CO Adsorption Sites Research Articles

New insight into photocatalytic CO2 conversion with nearly 100% CO selectivity by CuO-Pd/HxMoO3−y hybrids

Photocatalytic CO2 reduction holds promise for solving climate change. However, low conversion efficiency and low product selectivity limit current systems. Here, we report a strategy involving CuO-Pd deposited on HxMoO3−y with abundant oxygen vacancies (OVs) that drives CO2 photocatalytic reduction toward CO with nearly 100% selectivity and apparent quantum efficiency of 3.0% at 650 nm in H2O vapor at 100 °C. Detailed characterizations demonstrate that high performance mainly stems from the synergistic effect of the paired Cu-Pd sites in CuO-Pd and OVs in HxMoO3−y, where OVs serve as CO2 adsorption sites and induce the migration of localized electrons across the Schottky barrier to Cu-Pd sites, and then Cu-Pd sites promote CO2 reduction to CO. Theoretical calculation shows the strong hybridizations of Cu 3d - and Pd 3d - O 2p orbitals accelerate electrons transfer from CuO-Pd to CO2, effectively optimizing the rate-limiting step (CO2 * → COOH*).

The Study of MgO and/or ZrO2 Modified Al2O3 for CO2 Adsorption

Alumina (Al2O3) is widely used as a sorbent in CO2 adsorption and as a catalyst support in CO2 utilization. For this application, the CO2 adsorption ability is the most important property to be improved. Thus, this work presents the idea to modify the surface of a commercial alumina using an Mg-Zr mixed oxide. With this material, sites for CO2 adsorption can be created by generating oxygen mobility property simultaneously with the basicity. To prove this hypothesis, alumina modified with MgO, ZrO2, or Mg-Zr mixed oxide was prepared by an incipient wetness impregnation. The physicochemical properties of the bare alumina and the alumina modified with MgO, ZrO2, or Mg-Zr mixed oxide were investigated using N2 adsorption-desorption and X-ray diffraction. The achievement of oxygen mobility creation was quantitatively evaluated by O2-temperature programmed desorption measurement. The CO2 adsorption performance with the distribution of basic site strength was determined by CO2-temperature programmed desorption measurements. According to the results, the highest oxygen mobility was found in the alumina modified with Mg-Zr mixed oxide, which is approximately 1.7 times that of the bare alumina. The alumina modified with Mg-Zr mixed oxide showed the highest CO2 capacity by approximately 1.4 times compared to the alumina. It is because the cubic ZrO2 stabilized with MgO provided the number of oxygen vacancy sites that can be filled by oxygen atoms in adsorbed CO2 corresponding to the moderate and strong basic sites.

CO2 capture from wet flue gas using transition metal inserted porphyrin-based metal-organic frameworks as efficient adsorbents

CO2 capture from large point sources is indispensable for achieving 1.5 degree target as long as fossil fuels are still in use. Selective adsorption of CO2 from flue gas constitutes a promising CO2 capture technology, thanks to the development of numerous fascinating solid adsorbents in the past three decades. However, very few adsorbents can retain their required performance in the presence of moisture which is unfortunately always the case in reality. In this study, we elevated the CO2 adsorption and separation performance of a water-stable aluminum-based porphyrin metal-organic frameworks (Al-PMOF) by inserting transition metals as adsorption sites. Compared with the pristine Al-PMOF and other four transition metals (TMs) incorporated PMOFs (Al-PMOF(M)), the Co-inserted Al-PMOF (Al-PMOF(Co)) exhibited the highest CO2 adsorption capacity (3.32 mmol/g) and highest CO2/N2 and CO2/CH4 selectivity (87 and 20, respectively) at 273 K and 1.0 bar. After three consecutive cyclic moisture treatments, the CO2 adsorption capacity of Al-PMOF(Co) remained almost unchanged. More importantly, the dynamic binary CO2/N2 breakthrough adsorption of Al-PMOF(Co) exhibited negligible differences in CO2 adsorption capacities between dry and wet flue gas conditions, suggesting that TMs incorporated Al-PMOF possess excellent moisture-resistant properties. Mechanistic studies using the combined in situ synchrotron infrared spectroscopic and powder X-ray diffraction together with density functional theory calculations unambiguously revealed the inserted metals are the dominant CO2 adsorption sites. This study materializes the rational design of efficient adsorbents for CO2 capture and contributes to mitigating climate change.

