CO2 Selectivity Research Articles

Ordering Bimetallic Cu-Pd Catalysts onto Orderly Mesoporous SrTiO3-Crystal Nanotubular Networks for Efficient Carbon Dioxide Photoreduction.

Artificial photosynthesis of fuels has garnered significant attention, with SrTiO3 emerging as a potential candidate for photocatalysis due to its exceptional physicochemical properties. However, selectively converting CO2 into fuels with desired reaction products remains a grand challenge. Herein, we design an updated method via an aging strategy based on the electrospinning technique to synthesize a single-crystalline Al-doped SrTiO3 nanotubular networks with self-assembled orderly mesopores, further modified by Cu-Pd alloy. It exhibits both high crystallinity and superior cross-linked mesoporous structures, effectively facilitating charge carrier transfer, photon utilization, and mass transfer, with a remarkable enhancement from 0.025 mmol h-1 m-2 to 1.090 mmol h-1 m-2 in the CO production rate. Meanwhile, the ordered arrangement of Cu and Pd atoms on the (111) surface can promote the rate-determining step (*CO2 to *COOH), which is also responsible for its good activity. The presence of CuO in the reaction confers a significant advantage for CO desorption, leading to a remarkable CO selectivity of 95.54 %. This work highlights new insights into developing advanced heterogeneous photocatalysts.

Ordering Bimetallic Cu‐Pd Catalysts onto Orderly Mesoporous SrTiO3‐Crystal Nanotubular Networks for Efficient Carbon Dioxide Photoreduction

AbstractArtificial photosynthesis of fuels has garnered significant attention, with SrTiO3 emerging as a potential candidate for photocatalysis due to its exceptional physicochemical properties. However, selectively converting CO2 into fuels with desired reaction products remains a grand challenge. Herein, we design an updated method via an aging strategy based on the electrospinning technique to synthesize a single‐crystalline Al‐doped SrTiO3 nanotubular networks with self‐assembled orderly mesopores, further modified by Cu−Pd alloy. It exhibits both high crystallinity and superior cross‐linked mesoporous structures, effectively facilitating charge carrier transfer, photon utilization, and mass transfer, with a remarkable enhancement from 0.025 mmol h−1 m−2 to 1.090 mmol h−1 m−2 in the CO production rate. Meanwhile, the ordered arrangement of Cu and Pd atoms on the (111) surface can promote the rate‐determining step (*CO2 to *COOH), which is also responsible for its good activity. The presence of CuO in the reaction confers a significant advantage for CO desorption, leading to a remarkable CO selectivity of 95.54 %. This work highlights new insights into developing advanced heterogeneous photocatalysts.

Optimizing Mo2C-based catalytic system for efficient CO2 conversion and CO selectivity through carbon-nitrogen supporting and potassium promotion

Preparing highly active, stable, and selective catalysts for the reverse water gas shift (RWGS) reaction is challenging because of the aggregation of the active catalyst at high RWGS reaction temperatures and deactivation of the active sites. Herein, we present a comparative evaluation and optimization of a molybdenum carbide system using a carbon-nitrogen (CN) support and alkali promotion. Hydrothermally prepared MoO3 nanorods were carburized at 700 °C using H2:CO (4:1) to prepare unsupported Mo2C, while CN-supported Mo2C (Mo2C@CN) was prepared using Mo-based metal-organic framework (Mo-MOF) as a sacrificial template. The as-prepared Mo2C@CN catalytic system was found to be highly active in the RWGS reaction in comparison with the unsupported Mo2C, where CO2 conversion percentage was around 76 % at 700 °C, combined with high CO selectivity (87 %) and very reduced CH4 selectivity (2 %). The addition of potassium as a promoter enhanced CO selectivity (99 %). The active catalyst performance was stable during the catalysis process and for up to 100 h, which imposes the effect of the CN support in preventing the aggregation of Mo2C and keeping its active sites in direct contact with the reactant. This work presents an effective strategy for improving the active catalyst dispersion and reducibility in synergy with the promoter effect to optimize the RWGS reaction output.

