Flame-made ternary Pd-In2O3-ZrO2 catalyst with enhanced oxygen vacancy generation for CO2 hydrogenation to methanol

Tuning the electronic structure and SMSI by integrating trimetallic sites with defective ceria for the CO2 reduction reaction

Heterogeneous catalysts have emerged as a potential key for closing the carbon cycle by converting carbon dioxide (CO2) into value-added chemicals. In this work, we report a highly active and stable ceria (CeO2)-based electronically tuned trimetallic catalyst for CO2 to CO conversion. A unique distribution of electron density between the defective ceria support and the trimetallic nanoparticles (of Ni, Cu, Zn) was established by creating the strong metal support interaction (SMSI) between them. The catalyst showed CO productivity of 49,279 mmol g-1 h-1 at 650 °C. CO selectivity up to 99% and excellent stability (rate remained unchanged even after 100 h) stemmed from the synergistic interactions among Ni-Cu-Zn sites and their SMSI with the defective ceria support. High-energy-resolution fluorescence-detection X-ray absorption spectroscopy (HERFD-XAS) confirmed this SMSI, further corroborated by in situ electron energy loss spectroscopy (EELS) and density functional theory (DFT) simulations. The in situ studies (HERFD-XAS & EELS) indicated the key role of oxygen vacancies of defective CeO2 during catalysis. The in situ transmission electron microscopy (TEM) imaging under catalytic conditions visualized the movement and growth of active trimetallic sites, which completely stopped once SMSI was established. In situ FTIR (supported by DFT) provided a molecular-level understanding of the formation of various reaction intermediates and their conversion into products, which followed a complex coupling of direct dissociation and redox pathway assisted by hydrogen, simultaneously on different active sites. Thus, sophisticated manipulation of electronic properties of trimetallic sites and defect dynamics significantly enhanced catalytic performance during CO2 to CO conversion.

Generating Strong Metal-Support Interaction and Oxygen Vacancies in Cu/MgAlOx Catalysts by CO2 Treatment for Enhanced CO2 Hydrogenation to Methanol

Strong metal-support interactions (SMSIs) are essential for optimizing the performance of supported metal catalysts by tuning the metal-oxide interface structures. This study explores the hydrogenation of CO2 to methanol over Cu-supported catalysts, focusing on the synergistic effects of strong metal-support interaction (SMSI) and oxygen vacancies introduced by the CO2 treatment to the catalysts on the catalytic performance. Cu nanoparticles were immobilized on Mg-Al layered double oxide (LDO) supports and modified with nitrate ions to promote oxygen vacancy generation. Further calcination in a 15% CO2/85% N2 atmosphere at various temperatures not only resulted in the formation of SMSI and electronic metal-support interaction (EMSI) between Cu and MgO, but also generated abundant oxygen vacancies on MgO. The optimized 7.5%Cu/MA-C700 catalyst (Cu supported on MgAl-LDO treated in CO2 at 700 °C) exhibited significantly higher methanol production and turnover frequency compared to the air-calcined counterparts. In situ FTIR studies further revealed that oxygen vacancies led to the formation of more monodentate formate species, thus enhancing methanol production. This research provides a novel approach to engineering the catalyst interface structure and the interaction between the active metal and the support, particularly for the irreducible metal oxide support, for efficient hydrogenation of CO2 to methanol.