Increased CO2 Affinity and Adsorption Selectivity in MOF-801 Fluorinated Analogues.

The novel ZrIV-based perfluorinated metal–organic framework (PF-MOF) [Zr6O4(OH)4(TFS)6] (ZrTFS) was prepared under solvent-free conditions using the commercially available tetrafluorosuccinic acid (H2TFS) as a bridging ditopic linker. Since H2TFS can be seen as the fully aliphatic and perfluorinated C4 analogue of fumaric acid, ZrTFS was found to be isoreticular to zirconium fumarate (MOF-801). The structure of ZrTFS was solved and refined from X-ray powder diffraction data. Despite this analogy, the gas adsorption capacity of ZrTFS is much lower than that of MOF-801; in the former, the presence of bulky fluorine atoms causes a considerable window size reduction. To have PF-MOFs with more accessible porosity, postsynthetic exchange (PSE) reactions on (defective) MOF-801 suspended in H2TFS aqueous solutions were carried out. Despite the different H2TFS concentrations used in the PSE process, the exchanges yielded two mixed-linker materials of similar minimal formulae [Zr6O4(μ3-OH)4(μ1-OH)2.08(H2O)2.08(FUM)4.04(HTFS)1.84] (PF-MOF1) and [Zr6O4(μ3-OH)4(μ1-OH)1.83(H2O)1.83(FUM)4.04(HTFS)2.09] (PF-MOF2) (FUM2– = fumarate), where the perfluorinated linker was found to fully replace the capping acetate in the defective sites of pristine MOF-801. CO2 and N2 adsorption isotherms collected on all samples reveal that both CO2 thermodynamic affinity (isosteric heat of adsorption at zero coverage, Qst) and CO2/N2 adsorption selectivity increase with the amount of incorporated TFS2–, reaching the maximum values of 30 kJ mol–1 and 41 (IAST), respectively, in PF-MOF2. This confirms the beneficial effect coming from the introduction of fluorinated linkers in MOFs on their CO2 adsorption ability. Finally, solid-state density functional theory calculations were carried out to cast light on the structural features and on the thermodynamics of CO2 adsorption in MOF-801 and ZrTFS. Due to the difficulties in modeling a defective MOF, an intermediate structure containing both linkers in the framework was also designed. In this structure, the preferential CO2 adsorption site is the tetrahedral pore in the “UiO-66-like” structure. The extra energy stabilization stems from a hydrogen bond interaction between CO2 and a hydroxyl group on the inorganic cluster.

Visible-light-driven CO2 reduction and H2 evolution boosted by 1D Cu2O/CuO heterostructures

The CO2 reduction reaction (CO2RR) offers an efficient path to the neutral carbon cycle and clean energy storage. For this reaction, 1D copper oxides (CuxO) are promising photocatalyst since promote an efficient charge transfer, suppress the photocorrosion, and provide active sites for CO2 adsorption. Therefore, in this work, 1D Cu2O/CuO heterostructures were manufactured by thermal oxidation of a copper mesh. This method works at atmospheric pressure, it is scalable, and it has a high yield, in a view of large-scale production. The copper mesh, a 3D metal skeleton, was selected as the substrate due to good light diffusion, low cost, and easy application. The characterization carried out made it possible to identify a homogeneous growth of the 1D Cu2O/CuO nanoneedles, which presented adequate band gaps for their activation with visible light and a stable photocurrent. These properties favored the CO2RR to solar fuels: HCOOH, CH3OH, HCOH, CH4, and CH3CH2OH. Furthermore, the samples exhibited activity for H2 evolution from H2O splitting. In this reaction, the heterostructures suffer photocorrosion of CuO to Cu2O, which competes for the electrons photogenerated during the reaction. However, this phenomenon was effectively suppressed by the addition of the CO2RR products and seawater as sacrificial agents. In general, the productions obtained from both reactions were up to 45% higher than the reference, which was attributed to the efficient transport of charges in the 1D architectures, the affinity for CO2, and its homogeneous exposure.