Thermodynamic modeling and performance analysis of chemical looping gasification combined with steam reforming for municipal solid waste: An Aspen Plus approach

Chemical looping gasification combined with steam reforming (CLG-SR) holds great promise for improving energy efficiency and streamlining the production of renewable H2 and synthetic fuels. In this investigation, the process underwent simulation and analysis using Aspen Plus, offering valuable insights into product outcomes, environmental impacts, and economic performance. The accuracy of the model was validated against experimental results from the literature, yielding a root mean square (RMS) of 4.17 %, thereby demonstrating its high feasibility. The findings demonstrate that within the temperature range of 700–800 °C, H2 achieves notable selectivity, reaching 60.68 % selectivity at 700 °C. When the steam-to-municipal solid waste (MSW) ratio surpasses 0.9, H2 demonstrates elevated selectivity. Notably, it is crucial to observe that the selectivity of CO2 also escalates concurrently with that of H2. Specifically, at steam-to-MSW ratio (SMR) of 0.9, the selectivity of H2 attains 60.72 %, whereas the selectivity of CO2 attains 27.69 %. Under these parameter conditions, H2, purified through pressure swing adsorption (PSA), constitutes 68.59 % of the total input H elements, leading to an impressive energy efficiency of 47.76 %. The economic analysis, based on the model, discloses a material consumption of 7.40 tons per ton of H2, resulting in a total production cost of 2487.20 USD per ton of H2. The study bears paramount strategic significance for advancing the in-depth research and development of chemical looping gasification technology.

Activation-free preparation of porous carbon fiber derived from phenolic resin for CO2 absorption

BackgroundIt is not uncommon to study the preparation of porous carbon materials for CO2 adsorption, but it is still a challenge to simultaneously achieve the good mechanical strength, porous structure, and efficient adsorption performance of porous carbon fibers. MethodsPorous carbon fibers with desirable morphology and selective CO2 adsorption were prepared using an activation-free method. The fibers were prepared through melt spinning of phenolic resin modified with polyvinyl butyral (PVB) and urea, followed by curing treatment, and then the pore structures were adjusted by controlling the carbonization temperature. Significant findingsThe porous carbon fibers prepared by carbonization at 900 °C not only had excellent CO2 adsorption (3.48 mmol/g) but also possessed desirable tensile strength (132 MPa). Those carbonized at 700 °C showcased CO2/N2 selectivity of 57 (Ideal adsorption solution theory (IAST), CO2: N2 =15:85), and tensile strength of 148 MPa, much higher than most fibers using other methods. The study revealed that the adsorption of CO2 was mainly performed by nitrogen-containing groups and physical function through pores ranging from 0.3 nm to 0.8 nm, and the micropores between 0.3 nm and 0.6 nm were conducive to the selective adsorption of CO2/N2.

Design and synthesis of Mg-HKUST-1/solid ionic liquid composites for CO2 capture with improved water stability

The water sensitivity HKUST-1, is a critical concern for realizing practical CO2 capture. Water stability and high CO2 adsorption are difficult to achieve simultaneously. Mg and piperazinium-based solid ionic liquids (SoILs) were incorporated into HKUST-1 to enhance its water stability and selective CO2 capture performance, respectively. The eco-friendly route was utilized for the synthesis of bimetallic Mg(x)-HKUST-1, employing water as the sole solvent with stirring and microwave treatment. The SoILs were incorporated into the pore structure of Mg(15)-HKUST-1 by wet impregnation. Among the different ratios of Mg used for the synthesis, 15 % Mg exhibited the highest improvement in CO2 capacity (5.32 mmol/g) and CO2/N2 selectivity (27) compared to the parent HKUST-1 (CO2 capacity, 4.2 mmol/g; CO2/N2 selectivity, 17). Once Mg(15)-HKUST-1 was impregnated with 10 % SoIL, the CO2 capture performance was further improved. In the stability study, 10 % SoIL/Mg(15)-HKUST-1 and Mg(15)-HKUST-1 preserved respectively 92.4 % and 85.3 % CO2 adsorption capacity after 20 days of exposure to a humid environment (60 % RH) at 298±5 K, an improvement compared to the HKUST-1 (26 %). The CO2 and N2 adsorption capacities of HKUST-1, Mg-HKUST-1, and SoIL/Mg-HKUST-1 composite were measured using a volumetric method and characterized using Brunauer-Emmett-Teller (BET) analysis, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA).