Performance and Stability of Corundum-type In2O3 Catalyst for Carbon Dioxide Hydrogenation to Methanol

Carbon dioxide hydrogenation to methanol is a key chemical reaction to store energy in chemical bonds, using carbon dioxide as an energy sink. Indium oxide is amongst the most promising candidates for replacing the copper and zinc oxide catalyst, which is industrially applied for syngas mixtures but less idoneous for educts with carbon dioxide due to instability reasons. The polymorph of indium oxide and the operating conditions remain to be optimized for optimal and stable performance. Indium oxide catalysts containing different rhombohedral and cubic phase ratios were synthesized using a solvothermal method and evaluated in an ideally mixed gas phase reactor. The pure rhombohedral catalyst shows the best performance in terms of yield to methanol, selectivity, and stability. The phase stability was assessed using synchrotron in situ XRD and Rietveld refinement, shedding light on the stability of the different phases at extended operating conditions. Depending on the flow rate, temperature, and hydrogen partial pressure, a rhombohedral to cubic transition occurs, ultimately yielding inactive metallic indium. If present, cubic In2O3 serves as nuclei to induce the cubic to rhombohedral transition, hampering performance. These results allow for a more rational catalyst design and fine-tuning of the operating conditions to ensure optimal and stable performance.

Controllable Active Intermediate in CO2 Hydrogenation Enabling Highly Selective N,N-Dimethylformamide Synthesis via N-Formylation

N,N-Dimethylformamide (DMF) is a widely used solvent, and its green and low-carbon synthesis methods are in high demand. Herein, we report a new approach for DMF synthesis using a continuous flow reaction system with a fixed-bed reactor and a ZnO-TiO2 solid solution catalyst. This catalyst effectively utilizes CO2, H2, and dimethylamine (DMA) as feedstocks, demonstrating performance with 99% DMF selectivity and single-pass DMA conversion approaching thermodynamic equilibrium. Moreover, the catalyst demonstrates good stability, with no signs of deactivation over 1000 h of continuous operation. The key to superior activity lies in the synergetic effect of the Zn and Ti sites, which facilitates the formation of active formate species. These species act as crucial intermediates, reacting with DMA to produce DMF. Importantly, the slow hydrogenation kinetics of the formate species prevent the formation of CH2O* species, thereby suppressing the formation of the undesired byproduct, trimethylamine. This work underscores the potential of kinetically controlling active intermediates in CO2 hydrogenation to prepare high-value-added chemicals by coupling them to platform molecules. It presents a promising strategy for the efficient utilization of CO2 resources and offers a valuable solution for large-scale DMF synthesis.

Ce Promotion of In2O3 for Electrochemical Reduction of CO2 to Formate

In2O3 is a promising electrocatalyst for CO2 electroreduction (CO2ER) to formate. In2O3 nanoparticles doped with Pd, Ni, Co, Zr, and Ce promoters using flame-spray pyrolysis were characterized and evaluated in a gas diffusion electrode for the CO2ER. Doping results in slight shifts of the In binding energy as probed by XPS, which correlates with a change of the Faradaic efficiency to formate (FEformate) in the order Ce-doped In2O3 > Zr-doped In2O3 > In2O3 > Pd-doped In2O3 > Ni-doped In2O3 > Co-doped In2O3. However, the differences in CO2ER performance are caused mainly by the different extent of In2O3 reduction. Co-doped In2O3 is prone to complete reduction to a stable Co-In alloy with a low FEformate due to a high hydrogen evolution activity. The stabilizing effect of Ce on In2O3 is further demonstrated by an X-ray absorption spectroscopy study of a set of Ce-doped In2O3 samples (10, 50, 90 at%), highlighting that reduction of In2O3 is suppressed with increasing Ce content. Optimum performance in terms of FEformate is obtained at a Ce content of 10 at%, which is attributed to the stabilization of In2O3 under negative bias up to -2 V. At higher Ce content, less active CeO2 is formed. The highest FEformate of 86% observed for In2O3 doped with 10 at% Ce, at a current density of 150 mA/cm2, compares favorably with a FEformate of 78% for In2O3.

