs. CIP Pollutants eventually decay into H2O, CO2, and small molecule intermediates by generating •O2-, •OH, and h+. The influences of reactive radicals follow the order of •O2- radicals > h+ radicals > •OH radicals. Then, the probable structures of intermediates and achievable photodegradation pathways were discussed for the removal of CIP and Cr (VI) reduction using nanocomposite with visible light response.

Investigating the microscopic enhancement mechanisms of adsorption-based CO2 capture with Cu-loaded γ−Al2O3 using density functional theory

Transition-metal-loaded γ−alumina (Al2O3) is considered to be an effective adsorbent for CO2 capture, but its microscopic process and mechanisms of CO2 adsorption are not fully understood. To investigate the microscopic enhancement role of Cu atoms in CO2 adsorption, this work compares various adsorption configurations and parameters of CO2 on γ−Al2O3 (110) facets with or without Cu atoms and small Cu cluster loading (Cun (n=1,2,3)/γ−Al2O3) using the first-principles approach. According to the adsorption energy, charge transfer, difference charge density, and other parameters of different configurations, the γ−Al2O3 (110) slab loaded with the Cu atom is found to exhibit enhanced adsorption of CO2 molecules compared to that without Cu loading. Moreover, the surface stability increases with the number of loaded Cu atoms. However, the hydroxyl groups in the active sites partially undermine the adsorption effect during the CO2 adsorption process. The density of states indicates that the doping of Cu atoms in the system creates an orbital peak closer to the Fermi energy level. This facilitates the transfer of charge within the slab, making the activation of CO2 easier and promoting stable adsorption. Finally, the amount of crystal orbital overlap population and crystal orbital Hamilton population shows that the stability of adsorption is due to the formation of C-Cu and C-Al bonds. It is demonstrated that the Cun-loaded γ−Al2O3 (110) slab improves the adsorption performance and contributes to a better understanding of the effect of transition-state metal loaded γ−Al2O3 on CO2 adsorption.

Role of H2O Adsorption in CO Oxidation over Cerium-Oxide Cluster Anions (CeO2)nO- (n = 1-4).

Water (H2O) is ubiquitous in the environment and inevitably participates in many surface reactions, including CO oxidation. Acquiring a fundamental understanding of the roles of H2O molecules in CO oxidation poses a challenging but pivotal task in real-life catalysis. Herein, benefiting from state-of-the-art mass-spectrometric experiments and quantum chemical calculations, we identified that the dissociation of a H2O molecule on each of the cerium oxide cluster anions (CeO2)nO- (n = 1-4) at room temperature can create a new atomic oxygen radical (O•-) that then oxidizes a CO molecule. The size-dependent reactivity of H2O-mediated CO oxidation on (CeO2)nO- clusters was rationalized by the orbital compositions (O2p) and energies of the lowest unoccupied molecular orbitals of active O•- radicals modified by H2O dissociation. Our findings not only provide new insights into H2O-mediated CO oxidation but also demonstrate the importance of H2O in modulating the reactivity of the O•- radicals.

Synthesis of metal-doped covalent triazine frameworks: Incorporation into 6FDA-Durene polyimide for CO2 separation through mixed matrix membranes

The development of advanced mixed matrix membranes (MMMs) is expanding through the design of functionalized materials and efficient hybrid mass transfer mechanisms to meet the growing needs for practical and cost-effective gas separation technologies. Here, a novel series of transition metal-doped covalent triazine frameworks (M2+CTFs) was synthesized and incorporated into a 6FDA-Durene polyimide (PI) matrix in the range of 0–0.5 wt% to prepare cost-effective facilitated transport MMMs with high CO2 separation performance. Qualitative and quantitative analyses including FTIR, XPS, CHN, XRF, BET, XRD, TGA, DLS, FESEM, EDX, and TEM were carried out. The presence of nucleophilic N sites and electron-rich heterocycles in highly porous CTFs (through the π–π-stacking interactions with CO2 molecules), together with transition metal ions (Fe2+, Cu2+, and Zn2+) as the fixed site active carriers (with strong CO2 facilitated transport through the π complexation/decomplexation reaction), improves the affinity for CO2 molecules, facilitates their transport, and subsequently increases the CO2/non-polar gas selectivity of MMMs. The resultant M2+CTF/PI MMMs successfully surpass the 2008 upper bound at filler loading of 0.4 wt% for CO2/CH4 and CO2/N2 separations. Embedding M2+CTFs into the PI matrix improves the mechanical properties of the membranes. The Zn2+CTF/PI MMM represents the best separation performance with a CO2 permeability of 1408 Barrer, a CO2/N2 selectivity of 37, and a CO2/CH4 selectivity of 39, which represents a 120 %, 111 %, and 110 % increase compared to the neat PI membrane at a feed pressure of 2 bar. The excellent results of the present study indicate the high potential of cost-efficient synthesized M2+CTF particles and related facilitated transport MMMs for possible application in industrial processes.