Rational design of spatial charge separation and targeted active site Cu for highly selective photocatalytic CO2 reduction to CH4

Photocatalytic CO2 reduction reaction (CO2RR) is usually constrained by sluggish kinetics and low product selectivity. Herein, a Cu-doping multi-tier hierarchical S-scheme heterostructure Cu-ZnIn2S4/ZIF-67 was fabricated, achieving highly efficient photocatalytic CO2RR under visible light without additional thermal input. At low pressure (absolute pressure 40 kPa), the optimized catalyst 2Cu-ZISF demonstrated a CH4 yield of 22.27 μmol g−1h−1 with a selectivity of 94.7 %. In situ XPS and EPR confirmed that the photogenerated charge transfer obeys an S-scheme mechanism, with Cu sites serving as electron-rich centers, facilitating spatial charge separation. In situ DRIFT detected reaction intermediates of photocatalytic CO2RR mechanism, and Gibbs free energy calculations via Density Functional Theory revealed that Cu incorporation significantly stabilizes surface CO* species, thus reducing CO(g) production and facilitating hydrogenation, thereby acting as targeted active sites for CH4 production. This work overcomes the limitations of slow reaction kinetics and offers an in-depth understanding of how to design effective S-scheme heterojunction photocatalysts and their charge transfer mechanisms.

Deciphering the dynamic structural evolution of oxygen vacancies enriched SrFe12O19 for efficient reverse water gas shift reaction

The Reverse Water-Gas Shift (rWGS) reaction is recognized as a potentially promising pathway to serve the dual purpose, possible shifting of CO2 from a linear economy to a circular and positive economic impact in the current industrial process. This study is engaged to develop a series of oxygen vacancies enriched M−type strontium hexaferrite (SrFe12O19) catalysts via doping of transition metals like Cu, Zn, Co, and Ni for the rWGS reaction. Cu-doped SrFe12O19 exhibited 100 % CO selectivity and a CO production rate of 2850 mmol h−1 gcat-1, at a comparatively lower temperature (500 °C), outpacing the performance of almost all non-precious metal-based catalytic systems. Moreover, the catalyst was active without the requirement of the H2 pre-reduction procedure and displayed remarkable stability tested up to 200 h without any significant deactivation, making it more industrially relevant. The characterization of as-prepared catalysts indicates the enrichment of oxygen vacancies and reducibility after the involvement of the dopant in the SrFe12O19 system. The formation of various iron species (Fe3O4, Fe3C, and Fe5C2) was revealed by the in-situ studies and post-reaction characterizations of the catalyst system, and their relative amounts were significantly affected by the nature of doping elements, which subsequently influenced the CO selectivity. The dynamic structural evolution and surface-adsorbedspecies were identified usingin-situ Raman and DRIFTS studies. Finally, the structure–activity relationship was rationalized through not only several ex-situ/in-situ characterization techniques but also an in-detailed Density functional theory (DFT) study.