Design Principles of Catalytic Materials for CO2 Hydrogenation to Methanol

Heterogeneous catalysts are essential for thermocatalytic CO2 hydrogenation to methanol, a key route for sustainable production of this vital platform chemical and energy carrier. The primary catalyst families studied include copper-based, indium oxide-based, and mixed zinc-zirconium oxides-based materials. Despite significant progress in their design, research is often compartmentalized, lacking a holistic overview needed to surpass current performance limits. This perspective introduces generalized design principles for catalytic materials in CO2-to-methanol conversion, illustrating how complex architectures with improved functionality can be assembled from simple components (e.g., active phases, supports, and promoters). After reviewing basic concepts in CO2-based methanol synthesis, engineering principles are explored, building in complexity from single to binary and ternary systems. As active nanostructures are complex and strongly depend on their reaction environment, recent progress in operando characterization techniques and machine learning approaches is examined. Finally, common design rules centered around symbiotic interfaces integrating acid-base and redox functions and their role in performance optimization are identified, pinpointing important future directions in catalyst design for CO2 hydrogenation to methanol.

Prediction of perovskite oxygen vacancies for oxygen electrocatalysis at different temperatures

Efficient catalysts are imperative to accelerate the slow oxygen reaction kinetics for the development of emerging electrochemical energy systems ranging from room-temperature alkaline water electrolysis to high-temperature ceramic fuel cells. In this work, we reveal the role of cationic inductive interactions in predetermining the oxygen vacancy concentrations of 235 cobalt-based and 200 iron-based perovskite catalysts at different temperatures, and this trend can be well predicted from machine learning techniques based on the cationic lattice environment, requiring no heavy computational and experimental inputs. Our results further show that the catalytic activity of the perovskites is strongly correlated with their oxygen vacancy concentration and operating temperatures. We then provide a machine learning-guided route for developing oxygen electrocatalysts suitable for operation at different temperatures with time efficiency and good prediction accuracy.

Electrostatic Self-Assembly Synthesis of Pd/In2O3 Nanocatalysts with Improved Performance Toward CO2 Hydrogenation to Methanol

CO2 hydrogenation to methanol has emerged as a promising strategy for achieving carbon neutrality and mitigating global warming, in which the supported Pd/In2O3 catalysts are attracting great attention due to their high selectivity. Nonetheless, conventional impregnation methods induce strong metal-support interaction (SMSI) between Pd and In2O3, which leads to the excessive reduction of In2O3 and the formation of undesirable PdIn alloy in hydrogen-rich atmospheres. Herein, we innovatively synthesized Pd/In2O3 nanocatalysts by the electrostatic self-assembly process between surface-modified composite precursors with opposite charges. And the organic ligands concurrently serve as Pd nanoparticle protective agents. The resultant Pd/In2O3 nanocatalyst demonstrates the homogeneous distribution of Pd nanoparticles with controllable sizes on In2O3 supports and the limited formation of PdIn alloy. As a result, it exhibits superior selectivity and stability compared to the counterparts synthesized by the conventional impregnation procedure. Typically, it attains a maximum methanol space-time yield of 0.54 gMeOH h-1gcat -1 (300 °C, 3.5 MPa, 21,000 mL gcat -1 h-1). Notably, the correlation characterization results reveal the significant effect of small-size, highly dispersed Pd nanoparticles in mitigating MSI. These results provide an alternative strategy for synthesizing highly efficient Pd/In2O3 catalysts and offer a new insight into the strong metal-support interaction.

Active Sites for CO2 Hydrogenation to Methanol: Mechanistic Insights and Reaction Control

Catalytic CO2 conversion to methanol is a promising way to extenuate the adverse effects of CO2 emission, global warming and energy shortage. Understanding the fundamental features of CO2 activation and hydrogenation at the molecular level is essential for carbon utilization and sustainable chemical production in the current climate crisis. This review explores the recent advances in understanding the design of catalysts with desired active sites, including single-atom, dual-atom, interface, defects/vacancies and promoters/dopants. We focused on the design of various catalytic systems to enhance their catalytic performances by stabilizing active metal in a catalyst, identifying the unique structure of active species, and engineering coordination environments of active sites. Mechanistic insights provided by advanced operando and in situ spectroscopies were also discussed. Moreover, the review highlights the key factors affecting active sites and reaction mechanisms, such as local environments, oxidation states, and metal-support interactions. By integrating recent advancements and relating knowledge gaps, this review aims to endow an inclusive overview of the field and guide future research toward more efficient and selective catalysts for CO2 hydrogenation to methanol.

