EES catalysis最新文献

The oxidative dehydrogenation (ODH) of alkanes using a solid oxide electrolysis cell (SOEC) has attracted worldwide attention as an efficient method for producing ethylene. Nevertheless, it remains challenging to achieve both a high alkane conversion rate and high ethylene selectivity. In this work, we demonstrate that the combination of doping and electrochemical activation can break this activity–selectivity seesaw and achieve a high ethylene yield. Using Sr₂Ti_0.8(Co_1.2−xFe_x)O_6−δ with different dopants as model electrodes, we show that increasing the Fe content efficiently lowers the oxygen activity by weakening metal–oxygen covalency, downshifting O 2p-band relative to the Fermi level, and increasing the oxygen vacancy formation energy. Such changes result in a lower ethane conversion rate but higher ethylene selectivity for Sr₂Ti_0.8Fe_1.2O_6−δ (STF) compared to electrodes with higher Co content. By increasing the applied potential, we can effectively increase the conversion rate of ethane without sacrificing too much ethylene selectivity. Ultimately, the SOEC with STF anode achieves an ethylene yield of up to 71% at 800 °C at 1.2 V with CO₂ as the oxidant on the cathode side, which is among the highest documented. The insights gained from this study knowledge can guide the rational design of high-temperature electrochemical devices for other small molecule conversion reactions.

The development of materials for organic solar cells has made significant strides through the strategic combination of diverse donor structures with acceptor units in polymer backbones. In contrast, semiconducting polymers for photocatalytic hydrogen evolution have primarily focused on acceptor moieties, with limited exploration of donor contributions, primarily owing to the emphasis on designing active sites for proton reduction in inorganic catalysts. To investigate the impact of highly electron-donating moieties on photocatalytic performance, we designed and synthesized benzothiadiazole (BT)-based polymers with randomly incorporated benzodithiophene (BDT) and fluorene units via a streamlined one-pot Stille–Suzuki two-step polymerization. Comprehensive molecular characterization and optical spectroscopic analyses confirmed the successful synthesis of the target polymers. Photocatalytic hydrogen evolution studies, supported by photophysical and spectroscopic investigations, demonstrated that optimizing the proportion of BDT units in the polymer backbone enhances hydrogen evolution rates significantly. Additionally, comparative analyses further highlighted the distinct differences in the photocatalytic efficiency between the BDT and fluorene donor units, providing critical insights into their functional roles. This work underscores the potential of advancing polymer photocatalysts by fine-tuning donor–acceptor interactions through optimization of donor moiety composition, offering a robust framework for achieving superior photocatalytic performance.

In this perspective we analyze copper and copper-based electrocatalysts with high ethylene selectivities from the literature to identify global catalyst formulation trends that allow for making catalysts with improved ethylene performance for industrial application. From our analysis, we identified six trends that can aid researchers in creating novel, high selectivity electrocatalysts for the electroreduction of CO₍₂₎ to ethylene. These trends were as follows. (i) Tandem-type and (ii) supported-type catalysts perform relatively more poorly than other types of systems. Engineering the nanoenvironment through implementing nanoconfining morphologies (iii) or via the addition of polymeric additives (iv) brings about significant C₂H₄ selectivity enhancements. (v) Catalyst heterogeneity is an important driver for improving C₂H₄ selectivity. (vi) Both CO₂ and CO can serve as feedstock with little impact on maximum achievable C₂H₄ selectivity. As we identified during our study that the field lacks reproducibility of catalyst performance and independent reproduction of results, we propose several strategies on how to improve. Finally, we discuss changes that authors can implement to improve the industrial relevancy of their work.