TiO2 thermal stress deformation induced to promote photocatalytic CO2 reduction

Semiconductor photocatalytic reduction of CO2 is an effective means to achieve the goal of double carbon. TiO2 has received extensive attention as an excellent photocatalyst, but the adsorption of CO2 on the surface of TiO2 is not stable, which greatly inhibits the yield and selectivity of reduction products. In this work, wollastonite was used to reduce the melting temperature of TiO2 and in turn induce thermal stress deformation on the surface of the TiO2 lattice. Characterization and DFT results certified that the lattice stress deformation caused by the contraction of oxygen vacancy enables TiO2 to obtain better carrier transport efficiency and lower activation energy barrier, and also stabilizes the adsorption state of CO2 on the surface of TiO2 crystal, which effectively improved the reduction yield and selectivity of CO2. The CO yield is increased by 5.1 times, reaching up to 2.09 μmolg-1h−1, and the CO selectivity is as high as 91 %. These findings provide valuable insights for the development of efficient and selective photocatalysts for carbon dioxide transformation and pave the way for novel avenues in this research field.

Highly Efficient, Noble-Metal-Free, Fully Aqueous CO2 Photoreduction Sensitized by a Robust Organic Dye.

The development of efficient, selective, and durable CO2 photoreduction systems presents a long-standing challenge in full aqueous solutions owing to the presence of scarce CO2 and the fierce competition against H2 evolution, which is even more challenging when noble metals are not utilized. Herein, we present the facile decorations of four phosphonic acid groups on a donor-acceptor-type organic dye to obtain a water-soluble photosensitizer (4P-DPAIPN), which succeeds the excellent photophysical and photoredox properties of its prototype, exhibiting long-lived delayed fluorescence (>10 μs) in aqueous solutions. Combining 4P-DPAIPN with a cationic cobalt porphyrin catalyst has accomplished record-high apparent quantum yields of 9.4-17.4% at 450 nm for CO2-to-CO photoconversion among the precedented systems (maximum 13%) in fully aqueous solutions. Remarkable selectivity of 82-93% and turnover number of 2700 for CO production can also be achieved with this noble-metal-free system, outperforming a benchmarking ruthenium photosensitizer and a commercial organic dye under parallel conditions. Such high performances of 4P-DPAIPN can be well maintained under real sunlight. More impressively, no significant decomposition of 4P-DPAIPN was detected during the long-term photocatalysis. Eventually, the photoinduced electron transfer pathways were proposed.

Zn promoted GaZrOx Ternary Solid Solution Oxide Combined with SAPO-34 Effectively Converts CO2 to Light Olefins with Low CO Selectivity.

We proposed a new strategy for CO2 hydrogenation to prepare light olefins by introducing Zn into GaZrOx to construct ZnGaZrOx ternary oxides, which was combined with SAPO-34 to prepare a high-performance ZnGaZrOx/SAPO-34 tandem catalyst for CO2 hydrogenation to light olefins. By optimizing the Zn doping content, the ratio and mode of the two-phase composite, and the process conditions, the 3.5 %ZnGaZrOx/SAPO-34 tandem catalyst showed excellent catalytic performance and good high-temperature inhibition of the reverse water-gas shift (RWGS) reaction. The catalyst achieved 26.6 % CO2 conversion, 82.1 % C2 =-C4 = selectivity and 11.8 % light olefins yield. The ZnGaZrOx formed by introducing an appropriate amount of Zn into GaZrOx significantly enhanced the spillover H2 effect and also induced the generation of abundant oxygen vacancies to effectively promote the activation of CO2. Importantly, the RWGS reaction was also significantly suppressed at high temperatures, with the CO selectivity being only 46.1 % at 390 °C.