Theoretical study of tandem catalysts based on metal porphyrin-phthalocyanine two-dimensional carbon-rich conjugated frameworks for the co-reduction of NO3− and CO2 in the electrosynthesis of methylamine

Electrocatalytic NO3− and CO2 co-reduction to synthesize methylamine can remove NO3− and CO2 pollutants and produce valuable methylamine. However, the catalytic mechanism of electrocatalytic NO3− and CO2 co-reduction for the synthesis of methylamine is not sufficiently understood, and this research remains challenging. To supply the catalytic mechanism needed to create effective electrocatalysts, we systematically investigated the performance of metal-extended phthalocyanine and metalloporphyrin tandem catalysts to produce methylamine electrocatalytically through the co-reduction of NO3− and CO2 and found that the MoCo-Pc-Pt-N5Por COFs, MoNi-Pc-Pt-N5Por COFs, and MoRu-Pc-Pt-N5Por COFs were the most effective electrocatalysts. Also, we found that the metallic TM atoms in the catalysts with the NO3− and CO2 molecules with the coexistence of charge depletion and charge accumulation behavior as the activation mechanism of NO3− and CO2. This work offers a theoretical foundation for experimental research and opens up new possibilities for the rational design of effective electrocatalytic NO3− and CO2 co-reduction catalysts for synthesizing methylamine.

Structure and Dynamics of Carbon Dioxide inside ”Hot” Ice with Cylindrical Channels

Inclusion compound based on crystalline water is increasingly recognized as a promising solution for carbon dioxide (CO2) capture, either for carbon sequestration from greenhouse gas emissions or for gas mixture separation. Molecular dynamics simulations revealed that water crystallizes into a novel porous structure in a carbon nanobrush environment even at room temperature, thus termed ”hot” ice whose structure code is dtc. This study employs a hybrid Grand Canonical/isothermal-isobaric Monte Carlo (GCMC) simulations to investigate CO2 confinement inside the cylindrical channels of ice dtc structure. The results show that CO2 occupancy, here expressed as CO2-to-water mole ratio, is approximately 2:5 at maximum. The simulations also demonstrate the mechanical stability of ice dtc structure under positive pressures when its voids are filled with CO2. Furthermore, molecular dynamics simulations are performed to provide molecular insights into the structures and dynamics of CO2 inside the porous channels framework. The results show that CO2 molecules form a bilayer structure inside the cylindrical channels, where certain molecule orientation angles are favored. Dynamics analysis shows that CO2 molecules are relatively immobile in all directions at maximum occupancy.

Structural stability and adsorption behaviour of CO2-loaded pure silica CHA and ITW zeolites upon compression

The present study investigates the structural stability and adsorption behavior of ultrahigh CO2-loaded pure-silica zeolites chabazite (CHA) and ITQ-12 (ITW) under high pressure conditions. To analyze these properties, we have utilized in situ synchrotron-based X-ray powder diffraction techniques. Lattice indexation provides information of the filling process and, through Rietveld refinements and Fourier recycling methods, we have been able to (i) determine the location and amount of guest carbon dioxide molecules within the cavities of pure-SiO2 CHA zeolite and (ii) tentatively determine that within the channels of the porous pure-SiO2 ITW framework. The filling of the zeolite pores with CO2 molecules was found to have a positive impact on the structural stability of both CHA and ITW under compression, which do not undergo pressure-induced amorphization up to 12.2 GPa and 15.9 GPa, respectively. Interestingly, low compressibility takes place in CHA zeolite below 4 GPa during CO2 loading and a second-order phase transition occurs in CO2-filled ITW zeolite at 2.1 GPa. These results highlight the influence of CO2 adsorption on the compressibility behavior of these zeolites. Overall, our study provides detailed insights into the structural behavior of CO2-loaded CHA and ITW under high pressure and allows comparison with other pure silica zeolites described in the literature.

Hydrate Technologies for CO2 Capture and Sequestration: Status and Perspectives.