GeFSIX‐1‐Cu based semi‐interpenetrating network mixed matrix membranes for efficient CO2 separation

AbstractIn order to increase CO2 separation efficiency, semi‐interpenetrating network mixed matrix membranes (SIPN‐MMMs) were loaded with GeFSIX‐1‐Cu (Cu(4,4′‐bipyridine)2(GeF6)) and poly ethylene glycol dimethyl ether (PEGDME). Two long‐chain polymers poly ethylene glycol diacrylate (PEGDA) and poly ethylene glycol methyl ether acrylate (PEGMEA) jointly constituted a crosslinked PEO backbone, and CO2‐philic short‐chain polymer PEGDME and anion‐pillared hybrid porous materials GeFSIX‐1‐Cu were embedded into the backbone to introduce strong CO2 adsorption sites and provide extra pore channels. Increasing GeFSIX‐1‐Cu loading in SIPN‐MMMs initially improved CO2 permeability and CO2/N2, CO2/CH4, and CO2/H2 selectivity, because the porous structure of GeFSIX‐1‐Cu provides additional pore channels for gas transport. In addition, the strong binding affinity between GeF62− and CO2 leads to improved membrane selectivity. When GeFSIX‐1‐Cu loading increased above 3 wt%, both CO2 permeability and CO2/N2, CO2/CH4, and CO2/H2 selectivity decreased, due to agglomeration of excess GeFSIX‐1‐Cu loading in SIPN‐MMMs. The highest CO2 permeability of 786 Barrer and CO2/N2 ideal selectivity of 43 (at GeFSIX‐1‐Cu loading of 3 wt%) were 36% and 38% higher than those of pure SIPN membrane, respectively, resolving the trade‐off between permeability and selectivity, and surpassing the Robeson upper bound (2008).

Nitrogen doping of indium oxide for enhanced photocatalytic reduction of CO2 to methanol

Herein, the nitrogen-doped indium oxide (N-In2O3) photocatalyst was confirmed to be highly active and stable for photocatalytic reduction of CO2 to methanol in an aqueous solution at ambient conditions. The efficiency of N-In2O3 in producing methanol can be flexibly improved by tuning the nitrogen doping content. The highest formation rate of methanol reaches to 394 μmol gcat-1 h-1, with a methanol selectivity of 63%, at a nitrogen doping content of 3.74%. Nitrogen doping generates mid-gap energy states and reduces the bandgap of In2O3, thus boosting photon absorption and electron-hole separation. Nitrogen doping creates more oxygen vacancies on In2O3, thus forming more active sites for CO2 adsorption and conversion. Nitrogen doping also enhances the activity of the surface frustrated Lewis pairs (SFLPs), which further promotes CO2 adsorption and activation. The multiple-role of nitrogen doping results in the highly active and stable photocatalytic reduction of CO2 to methanol.

Ru/HxMoO3-y with plasmonic effect for boosting photothermal catalytic CO2 methanation

Utilizing localized surface plasmon resonance (LSPR) effect of catalysts to facilitate photothermal catalysis of CO2 to CH4 is an attractive strategy for mitigating CO2 emissions. Herein, we demonstrate that Ru/HxMoO3-y synthesized via H-spillover exhibits plasmonic absorption in the visible-near-infrared (Vis-NIR) region, achieving a CH4 yield of 20.8 mmol/gcat/h (520 mmol/gRu/h) with 100 % selectivity in the CO2 methanation under Vis-NIR light irradiation at 140 °C. Irradiation with Vis-NIR light substantialy increases the CH4 yield (~ 4.7 fold) compared with that under dark conditions. The abundant surface oxygen vacancies provide active sites for CO2 adsorption and activation. In situ infrared spectroscopic analysis reveals that photothermal catalytic CO2 methanation follows *CO pathway. This work represents a simple strategy for developing a plasmonic catalyst for efficient photothermal catalytic CO2 methanation.

Decoupling the Chemical and Mechanical Strain Effect on Steering the CO2 Activation over CeO2-Based Oxides: An Experimental and DFT Approach.