Highly efficient photoreduction of CO2 to CO: Synergistic optimisation of progressive electron transfer via Fe2+ and oxygen vacancies

The electron transfer in photocatalytic reaction, including electron transfer between the components in the catalyst, electron transfer between reactant molecules and catalysts. Fe2+/Fe3+ and oxygen vacancies (VOs) were simultaneously introduced in Fe-In2O3, the 5 wt% Fe-In2O3 exhibited a 13.7-fold increase in activity (4.80 mmol·g−1·h−1) compared to the In2O3 and a CO selectivity of approximately 84.32 %. Multiple in-situ techniques indicated that the doping of FeOX serves to effectively modulate the concentration of VOs, FeOX and In2O3 form a p-n heterojunction interfacial structure and match energy bands, promoting carrier separation. More importantly, Fe2+, In2+, and VOs serve as electron-donating adsorption sites, increasing the number of electrons received by CO2 and H2O, which causing pre-reduction activation of the reactant molecules. Eventually the dual-reduction reaction of CO2 and H2O were realized, subsequently, CO2 was selectively converted into CO through intermediate species such as formate. This study employs Fe2+ and VOs to synergistic optimize the progressive transfer of photogenerated electrons, and presents a novel approach for elucidating the catalytic mechanism.

Sub-nano porous graphene-based membranes enabled by in-situ-grown ZIF-8 for enhanced CO2 capture

Graphene oxide (GO) membranes hold promise for selective CO2 adsorption over N2 due to their carboxyl groups, making them attractive for flue gas CO2 capture. However, challenges such as limited carboxyl content, flexible nanosheets, and dense layer stacking hinder their N2/CO2 gas selectivity, pressure resistance, and permeability. In this study, we introduce a specific sub-nanometer framework structure within GO membranes by in-situ growing ZIF-8 nanocrystals. This novel approach, achieved through simultaneous infiltration of zinc nitrate and 2-methylimidazole precursors on both sides of the membrane, enhances CO2 capture and pressure resistance capabilities of resulting ZIF-8@GO composite membranes. Additionally, the incorporation of carboxylated wrinkled graphene (WG) and ethylenediamine (EDA) cross-linking agent molecules improves CO2 capture capability and introduces reinforced porous structures to enhance permeability. Experimental results demonstrate remarkable permeability, selectivity, and pressure resistance of the prepared ZIF-8@EDA-GO/WG composite membranes. Under a gas pressure of 0.2 MPa, permeability reaches 1850 GPU, with theoretical selectivity for N2/CO2 single gas and separation factors for mixed gases of 18.3 and 32.3, respectively, surpassing conventional GO membranes (3 GPU, 1.1, and 1.2). Even under elevated air pressure conditions (1.2 MPa), the composite membranes maintain a theoretical selectivity of 13.4. Our CO2 capture membrane design strategy not only advances the development of functional membranes but also contributes to mitigating CO2 emissions from flue gas, thereby combating global warming.

Cobalt(VI)-oxo species-mediated selective oxidation of electron-rich organic contaminants by Co-loaded hydroxylated g-C3N4 with high resistance to an inhibitory effect of background constituents

Understanding of the selectivity of high-valent cobalt-oxo species (Co(IV)O) toward diverse organic pollutants with different characteristics in the presence of background constituents remains limited. Here, we prepared Co-loaded hydroxyl group-grafted graphitic carbon nitride (Co-OHCN) using a facile method for the effective formation of Co(IV)O. The role of the hydroxyl group in anchoring Co ions was investigated using several characterization methods (TEM, XRD, FT-IR, and XPS). Co-OHCN exhibited superior efficiency in degrading 4-chlorophenol (4-CP) (98.0 % ± 0.3 %) within 15 min of peroxymonosulfate (PMS) activation reaction. In the Co-OHCN/PMS system, Co(IV)O had the highest steady-state concentration ([Co(IV)O] = 1.40 × 10−10 M), significantly exceeding that of other reactive oxygen species (ROS) ([SO4−] = 9.22 × 10−13 M, [OH] = 1.82 × 10−13 M). The dominant role of Co(IV)O in 4-CP degradation was further revealed through scavenger tests, probe methods, and electrochemical analysis. Additionally, the anti-interference of Co(IV)O in the degradation of electron-rich organic substrates to background constituents (NOM and halide ions) was systemically validated using three organic pollutants with different ionization potential values (diclofenac, 4-CP, and benzoic acid). This study provides insight into an efficient strategy for Co(IV)O -mediated pollutant elimination and organic substrate-dependent selectivity of Co(IV)O during water decontamination.