The sustainable and economic production of bio-monomer 2,5-furandicarboxylic acid (FDCA) remains a major hurdle on the path to widescale adoption of biomaterials like polyethylene furanoate (PEF). PEF offers several advantages over conventional petroleum-derived plastics, including enhanced material properties and reduced environmental impact, making its economic feasibility a significant topic of study in recent years. Overcoming the challenges of high catalyst costs, low product solubility, and reactant degradation are key to improving the viability of the process. In recent years, significant research has been reported using both noble and non-noble metal catalysts over a variety of supports including activated carbons, transition metal oxides, and other polymer- or ceramic-based materials. Additionally, heterogeneous catalysts have been investigated in aqueous, organic, and binary aqueous/organic solvent systems to address solubility concerns. In parallel, a better understanding of the reaction mechanism and impact of reaction conditions such as temperature, time, and additives have provided insight into the factors that influence FDCA production. In this review, we report the impact these factors have on 5-hydroxymethylfurfural (HMF) oxidation, with key focus on noble and non-noble catalysts in both aqueous and organic solutions. Additionally, we present mechanistic insights related to catalyst and solvent choice.

Direct electrocatalytic seawater splitting is a potential sustainable solution for large-scale green hydrogen production. However, anode deactivation due to impurities and unwanted reactions in seawater hinders its long-term performance. Here, we present a stable ionically bonded metal–organic framework/iron oxide (MOF/Fe₂O₃) heterostructured catalyst constructed via solid–liquid interfacial chemistry at room temperature. The unique M–O–M (M = metal) ionic bonds at the two-dimensional interface enhance the individual material properties, introducing additional active sites and creating facile charge flow. Theoretical calculations reveal that this system favours hydroxyl ion adsorption and inhibits the chlorine reaction, preventing corrosion and making the catalyst functional for over 900 h in complex seawater. It achieves a current density of 1 A cm⁻² at an overpotential of 410 mV, which is ∼200% higher than that of commercially used IrO₂. The heterostructured catalyst demonstrated durable performance at a higher current density of ∼1.5 A cm⁻² for more than 350 h due to selective anodic reaction and anti-corrosive behaviour against chlorine corrosion. This study provides a scalable strategy to modify the chemical states at heterointerfaces to develop robust catalysts for large-scale direct seawater splitting.

The electrochemical nitrogen (N₂) reduction reaction (eNRR) is pivotal for synthesizing green ammonia (NH₃) under ambient conditions. However, challenges such as mitigating the detrimental hydrogen evolution reaction (HER) and overcoming the sluggish proton-coupled electron transfer (PCET) step limit the efficiency of the eNRR process. Here, we present a metal–support heterostructure catalyst comprising uniform and high-density palladium nanoparticles (Pd NPs) on defective boron nitride nanotubes (D-BNNTs) via the rapid radiative Joule-heating method. Notably, the strong electronic metal–support interaction (EMSI) between the BNNT defects and Pd NPs creates an electron-deficient state in the Pd NPs, significantly reducing the PCET step and suppressing the HER. This unique configuration of the Pd NPs supported on the D-BNNT catalyst exhibits outstanding NH₃ selectivity, achieving 68.0% in neutral aqueous electrolytes and 58.9% in acidic media with a yield rate of 8.69 × 10⁻¹⁰ mol s⁻¹ cm⁻². This approach offers a strategic pathway for catalyst engineering in electrochemical reactions, presenting significant potential for practical applications.

Among direct liquid fuel cells, the direct borohydride fuel cells (DBFCs) are considered as attractive portable or mobile power sources due to their high theoretical voltage and high energy density. However, the development of DBFCs has been greatly hindered by the borohydride crossover and oxidation at the cathode. Here we have developed DBFCs featuring a borohydride-tolerant Mn–Co–C spinel cathode catalyst and a microscale bipolar interface constituting a poly(arylene piperidinium) anion exchange membrane and Nafion®-based cathode that can achieve breakthroughs in performance and scalability. The areal peak power density surpasses 2 W cm⁻² at 80 °C with a platinum loading less than 1 mg cm⁻². The three-electrode and crossover studies elucidate that the cathode polarization is significantly mitigated by the suppressed parasitic borohydride oxidation as compared with conventional configurations. The success of transforming the performance from a single cell of 1.5 × 1.5 to 5 × 5 cm² paves the way for practical applications.