CO2 capture and sequestration based on hydrate technology are considered supplementary approaches for reducing carbon emissions and mitigating the greenhouse effect. Direct CO2 hydrate formation and CH4 gas substitution in natural gas hydrates are two of the main methods used for the sequestration of CO2 in hydrates. In this Review, we introduce the crystal structures of CO2 hydrates and CO2-mixed gas hydrates and summarize the interactions between the CO2 molecules and clathrate hydrate/H2O frames. In particular, we focus on the role of diffraction techniques in analyzing hydrate structures. The kinetic and thermodynamic properties then are introduced from micro/macro perspectives. Furthermore, the replacement of natural gas with CO2/CO2-mixed gas is discussed comprehensively in terms of intermolecular interactions, influencing factors, and displacement efficiency. Based on the analysis of related costs, risks, and policies, the economics of CO2 capture and sequestration based on hydrate technology are explained. Moreover, the difficulties and challenges at this stage and the directions for future research are described. Finally, we investigate the status of recent research related to CO2 capture and sequestration based on hydrate technology, revealing its importance in carbon emission reduction.

Unveiling the Obscure Potential of O-Carborane Based IFLPs for CO2 Sequestration.

Sequestering carbon dioxide (CO2) from the atmosphere is necessary to achieve a sustainable environment. However, the thermodynamic stability of the CO2 molecule poses a significant challenge to its capture, necessitating catalysts that can overcome this stability. The emergence of frustrated Lewis pairs (FLPs) has opened a new dimension in the development of organocatalysts for CO2 capture and utilization. To date, various FLPs have been developed for CO2 sequestration, yet the quest for robust FLPs continues. Based on the intriguing electronic effects of the carborane polyhedral, o-carboranes can be projected as a versatile bridging unit for intramolecular FLPs (IFLPs). In the present work, o-carborane based IFLPs i. e., 1-Al(CH3)2-2-P(CH3)2-1,2-C2B10H10, 1-B(CH3)2-2-P(CH3)2-1,2-C2B10H10, 1-Al(CH3)2-2-N(CH3)2-1,2-C2B10H10, 1-P(CH3)2-2-B(CH3)2-1,2-C2B10H10 abbreviated as AlP, BP, AlN and BN have been proposed for the activation of CO2 molecule. The density functional theory (DFT) based calculations and thorough orbital analysis have been carried out to extensively study the electronic structure of the o-carborane unit. The proposed IFLPs were systematically compared with their corresponding phenyl bridged analogues to assess the effect of o-carborane bridging unit on the reactivity of the acidic and basic sites. The results show that the o-carborane supported IFLPs are more reactive towards CO2 than the phenyl bridged IFLPs. Also, placing the basic site on the B atom at the 4th position of the o-carborane bridge rather than the C atom at the 2nd position results in more reactive IFLPs.

Photocatalytic CO2 Reduction to Ethanol by ZnCo2O4/ZnO Janus Hollow Nanofibers.

Photocatalytic carbon dioxide (CO2) reduction for high-value hydrocarbon fuel production is a promising strategy to tackle global energy demand and climate change. However, this technology faces formidable challenges, primarily stemming from low yield and poor selectivity of C2 products of the desired hydrocarbon fuels. This study reported ZnO/ZnCo2O4 Janus hollow nanofibers (ZnO/ZCO JHNFs) prepared by electrospinning and atomic layer deposition. Photocatalytic tests revealed an ethanol yield of 4.99 μmol g-1 h-1 for ZnO/ZnCo2O4 JHNFs, surpassing mixed ZnO/ZnCo2O4 nanofibers (ZnO/ZCO NFs) by 4.35 times and pure ZnO by 12.7 times. The selectivity of 58.8% is 2.38 and 4.49 times higher than those of ZnO/ZnCo2O4 NFs and ZnO, respectively. These enhancements are attributed to efficient carrier separation facilitated by the ordered internal electric field of the Z-scheme heterojunction interface, validated by the energy band evaluations from experimentation and density functional theory (DFT) simulations and charge separation characterizations of photocurrent, impedance, and photoluminescence spectra. The Janus structure also effectively exposes the surface of ZnCo2O4 to CO2 molecules, increasing the active site availability, as confirmed by BET nitrogen adsorption/desorption, temperature-programmed desorption tests, and DFT adsorption energy calculations. This study proposes a novel approach for efficient photocatalytic hydrocarbon fuel production, with potential applications in energy and climate crisis mitigation.