Sulfur filling activates vacancy-induced C-C bond cleavage in polyol electrooxidation

Using the electrochemical polyol oxidation reaction (POR) to produce formic acid over nickel-based oxides/hydroxides (NiO x H y ) is an attractive strategy for the electrochemical upgrading of biomass-derived polyols. The key step in the POR, i.e. the cleavage of the C-C bond, depends on an oxygen-vacancy-induced mechanism. However, a high-energy oxygen vacancy is usually ineffective for Schottky-type oxygen-vacancy-rich β-Ni(OH)2 (VSO-β-Ni(OH)2). As a result, both β-Ni(OH)2 and VSO-β-Ni(OH)2 cannot continuously catalyze oxygen-vacancy-induced C-C bond cleavage during PORs. Here, we report a strategy of oxygen-vacancy-filling with sulfur to synthesize a β-Ni(OH)2 (S-VO-β-Ni(OH)2) catalyst, whose oxygen vacancies are protected by filling with sulfur atoms. During PORs over S-VO-β-Ni(OH)2, the pre-electrooxidation-induced loss of sulfur and structural self-reconstruction cause the in-situ generation of stable Frenkel-type oxygen vacancies for activating vacancy-induced C-C bond cleavage, thus leading to excellent POR performances. This work provides an intelligent approach for guaranteeing the sustaining action of the oxygen-vacancy-induced catalytic mechanism in electrooxidation reactions.

Quantum Spin Exchange Interactions Trigger O p Band Broadening for Enhanced Aqueous Zinc-Ion Battery Performance

The pressing demand for large-scale energy storage solutions has propelled the development of advanced battery technologies, among which zinc-ion batteries (ZIBs) are prominent due to their resource abundance, high capacity, and safety in aqueous environments. However, the use of manganese oxide cathodes in ZIBs is challenged by their poor electrical conductivity and structural stability, stemming from the intrinsic properties of MnO2 and the destabilizing effects of ion intercalation. To overcome these limitations, our research delves into atomic-level engineering, emphasizing quantum spin exchange interactions (QSEI). These essential for modifying electronic characteristics, can significantly influence material efficiency and functionality. We demonstrate through density functional theory (DFT) calculations that enhanced QSEI in manganese oxides broadens the O p band, narrows the band gap, and optimizes both proton adsorption and electron transport. Empirical evidence is provided through the synthesis of Ru-MnO2 nanosheets, which display a marked increase in energy storage capacity, achieving 314.4 mAh g-1 at 0.2 A g-1 and maintaining high capacity after 2000 cycles. Our findings underscore the potential of QSEI to enhance the performance of TMO cathodes in ZIBs, pointing to new avenues for advancing battery technology.

Spinel Nanostructures for the Hydrogenation of CO2 to Methanol and Hydrocarbon Chemicals

Composite oxides have been widely applied in the hydrogenation of CO/CO2 to methanol or as the component of bifunctional oxide-zeolite for the synthesis of hydrocarbon chemicals. However, it is still challenging to disentangle the stepwise formation mechanism of CH3OH at working conditions and selectively convert CO2 to hydrocarbon chemicals with narrow distribution. Here, we investigate the reaction network of the hydrogenation of CO2 to methanol over a series of spinel oxides (AB2O4), among which the Zn-based nanostructures offer superior performance in methanol synthesis. Through a series of (quasi) in situ spectroscopic characterizations, we evidence that the dissociation of H2 tends to follow a heterolytic pathway and that hydrogenation ability can be regulated by the combination of Zn with Ga or Al. The coordinatively unsaturated metal sites over ZnAl2Ox and ZnGa2Ox originating from oxygen vacancies (OVs) are evidenced to be responsible for the dissociative adsorption and activation of CO2. The evolution of the reaction intermediates, including both carbonaceous and hydrogen species at high temperatures and pressures over the spinel oxides, has been experimentally elaborated at the atomic level. With the integration of a series of zeolites or zeotypes, high selectivities of hydrocarbon chemicals with narrow distributions can be directly produced from CO2 and H2, offering a promising route for CO2 utilization.