Doped ceria-based metal oxides are widely used as supports and stand-alone catalysts in reactions where CO2 is involved. Thus, it is important to understand how to tailor their CO2 adsorption behavior. In this work, steering the CO2 activation behavior of Ce–La–Cu–O ternary oxide surfaces through the combined effect of chemical and mechanical strain was thoroughly examined using both experimental and ab initio modeling approaches. Doping with aliovalent metal cations (La3+ or La3+/Cu2+) and post-synthetic ball milling were considered as the origin of the chemical and mechanical strain of CeO2, respectively. Experimentally, microwave-assisted reflux-prepared Ce–La–Cu–O ternary oxides were imposed into mechanical forces to tune the structure, redox ability, defects, and CO2 surface adsorption properties; the latter were used as key descriptors. The purpose was to decouple the combined effect of the chemical strain (εC) and mechanical strain (εM) on the modification of the Ce–La–Cu–O surface reactivity toward CO2 activation. During the ab initio calculations, the stability (energy of formation, EOvf) of different configurations of oxygen vacant sites (Ov) was assessed under biaxial tensile strain (ε > 0) and compressive strain (ε < 0), whereas the CO2-philicity of the surface was assessed at different levels of the imposed mechanical strain. The EOvf values were found to decrease with increasing tensile strain. The Ce–La–Cu–O(111) surface exhibited the lowest EOvf values for the single subsurface sites, implying that Ov may occur spontaneously upon Cu addition. The mobility of the surface and bulk oxygen anions in the lattice contributing to the Ov population was measured using 16O/18O transient isothermal isotopic exchange experiments; the maximum in the dynamic rate of 16O18O formation, Rmax(16O18O), was 13.1 and 8.5 μmol g–1 s–1 for pristine (chemically strained) and dry ball-milled (chemically and mechanically strained) oxides, respectively. The CO2 activation pathway (redox vs associative) was experimentally probed using in situ diffuse reflectance infrared Fourier transform spectroscopy. It was demonstrated that the mechanical strain increased up to 6 times the CO2 adsorption sites, though reducing their thermal stability. This result supports the mechanical actuation of the “carbonate”-bound species; the latter was in agreement with the density functional theory (DFT)-calculated C–O bond lengths and O–C–O angles. Ab initio studies shed light on the CO2 adsorption energy (Eads), suggesting a covalent bonding which is enhanced in the presence of doping and under tensile strain. Bader charge analysis probed the adsorbate/surface charge distribution and illustrated that CO2 interacts with the dual sites (acidic and basic ones) on the surface, leading to the formation of bidentate carbonate species. Density of states (DOS) studies revealed a significant Eg drop in the presence of double Ov and compressive strain, a finding with design implications in covalent type of interactions. To bridge this study with industrially important catalytic applications, Ni-supported catalysts were prepared using pristine and ball-milled oxides and evaluated for the dry reforming of methane reaction. Ball milling was found to induce modification of the metal–support interface and Ni catalyst reducibility, thus leading to an increase in the CH4 and CO2 conversions. This study opens new possibilities to manipulate the CO2 activation for a portfolio of heterogeneous reactions.

DFT calculations of double vacancies MoS2 catalyzing water gas shift reaction: S vacancies as electron bridge promote electron transfer to H2O and CO molecules

The poor activity of molybdenum disulfide (MoS2) basal plane is the key scientific problem to limit efficient hydrogen production. In this paper, MoS2 with single (VS-MoS2) and double sulfur vacancy (VS, S-MoS2) have been constructed and used for water gas shift reaction (WGSR). Results show that the adsorption energy of VS, S-MoS2 for CO molecule is −1.43 eV, which is 28.6 times and 1.1 times than original MoS2 and VS, S-MoS2, respectively. The energy barrier of the rate-determining step in the association mechanism of VS, S-MoS2 is 1.78 eV, which is 21% lower than pristine MoS2. S vacancies are active sites for CO and H2O adsorption. The delocalized electrons enrichment in S vacancies break the electron transfer barrier between the surface and molecules. Sulfur vacancies as medium make electrons continuously transferred to CO and H2O molecules.