Controlling CO2 hydrogenation selectivity by tuning surface properties of Cu/ZnxAlyOz catalysts

CO2 hydrogenation to methanol and/or dimethyl ether (DME) holds promise for mitigating greenhouse gas effects and addressing energy scarcity. However, the relationship between product selectivity and the collective nature of the catalysts remains ambiguous due to the intricate reaction network. Here, a series of Cu/ZnxAlyOz catalysts with different surface properties have been engineered by manipulating the Zn/Al ratio to achieve product controllability for CO2 hydrogenation. The results unveil the pivotal role of the H2 dissociation capability in governing CO2 conversion, which is regulated by the concentration of Cu0 species. Furthermore, the number of surface hydroxyl groups, the proportion of moderately strong basic sites and moderately strong acidic sites show desirable linear correlations with the selectivity of CO, CH3OH, and DME, respectively. Importantly, the ZnAl2O4-Al2O3 or Cu-ZnAl2O4-Al2O3 interface notably enhances moderately strong acidic sites, aiding methanol dehydration to DME. This work offers a comprehensive guide to the rational design of catalysts for oriented product synthesis from CO2 hydrogenation.

Universal Formation of Single Atoms from Molten Salt for Facilitating Selective CO2 Reduction.

Clarifying the formation mechanism of single-atom sites guides the design of emerging single-atom catalysts (SACs) and facilitates the identification of the active sites at atomic scale. Herein, a molten-salt atomization strategy is developed for synthesizing zinc (Zn) SACs with temperature universality from 400 to 1000/1100°C and an evolved coordination from Zn-N2Cl2 to Zn-N4. The electrochemical tests and in situ attenuated total reflectance-surface-enhanced infrared absorption spectroscopy confirm that the Zn-N4 atomic sites are active for electrochemical carbon dioxide (CO2) conversion to carbon monoxide (CO). In a strongly acidic medium (0.2m K2SO4, pH = 1), the Zn SAC formed at 1000°C (Zn1NC) containing Zn-N4 sites enables highly selective CO2 electroreduction to CO, with nearly 100% selectivity toward CO product in a wide current density range of 100-600mAcm-2. During a 50 h continuous electrolysis at the industrial current density of 200mAcm-2, Zn1NC achieves Faradaic efficiencies greater than 95% for CO product. The work presents a temperature-universal formation of single-atom sites, which provides a novel platform for unraveling the active sites in Zn SACs for CO2 electroreduction and extends the synthesis of SACs with controllable coordination sites.

Mechanistic insight into electrochemical CO2 reduction on Mo single-atom catalyst and its hydrate: A computational study

By using density functional theory calculation, we investigated the CO2 reduction to CH4 on molybdenum-doped graphene (Mo@Gra) and identified two major paths from the HCOO* and COOH* intermediates with different onset potential. Both HCOO* and COOH* would continent hydrogenating to CH4 by an eight proton-electron coupling transfer process via HCOO path and COOH path. By the HCOO path, the formation of HCOO* is exergonic and the potential determining step (PDS) is OH* to H2O* by an endergonic process of 0.70 eV. On the other hand, the formation of COOH* from CO2* is endergonic with the same PDS and a limiting potential (UL) of –0.70 V. In addition, nitrogen coordinated Mo-graphene (Mo@3N-Gra) also illustrated for CO2 reduction and the corresponding UL is found to be –1.88 V. In addition, we also explore the mechanisms of CO2 reduction on the water pre-adsorption surface for realistic experiments. The UL required to overcome was reduced to –0.25 V for 3H2O*Mo@Gra with three H2O co-adsorption environment, suggesting the catalytic performance can be enhanced by water promotion effect. Two structures of hydrated structures, 2H2O*OH*Mo@3N-Gra and 3H2O*Mo@3N-Gra, were selected for stimulate realistic experiments. Compared to the Mo@3N-Gra catalyst, the UL reduces to –0.48 and –0.70 V for 2H2O*OH*Mo@3N-Gra and 3H2O*Mo@3N-Gra, respectively. Although, Mo-N doped graphene has better CO2 capture ability and selectivity, it needs more onset potential to produce CH4. Our calculations demonstrated that the electrocatalytic performance can be enhanced by the hydration effect.