Facilitating the dry reforming of methane with interfacial synergistic catalysis in an Ir@CeO2-x catalyst

The dry reforming of methane provides an attractive route to convert greenhouse gases (CH4 and CO2) into valuable syngas, so as to resolve the carbon cycle and environmental issues. However, the development of high-performance catalysts remains a huge challenge. Herein, we report a 0.6% Ir/CeO2-x catalyst with a metal-support interface structure which exhibits high CH4 (~72%) and CO2 (~82%) conversion and a CH4 reaction rate of ~973 μmolCH4 gcat-1 s-1 which is stable over 100 h at 700 °C. The performance of the catalyst is close to the state-of-the-art in this area of research. A combination of in situ spectroscopic characterization and theoretical calculations highlight the importance of the interfacial structure as an intrinsic active center to facilitate the CH4 dissociation (the rate-determining step) and the CH2* oxidation to CH2O* without coke formation, which accounts for the long-term stability. The catalyst in this work has a potential application prospect in the field of high-value utilization of carbon resources.

The Enigma of Methanol Synthesis by Cu/ZnO/Al2O3-Based Catalysts

The activity and durability of the Cu/ZnO/Al2O3 (CZA) catalyst formulation for methanol synthesis from CO/CO2/H2 feeds far exceed the sum of its individual components. As such, this ternary catalytic system is a prime example of synergy in catalysis, one that has been employed for the large scale commercial production of methanol since its inception in the mid 1960s with precious little alteration to its original formulation. Methanol is a key building block of the chemical industry. It is also an attractive energy storage molecule, which can also be produced from CO2 and H2 alone, making efficient use of sequestered CO2. As such, this somewhat unusual catalyst formulation has an enormous role to play in the modern chemical industry and the world of global economics, to which the correspondingly voluminous and ongoing research, which began in the 1920s, attests. Yet, despite this commercial success, and while research aimed at understanding how this formulation functions has continued throughout the decades, a comprehensive and universally agreed upon understanding of how this material achieves what it does has yet to be realized. After nigh on a century of research into CZA catalysts, the purpose of this Review is to appraise what has been achieved to date, and to show how, and how far, the field has evolved. To do so, this Review evaluates the research regarding this catalyst formulation in a chronological order and critically assesses the validity and novelty of various hypotheses and claims that have been made over the years. Ultimately, the Review attempts to derive a holistic summary of what the current body of literature tells us about the fundamental sources of the synergies at work within the CZA catalyst and, from this, suggest ways in which the field may yet be further advanced.

Low-nuclearity CuZn ensembles on ZnZrOx catalyze methanol synthesis from CO2

Metal promotion could unlock high performance in zinc-zirconium catalysts, ZnZrOx, for CO2 hydrogenation to methanol. Still, with most efforts devoted to costly palladium, the optimal metal choice and necessary atomic-level architecture remain unclear. Herein, we investigate the promotion of ZnZrOx catalysts with small amounts (0.5 mol%) of diverse hydrogenation metals (Re, Co, Au, Ni, Rh, Ag, Ir, Ru, Pt, Pd, and Cu) prepared via a standardized flame spray pyrolysis approach. Cu emerges as the most effective promoter, doubling methanol productivity. Operando X-ray absorption, infrared, and electron paramagnetic resonance spectroscopic analyses and density functional theory simulations reveal that Cu0 species form Zn-rich low-nuclearity CuZn clusters on the ZrO2 surface during reaction, which correlates with the generation of oxygen vacancies in their vicinity. Mechanistic studies demonstrate that this catalytic ensemble promotes the rapid hydrogenation of intermediate formate into methanol while effectively suppressing CO production, showcasing the potential of low-nuclearity metal ensembles in CO2-based methanol synthesis.