Novel CeOx-modified In2O3 with stabilized Ce3+ states as a highly efficient photocatalyst for photoreduction of CO2 with CH4 or H2O

In this work, CeOx/In2O3 containing mass ratios of 0.1, 0.2 and 0.3 CeOx were prepared via a simple wet impregnation method and their photoactivity was evaluated for CO2 photoreduction with CH4 or H2O. HRTEM verified the formation of an oxide-oxide interface in CeOx/In2O3. XPS analysis revealed the presence of trivalent Ce3+ as the predominant species in CeOx/In2O3 that were formed due to the stabilization of Ce3+ states by In2O3. The presence of a higher content of Ce3+ reflected a strong interfacial contact between CeOx and In2O3. The optimized CeOx/In2O3 showed 4–7 times enhancement as compared to the unmodified In2O3 for CO2 photoreduction with CH4 or H2O reactions. The selectivity of CO and H2 were dependent on the reductant used. The selectivity of CO and H2 for CO2 photoreduction with CH4 remained at 33 % and 66 % after CeOx addition. Contrarily, the selectivity of H2 showed a gradual drop from 61 % to 18 % with an increase in CeOx loading when H2O was used as reductant. The improved activity of CeOx/In2O3 was because of (i) promoted charge transfer and separation due to strong interfacial contact and Type II band alignment, (ii) enhanced light absorption, and (iii) increased basic sites for CO2 adsorption.

Active sites and deactivation of room temperature CO oxidation on Co3O4 catalysts: combined experimental and computational investigations

Co3O4 is a well-known low temperature CO oxidation catalyst, but it often suffers from deactivation. We have thus examined room temperature (RT) CO oxidation on Co3O4 catalysts by operando DSC, TGA and MS measurements, as well as by pulsed chemisorption to differentiate the contributions of CO adsorption and reaction to CO2. Catalysts pretreated in oxygen at 400 °C are most active, with the initial interaction of CO and Co3O4 being strongly exothermic and with maximum amounts of CO adsorption and reaction. The initially high RT activity then levels-off, suggesting that the oxidative pretreatment creates an oxygen-rich reactive Co3O4 surface that upon reaction onset loses its most active oxygen. This specific active oxygen is not reestablished by gas phase O2 during the RT reaction. When the reaction temperature is increased to 150 °C, full conversion can be maintained for 100 h, and even after cooling back to RT. Apparently, deactivating species are avoided this way, whereas exposing the active surface even briefly to pure CO leads to immediate deactivation. Computational modeling using DFT helped to identify the CO adsorption sites, determine oxygen vacancy formation energies and the origin of deactivation. A new species of CO bonded to oxygen vacancies at RT was identified, which may block a vacancy site from further reaction unless CO is removed at higher temperature. The interaction between oxygen vacancies was found to be small, so that in the active state several lattice oxygen species are available for reaction in parallel.

Magnetically Doped Molybdenum Disulfide Layers for Enhanced Carbon Dioxide Capture.

Carbon capture and storage (CCS) technologies have the potential for reducing greenhouse gas emissions and creating clean energy solutions. One of the major aspects of the CCS technology is designing energy-efficient adsorbent materials for carbon dioxide capture. In this research, using a combination of first-principles theory, synthesis, and property measurements, we explore the CO2 gas adsorption capacity of MoS2 sheets via doping with iron, cobalt, and nickel. We show that substitutional dopants act as active sites for CO2 adsorption. The adsorption performance is determined to be dependent on the type of dopant species as well as its concentration. Nickel-doped MoS2 is found to be the best adsorbent for carbon capture with a relatively high gas adsorption capacity compared to pure MoS2 and iron- and cobalt-doped MoS2. Specifically, Brunauer-Emmett-Teller (BET) measurements show that 8 atom % Ni-MoS2 has the highest surface area (51 m2/g), indicating the highest CO2 uptake relative to the other concentrations and other dopants. Furthermore, we report that doping could lead to different magnetic solutions with changing electronic structures where narrow band gaps and the semimetallic tendency of the substrate are observed and can have an influence on the CO2 adsorption ability of MoS2. Our results provide a key strategy to the characteristic tendencies for designing highly active and optimized MoS2-based adsorbent materials utilizing the least volume of catalysts for CO2 capture and conversion.