Efficient electroreduction of CO2 into CO in flow cell with a metal-free ternary-doped porous carbon

Herein, a series of metal-free N, P, and Se ternary-doped porous carbon electrocatalysts, referred as "SePNC" as metal-free electrocatalysts, was prepared. This study shows that, the optimal electrocatalyst of SePNC-1050, which prepared at 1050 ℃, has high CO selectivity with Faraday efficiency of 94.8% for CO, and a byproduct of 5.2% H2. After continuous electrolysis for 12 h, the Faraday efficiency and current density remained relatively high, around 95.9% and 80.2% of the initial values, respectively, indicating it has long-term operation stability. This mainly due to the synergistic effect of doped N, P, and Se, as well as the high specific surface area of SePNC-1050 (970.0 m2g−1). This work would provide a good reference to develop high-performance metal-free CO2 reduction reaction (CO2RR) electrocatalysts in future.

Polyacrylate modified Cu electrode for selective electrochemical CO2 reduction towards multicarbon products

Highly selective production of value-added multicarbon (C2+) products via electrochemical CO2 reduction reaction (eCO2RR) on polycrystalline copper (Cu) remains challenging. Herein, the facile surface modification using poly (α-ethyl cyanoacrylate) (PECA) is presented to greatly enhance the C2+ selectivity for eCO2RR over polycrystalline Cu, with Faradaic efficiency (FE) towards C2+ products increased from 30.1% for the Cu electrode to 72.6% for the obtained Cu-PECA electrode at −1.1 V vs. reversible hydrogen electrode (RHE). Given the well-determined FEs towards C2+ products, the partial current densities for C2+ production could be estimated to be −145.4 mA cm−2 for the Cu-PECA electrode at −0.9 V vs. RHE in a homemade flow cell. In-situ spectral characterizations and theoretical calculations reveal that PECA featured with electron-accepting −C≡N and −COOR groups decorated onto the Cu electrode could inhibit the adsorption of *H intermediates and stabilize the *CO intermediates, given the redistributed interfacial electron density and the raised energy level of d-band center (Ed) of Cu active sites, thus facilitating the C–C coupling and then the C2+ selective production. This study is believed to be guidable to the modification of electrocatalysts and electrodes with polymers to steer the surface adsorption behaviors of reaction intermediates to realize practical eCO2RR towards value-added C2+ products with high activity and selectivity.

Stabilized ε-Fe2C catalyst with Mn tuning to suppress C1 byproduct selectivity for high-temperature olefin synthesis

Accurately controlling the product selectivity in syngas conversion, especially increasing the olefin selectivity while minimizing C1 byproducts, remains a significant challenge. Epsilon Fe2C is deemed a promising candidate catalyst due to its inherently low CO2 selectivity, but its use is hindered by its poor high-temperature stability. Herein, we report the successful synthesis of highly stable ε-Fe2C through a N-induced strategy utilizing pyrolysis of Prussian blue analogs (PBAs). This catalyst, with precisely controlled Mn promoter, not only achieved an olefin selectivity of up to 70.2% but also minimized the selectivity of C1 byproducts to 19.0%, including 11.9% CO2 and 7.1% CH4. The superior performance of our ε-Fe2C-xMn catalysts, particularly in minimizing CO2 formation, is largely attributed to the interface of dispersed MnO cluster and ε-Fe2C, which crucially limits CO to CO2 conversion. Here, we enhance the carbon efficiency and economic viability of the olefin production process while maintaining high catalytic activity.