Mitigating the Poisoning Effect of Formate during CO2 Hydrogenation to Methanol over Co-Containing Dual-Atom Oxide Catalysts

During the hydrogenation of CO2 to methanol over mixed-oxide catalysts, the strong adsorption of CO2 and formate poses a barrier for H2 dissociation, limiting methanol selectivity and productivity. Here we show that by using Co-containing dual-atom oxide catalysts, the poisoning effect can be countered by separating the site for H2 dissociation and the adsorption of intermediates. We synthesized a Co- and In-doped ZrO2 catalyst (Co-In-ZrO2) containing atomically dispersed Co and In species. Catalyst characterization showed that Co and In atoms were atomically dispersed and were in proximity to each other owing to a random distribution. During the CO2 hydrogenation reaction, the Co atom was responsible for the adsorption of CO2 and formate species, while the nearby In atoms promoted the hydrogenation of adsorbed intermediates. The cooperative effect increased the methanol selectivity to 86% over the dual-atom catalyst, and methanol productivity increased 2-fold in comparison to single-atom catalysts. This cooperative effect was extended to Co-Zn and Co-Ga doped ZrO2 catalysts. This work presents a different approach to designing mixed-oxide catalysts for CO2 hydrogenation based on the preferential adsorption of substrates and intermediates instead of promoting H2 dissociation to mitigate the poisonous effects of substrates and intermediates.

A Ce-CuZn catalyst with abundant Cu/Zn-OV-Ce active sites for CO2 hydrogenation to methanol

CO2 hydrogenation to chemicals and fuels is a significant approach for achieving carbon neutrality. It is essential to rationally design the chemical structure and catalytic active sites towards the development of efficient catalysts. Here we show a Ce-CuZn catalyst with enriched Cu/Zn-OV-Ce active sites fabricated through the atomic-level substitution of Cu and Zn into Ce-MOF precursor. The Ce-CuZn catalyst exhibits a high methanol selectivity of 71.1% and a space-time yield of methanol up to 400.3 g·kgcat-1·h-1 with excellent stability for 170 h at 260 °C, comparable to that of the state-of-the-art CuZnAl catalysts. Controlled experiments and DFT calculations confirm that the incorporation of Cu and Zn into CeO2 with abundant oxygen vacancies can facilitate H2 dissociation energetically and thus improve CO2 hydrogenation over the Ce-CuZn catalyst via formate intermediates. This work offers an atomic-level design strategy for constructing efficient multi-metal catalysts for methanol synthesis through precise control of active sites.

Unlocking a Dual-Channel Pathway in CO2 Hydrogenation to Methanol over Single-Site Zirconium on Amorphous Silica

Converting CO2 into methanol on a large scale is of great significance in the sustainable methanol economy. Zirconia species are considered to be an essential support in Cu-based catalysts due to their excellent properties for CO2 adsorption and activation. However, the evolution of Zr species during the reaction and the effect of their structure on the reaction pathways remain unclear. Herein, single-site Zr species in an amorphous SiO2 matrix are created by enhancing the Zr-Si interaction in Cu/ZrO2 -SiO2 catalysts. In situ X-ray absorption spectroscopy (XAS) reveals that the coordination environment of single-site Zr is sensitive to the atmosphere and reaction conditions. We demonstrate that the CO2 adsorption occurs preferably on the interface of Cu and single-site Zr rather than on ZrO2 nanoparticles. Methanol synthesis in reverse water-gas-shift (RWGS)+CO-hydro pathway is verified only over single-dispersed Zr sites, whereas the ordinary formate pathway occurs on ZrO2 nanoparticles. Thus, it expands a non-competitive parallel pathway as a supplement to the dominant formate pathway, resulting in the enhancement of Cu activity sixfold and twofold based on Cu/SiO2 and Cu/ZrO2 catalysts, respectively. The establishment of this dual-channel pathway by single-site Zr species in this work opens new horizons for understanding the role of atomically dispersed oxides in catalysis science.