Allotropes selection apropos of photocatalytic CO2 reduction from first principles studies

Materials engineering of allotropism provides a possible strategy for controling CO2 photoreduction into various C1 products. However, the understanding of the mechanism for tuning products selectivity through allotropism is still lacking. Herein, three structures of known phosphorus allotrope, i.e. black phosphorus (BP), fibrous red phosphorus (RP), and helical coil phosphorus (CP), were modelled as a CO2 reduction photocatalyst and studied by first principles density functional theory calculations. Three adsorption sites (P6C, P2B, and PT) of CO2 on the phosphorus allotropes were investigated. The most stable adsorption configuration for each allotrope was then selected for further study. The quantum topological analysis revealed that CO2 adsorption interaction on BP and RP exhibits physical binding of van der Waals interaction while CP shows physical binding of Keesom interaction. The CO2 adsorption interaction is shown to be crucial in determining the activation barrier for the initial proton-coupled electron transfer of CO2 → COOH. The pathways for different C1 products, including CO, HCOOH, C, CH2O, CH3OH, and CH4, were examined by comparing the rate determining step (RDS) obtained via Gibbs free energy analysis. RP and CP show higher selectivity towards the two- and four-electron C1 products. CP evidences a lower activation barrier for the two- and four-electron products RDS while BP exhibits higher selectivity towards the six- and eight-electron reduction products. The difference in selectivity of each of the allotropes was attributed to its distinct p-band center. This study divulges an important understanding on the possible product selectivity modulation for CO2 photoreduction based on allotropism.

Efficient One-Step Purification of C1 and C2 Hydrocarbons over CO2 in a New CO2-Selective MOF with a Gate-Opening Effect.

Removing CO2 impurity is an essential industrial process in the purification of hydrocarbons. The most promising strategy is the one-step collection of high-purity hydrocarbons by employing CO2-selective adsorbents, which requires improving the CO2 adsorption and separation behavior of adsorbents, especially the low-pressure performance under actual industrial conditions. Herein, we constructed a new flexible metal-organic framework [Zn(odip)0.5(bpe)0.5(CH3OH)]·0.5NMF·H2O (1) (H4odip = 5,5'-oxydiisophthalic acid, bpe = 1,2-bi(4-pyridyl)ethylene, and NMF = N-methylformamide) containing rich ether O adsorption sites in the channels that exhibits remarkable adsorption capacity for CO2 (118.7 cm3 g-1) due to the only gate-opening-type abrupt adsorption of CO2 at room temperature. Its low affinity for other competing gases enables it to deliver high selectivity for the adsorption of CO2 over C1 and C2 hydrocarbons. For equimolar mixtures of CO2-CH4 and CO2-C2H2, the selectivities are 376.0 and 13.2, respectively. Molecular simulations disclose more abundant adsorption sites for CO2 than hydrocarbons in 1. The breakthrough separation performances combined with remarkable stability and recyclability further verify that 1 is a promising adsorbent that can efficiently extract high-purity hydrocarbons through selective capture of CO2.

Bridge Sites of Au Surfaces Are Active for Electrocatalytic CO2 Reduction.

Prior in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) studies of electrochemical CO2 reduction catalyzed by Au, one of the most selective and active electrocatalysts to produce CO from CO2, suggest that the reaction proceeds solely on the top sites of the Au surface. This finding is worth updating with an improved spectroelectrochemical system where in situ IR measurements can be performed under real reaction conditions that yield high CO selectivity. Herein, we report the preparation of an Au-coated Si ATR crystal electrode with both high catalytic activity for CO2 reduction and strong surface enhancement of IR signals validated in the same spectroelectrochemical cell, which allows us to probe the adsorption and desorption behavior of bridge-bonded *CO species (*COB). We find that the Au surface restructures irreversibly to give an increased number of bridge sites for CO adsorption within the initial tens of seconds of CO2 reduction. By studying the potential-dependent desorption kinetics of *COB and quantifying the steady-state surface concentration of *COB under reaction conditions, we further show that *COB are active reaction intermediates for CO2 reduction to CO on this Au electrode. At medium overpotential, as high as 38% of the reaction occurs on the bridge sites.