In solid oxide CO₂ electrolysis cells, moderate activity and coking of the cathode are major issues that hinder commercialization of this important technology. It has been already shown that cathodes based on a mixed conducting oxide decorated with well-dispersed metal nanoparticles, which were grown via an exsolution process, are highly resilient to carbon deposition. Using perovskite-type oxides that contain reducible transition metals, such nanoparticles can be obtained in situ under sufficiently reducing conditions. However, the direct catalytic effect of exsolved metal nanoparticles on the CO₂ splitting reaction has not yet been explored thoroughly (e.g. by employing well-defined model systems), thus, an in-depth understanding is still lacking. In this study, we aim at providing a crucial piece of insight into high-temperature electrochemical CO₂ splitting on exsolution-decorated electrodes: we present the results of combined Near Ambient Pressure X-ray Photoelectron Spectroscopy (NAP-XPS) and electrochemical measurements on three different ferrite perovskites, which were employed as thin film model electrodes. The investigated materials are: La_0.6Ca_0.4FeO_3−δ (LCF), Nd_0.6Ca_0.4FeO_3−δ (NCF), and Pr_0.6Ca_0.4FeO_3−δ (PCF). The results obtained allow us to directly link the electrode's CO₂ splitting activity to their surface chemistry. Especially, the electro-catalytic activity of the materials decorated with and without metallic iron nanoparticles was in focus. Our experiments reveal that in contrast to their beneficial role in H₂O electrolysis, exsolved Fe⁰ metal particles deteriorate CO₂ electrolysis activity. This behavior contrasts with expectations derived from earlier reports on porous samples, and is likely a consequence of the differences between the CO₂ splitting and H₂O splitting mechanism.

Terpyridine (tpy) and its derivatives are strongly coordinating ligands with a high degree of customizability. Due to their tendency to form stable bis(tpy) complexes with transition metals such as Ir and Ru, their application in thermal catalysis is limited, instead revolving mostly around electro-, photo- and supramolecular chemistry. Herein, it is demonstrated that immobilization of the tpy motif via incorporation into a polymer suppresses their formation in Ir-catalyzed formic acid dehydrogenation (FADH), highlighting a distinct advantage of solid molecular catalysts (SMCs). A catalytic activity of up to 175 000 h⁻¹ was achieved at 160 °C and maintained at temperatures as low as 80 °C. Based on the results of a kinetic isotope effect (KIE) study, a catalytic cycle is proposed and the rate-determining step is identified. In a continuous setup, the most active SMC retained its activity over the course of 5 days, resulting in a TON upwards of 2 800 000. Through XPS, HAADF-STEM (-EDX) and EXAFS analyses, insights into the interaction between a metal precursor and poly-terpyridine are gained.

The emission of CO₂ and NO_x from industrial factories poses significant challenges to human health and contributes to extreme climate change. NO_x storage and reduction (NSR) and integrated CO₂ capture and methanation (ICCM) technology are some of the effective technologies used to deal with NO_x and CO₂, respectively. However, there is currently no relevant technology available for the simultaneous removal of both NO_x and CO₂ gases co-existing in flue gas. This paper proposes a new concept named CO₂/NO_x storage and reduction (CNSR) for the first time. This approach utilizes a K–Pt/Ni₃Al₁O_x dual functional material (DFM) to achieve co-storage of CO₂ and NO_x, followed by their reduction to CH₄ and N₂, respectively. The CNSR tests demonstrate the feasibility of this technology. At 350 °C, the conversion for CO₂ and NO_x was 60.8% and 99.5%, with CH₄ and N₂ selectivity of 98.9% and 90.3%, respectively. After 10 cycles, the sample exhibited a relatively stable CO₂ conversion of around 66%, with CH₄ selectivity remaining above 90%. The conversion of NO_x remained essentially unchanged at close to 100%. Furthermore, a possible mechanism for the CNSR process is proposed in this study. We believe that this work will provide a novel strategy for the treatment of multi-component gaseous pollutants in flue gas.