Lattice-Stabilized Chromium Atoms on Ceria for N2O Synthesis

The development of selective catalysts for direct conversion of ammonia into nitrous oxide, N2O, will circumvent the conventional five-step manufacturing process and enable its wider utilization in oxidation catalysis. Deviating from commonly accepted catalyst design principles for this reaction, reliant on manganese oxide, we herein report an efficient system comprised of isolated chromium atoms (1 wt %) stabilized in the ceria lattice by coprecipitation. The latter, in contrast to a simple impregnation approach, ensures firm metal anchoring and results in stable and selective N2O production over 100 h on stream up to 79% N2O selectivity at full NH3 conversion. Raman, electron paramagnetic resonance, and in situ UV-vis spectroscopies reveal that chromium incorporation enhances the density of oxygen vacancies and the rate of their generation and healing. Accordingly, temporal analysis of products, kinetic studies, and atomistic simulations show lattice oxygen of ceria to directly participate in the reaction, establishing the cocatalytic role of the carrier. Coupled with the dynamic restructuring of chromium sites to stabilize intermediates of N2O formation, these factors enable catalytic performance on par with or exceeding benchmark systems. These findings demonstrate how nanoscale engineering can elevate a previously overlooked metal into a highly competitive catalyst for selective ammonia oxidation to N2O, paving the way toward industrial implementation.

Towards maximizing the In2O3/m-ZrO2 interfaces for CO2-to-methanol hydrogenation

Through chelating-assisted impregnation with diethylenetriamine-pentaacetic acid (DTPA), we developed an efficient and durable CO2 hydrogenation catalyst, In15/m-ZrO2-DTPA, featuring improved In2O3 reducibility and interfacial Zr-O-In structures. Benefiting from its distinct CO2 activation and hydrogenation ability, In15/m-ZrO2-DTPA exhibited remarkable CO2-to-methanol catalytic activity, achieving up to 91% selectivity at 260 °C and 5.0 MPa, with consistent conversion maintained over 400 hours.

Reaction-Induced Metal-Metal Oxide Interactions in Pd-In2 O3 /ZrO2 Catalysts Drive Selective and Stable CO2 Hydrogenation to Methanol

Ternary Pd-In2 O3 /ZrO2 catalysts exhibit technological potential for CO2 -based methanol synthesis, but developing scalable systems and comprehending complex dynamic behaviors of the active phase, promoter, and carrier are key for achieving high productivity. Here, we show that the structure of Pd-In2 O3 /ZrO2 systems prepared by wet impregnation evolves under CO2 hydrogenation conditions into a selective and stable architecture, independent of the order of addition of Pd and In phases on the zirconia carrier. Detailed operando characterization and simulations reveal a rapid restructuring driven by the metal-metal oxide interaction energetics. The proximity of InPdx alloy particles decorated by InOx layers in the resulting architecture prevents performance losses associated with Pd sintering. The findings highlight the crucial role of reaction-induced restructuring in complex CO2 hydrogenation catalysts and offer insights into the optimal integration of acid-base and redox functions for practical implementation.