Binary copper-bismuth catalysts for the electrochemical reduction of CO2: Study on surface properties and catalytic activity

A series of CuBi catalysts were prepared with different Bi loadings and tested for the electrochemical reduction of CO2 (ERCO2). The developed catalysts were tested on a filter-press cell, and the influence of the catholyte on the catalytic performance was assessed. Catalyst #20C was found to be very selective for formate production, with a faradaic efficiency (FE) of 86.4 %, when Cl– ions are present in the catholyte solution. The presence of weak CO2 adsorption sites on the catalyst surface favors the formation of non-coordinated and monodentate carbonates after CO2 adsorption, resulting in enhanced formate formation through an outer-sphere mechanism. For catalyst #50C, an unprecedented propane selectivity was recorded (FE of 85.4%), being the first high-efficiency catalyst for the ERCO2 to propane ever reported. This remarkable catalytic behavior was attributed to strong CO2 adsorption sites on the catalyst surface and higher CO2 and CO adsorption capacity. It is also proposed that a bidentate carbonate is a key intermediate for the ERCO2 to propane, which is preferably formed when strong Lewis acid and base sites are present on the catalyst surface.

Dual-Site Single-Atom Catalysts with High Performance for Three-Way Catalysis.

In response to growing levels of air pollution and emission regulations, novel three-way catalysts (TWCs) with high efficiency are highly coveted. Herein, a multi-step heating strategy to fabricate a unique dual-site catalyst composed of strongly coupled Pt and Pd atoms located in neighboring positions on the surface of CeO2 is demonstrated. Outstanding three-way catalytic performance is demonstrated, especially for NO elimination. Based on comprehensive investigations, the enhancement is attributed to the strong interactions between the neighboring Pt and Pd atoms, which can separately serve as active sites for CO and NO adsorption, efficiently reducing the energy barrier and accelerating the reaction rate. These findings not only contribute to designing and constructing next-generation catalysts, but also provide a promising opportunity to improve fuel efficiency and control emissions.

Highly Selective Photocatalytic Reduction of CO2 to CO Over Ru‐Modified Bi2MoO6

Photocatalytic CO2 reduction is a promising strategy for sustainable development. Optimizing the structure of photocatalysts to facilitate the separation of electron–hole pairs for improved performance is not only highly desirable but also challenging. Aiming to improve the photocatalytic reduction of CO2, Ru is selected and applied to modify Bi2MoO6. Compared to pure Bi2MoO6, Ru‐Bi2MoO6 exhibits substantially excellent photocatalytic activity in CO2 reduction with CO generation of 142.77 μmol−1 g−1 and selectivity of 100% under simulated sunlight. The enhancement might be attributed to the following: 1) Ru0 acting as an electron acceptor facilitates unique interaction and activation with CO, 2) Ru4+ doping enhances light absorption with addition impure energy levels within the bandgap, 3) ultrathin layers is in favor of improving the specific surface area and providing more exposed sites for CO2 adsorption and activation, and 4) interfaces between Ru and Bi2MoO6 accelerate charge transfer and separation, and electrons and holes are efficiently transferred to Ru and Ru4+, respectively, facilitating the reduction and oxidation reactions. This work provides a new approach to improve photocatalytic CO2 abatement and further presents valuable new insights into the design modification of photocatalytic systems.

Cuprous species distribution over CuCl/NaY dependent on acidity and their CO Adsorption/desorption performance study

• NaY zeolite was synthesized and its acidity was adjusted through NH 4 Cl exchange methods. • Three NaY-Cu samples with identical Cu loading presented different Cu + /Cu 2+ distribution dependent on their acidity. • NaY-Cu presented superior CO storage compared with NaY supports for strong Cu + CO bond. • Cu + cations located in site III and V dominated the CO adsorption compared to site I, II and IV. The impact of acidity on copper species distribution during solid exchange process of CuCl/NaY mixture and their CO storage performance were evaluated in this work. Firstly, the acidity of home-made Na form faujasite (NaY-10) was adjusted through ammonium ion exchange method to obtain its H from supports with different acidity. The bulk characterization results demonstrated the NaY-Cu structure collapsed in varying degrees during solid exchange process, but NaY-Cu samples exhibited superior CO storage ability compared with the corresponding NaY supports. DRIFTs of CO adsorption and simulation through first-principles calculations were further examined to reveal the CO adsorption sites and CO adsorption behaviors over hydroxyls, Na + cations and Cu + /Cu 2+ cations. Finally, the relation between faujasite acidity and CuCl distribution was systematically concluded and the CO adsorption/desorption difference between NaY supports and NaY-Cu samples was directly summarized to illustrate their industrial application potential.