Energy crisis in Europe enhances the sustainability of green chemicals

Ammonia and methanol are essential to modern societies, but their production has been heavily reliant on natural gas, which contributes to supply disruptions and significant CO2 emissions. While low-carbon or green production routes have been extensively researched, their adoption has been hindered by higher costs, making them unsustainable. However, a recent energy crisis in Europe has created a unique opportunity to shift towards greener production technologies. Here we show that, green ammonia, produced through wind-powered water electrolysis, had the potential to outperform its fossil counterpart for six months as of December 2021, while methanol produced through CO2 capture and wind-based water electrolysis became an economically appealing alternative. With a coordinated effort from academia, industry, and policymakers, Europe can lead the grand transition towards more sustainable practices in the chemical industry.

Promises of Plasmonic Antenna-Reactor Systems in Gas-Phase CO2 Photocatalysis

Sunlight-driven photocatalytic CO2 reduction provides intriguing opportunities for addressing the energy and environmental crises faced by humans. The rational combination of plasmonic antennas and active transition metal-based catalysts, known as "antenna-reactor" (AR) nanostructures, allows the simultaneous optimization of optical and catalytic performances of photocatalysts, and thus holds great promise for CO2 photocatalysis. Such design combines the favorable absorption, radiative, and photochemical properties of the plasmonic components with the great catalytic potentials and conductivities of the reactor components. In this review, recent developments of photocatalysts based on plasmonic AR systems for various gas-phase CO2 reduction reactions with emphasis on the electronic structure of plasmonic and catalytic metals, plasmon-driven catalytic pathways, and the role of AR complex in photocatalytic processes are summarized. Perspectives in terms of challenges and future research in this area are also highlighted.

Spectroscopic measurement of the two-dimensional flame temperature based on a perovskite single photodetector

Existing non-contact flame temperature measuring methods depend on complex, bulky and expensive optical instruments, which make it difficult for portable applications and high-density distributed networking monitoring. Here, we demonstrate a flame temperature imaging method based on a perovskite single photodetector. High-quality perovskite film epitaxy grows on the SiO₂/Si substrate to fabricate the photodetector. Duo to the Si/MAPbBr₃ heterojunction, the light detection wavelength is extended from 400 nm to 900 nm. Then, a perovskite single photodetector spectrometer has been developed using the deep-learning method for spectroscopic measurement of flame temperature. In the temperature test experiment, the spectral line of doping element K⁺ has been selected to measure the flame temperature. The photoresponsivity function of the wavelength was learned based on a commercial standard blackbody source. The spectral line of element K⁺ has been reconstructed using the photocurrents matrix by the regression solving photoresponsivity function. As a validation experiment, the "NUC" pattern is realized by scanning the perovskite single-pixel photodetector. Finally, the flame temperature of adulterated element K⁺ has been imaged with the error of 5%. It provides a way to develop high precision, portable, low-cost flame temperature imaging technology.

Gradient Graphdiyne Induced Copper and Oxygen Vacancies in Cu0.95 V2 O5 Anodes for Fast-Charging Lithium-Ion Batteries

Vacancies can significantly affect the performance of metal oxide materials. Here, a gradient graphdiyne (GDY) induced Cu/O-dual-vacancies abundant Cu_0.95 V₂ O₅ @GDY heterostructure material has been prepared as a competitive fast-charging anode material. Cu_0.95 V₂ O₅ self-catalyzes the growth of gradient GDY with rich alkyne-alkene complex in the inner layer and rich alkyne bonds in the outer layer, leading to the formation of Cu and O vacancies in Cu_0.95 V₂ O₅ . The synergistic effect of vacancies and gradient GDY results in the electron redistribution at the hetero-interface to drive the generation of a built-in electric field. Thus, the Li-ion transport kinetics, electrochemical reaction reversibility and Li storage sites of Cu_0.95 V₂ O₅ are greatly enhanced. The Cu_0.95 V₂ O₅ @GDY anodes show excellent fast-charging performance with high capacities and negligible capacity decay for 10 000 cycles and 20 000 cycles at extremely high current densities of 5 A g^-1 and 10 A g^-1 , respectively. Over 30 % of capacity can be delivered in 35 seconds.