EES catalysis最新文献

Seawater is one of the most abundant sources of hydrogen in our environment, and it has great potential for the production of hydrogen via water electrolysis. However, seawater electrolysis is challenging as chloride ions could obstruct catalytic active sites, reducing *OH adsorption. Therefore, it is crucial to prevent chloride ions from accessing the active sites. Herein, we modulated the Lewis acidity of electrocatalysts to solve this problem. In particular, the Lewis acidity of Ni²⁺ and Fe³⁺ ions in a layered double hydroxide (LDH) was enhanced by incorporating the lanthanide dopant Ce, thereby tuning the surface electronic configurations to prefer OH* adsorption over Cl* adsorption. Further, the Ce-doped Ni–Fe LDH (CNF-LDH) was exfoliated via the O₂ plasma process to improve the accessibility of active sites for intermediates. The resultant CNF-LDH-E exhibited an overpotential of 230 and 169 mV at 100 mA cm⁻² for OER and HER, respectively, in alkaline freshwater (1 M KOH) and 290 and 285 mV, respectively, in simulated seawater (1 M KOH + 0.1 M NaCl) electrolytes. The impact of Lewis acidity on blocking the chloride ions was further investigated using density functional theory (DFT) calculations.

Hydrous iridium oxide (HIROF) is a highly active catalyst for the oxygen evolution reaction (OER) with broad application in pH sensing and charge storage devices. However, the mechanisms driving its growth, as well as the associated iridium dissolution, remain incompletely understood. To address this knowledge gap, we employ online inductively coupled plasma mass spectrometry (ICP-MS) to monitor iridium dissolution from sputtered thin films of varying thicknesses during electrochemical cycling. Complementary techniques, including atom probe tomography (APT), ellipsometry, and X-ray photoelectron spectroscopy (XPS), are used to study oxidation states and interface composition. Our findings reveal a tri-phase interface consisting of metallic iridium, compact anhydrous oxide, and hydrous oxide, where dissolution predominantly occurs at the metal–compact oxide interface, driven by transient processes during cycling. HIROF growth strongly depends on iridium grain size, with smaller grains inhibiting growth due to the accumulation of an inner compact IrO₂ layer. This effect is linked to increased oxophilicity, which lowers the reducibility of compact oxide. These insights advance understanding of HIROF growth mechanisms, offering strategies to optimize its performance and stability, particularly in proton exchange membrane water electrolyzers (PEMWEs), where iridium scarcity is critical. Broader implications extend to hydrous oxide formation on other noble and non-noble metals, potentially further advancing other electrochemical applications.

Guerbet coupling chemistry is a route to oligomerize ethanol into C₄₊ alcohols. Long chain ethers can be obtained through bimolecular dehydration of these alcohols. Ethers generated from the dehydration of C₆₊ alcohols produce a fuel that satisfies diesel engine requirements, therefore selective production of C₆₊ alcohols is of particular interest. The desired hexanol is synthesized through ethanol and butanol coupling, accompanied by the formation of undesired products through several reaction pathways. In this work the coupling of ethanol and butanol has been studied over Cu_0.01Mg_2.99AlO_x to produce C₆₊ alcohols through Guerbet coupling reactions. Two series of catalytic tests were performed at 325 °C and 300 psig by using either pure ethanol feed or a cofeed ethanol–butanol 70–30 mole%. A kinetic model was developed to predict the product distribution over a wide range of contact times. Kinetic parameters were regressed by coding a routine that included a solution of differential mole balances embedded in an optimization problem. The herein developed kinetic model was integrated in a process simulation flowsheet that models the upgrading of ethanol into C₆₊ oxygenates. The butanol cofeeding strategy in the simulations was approached by recycling the produced butanol into the coupling reactor. The simulation results reveal that cofeeding butanol into the Guerbet reactor enhances initial production rates of C₆₊ alcohols, at the expense of fostering production of byproducts from butanol self-coupling. A maximum carbon yield of 82.2% for C₆₊ diesel fuel precursors can be obtained by minimizing the byproduct production after introduction of a hydrogenation reactor.

Low-temperature plasma catalysis holds promise for electrification of energy-intensive chemical processes such as methane reforming and ammonia synthesis. However, fundamental understanding of plasma–catalyst interactions, essential for catalyst design and screening for plasma catalysts, remains largely limited. Recent work has demonstrated the importance of first-principles studies, including density functional theory (DFT), for elucidating the role of electro- and photo-effects such as electric field and charge in plasma catalysis. The availability of increasing amounts of DFT data in thermal catalysis presents a unique opportunity for plasma catalysis research to efficiently leverage this existing first-principles knowledge of thermal catalysis towards investigating plasma–catalyst interactions. To this end, this paper investigates interpretable transfer learning from thermal to plasma catalysis, with a focus on the role of surface charge. Pre-trained attention-based graph neural networks (GNNs) from the Open Catalysis Project, trained using millions of thermal catalysis DFT data points, are structurally adapted to account for surface charge effects and fine-tuned using plasma catalysis DFT data of single metal atoms on an Al₂O₃ support and adsorbates involved in plasma-catalytic ammonia synthesis. Not only does the fine-tuned attention-based GNN model provide high test accuracy for predicting adsorption energies and atomic forces in plasma catalysis, but it also exhibits adequate extrapolation for unseen single metal atoms in the plasma catalysis data used for model fine-tuning. To distinguish the effects of surface charge from other dissimilarities in DFT data of thermal and plasma catalysis, a dual-model framework is presented that relies on two pre-trained GNNs, one of which is specifically tasked to capture surface charge effects using an attention mechanism that provides interpretable insights into their role. Lastly, it is demonstrated how the attention-based GNNs developed for single metal atoms can be efficiently adapted for predicting adsorption energies and atomic forces for metal clusters in plasma catalysis. This work highlights the vast potential of interpretable transfer learning from thermal catalysis to plasma catalysis to mitigate excessive computational requirements of first-principles studies in plasma catalysis, towards accelerating fundamental research in this domain.

Engineering copper nanoparticles to achieve high dispersion and thermal stability with stable catalytic activity is crucial and challenging for the direct hydrogenation of CO₂ to oxygenates via tandem catalysis over hybridized catalysts. Herein, hybridized Cu–ZnO nanoparticles were encapsulated in nano-crystalline ZSM-5 overlayers through a steam-assisted crystallization (SAC) approach by optimizing the Cu/Zn ratios of Cu–ZnO nanoparticles, the Si/Al ratio of ZSM-5, crystalline structures, and the oxidation states of active sites to achieve higher and durable direct conversion of CO₂ into dimethyl ether (DME) and methanol. The spatially confined Cu–ZnO nanoparticles inside ZSM-5 frameworks facilitated suppressed nanoparticle aggregation by preserving major Cu⁺ phases of active copper species, which contributed to excellent catalytic performance with CO₂ conversion rate of up to 20.8% and a methanol/DME selectivity of 81.6% (DME selectivity of 62.2%) with a space-time yield (STY) of 13.9 g_DME (g_Cu⁻¹ h⁻¹). In situ DRIFTS, AES/XPS and XANES analyses further revealed that the spatial confinement effects in protective ZSM-5 zeolite overlayers effectively stabilized homogeneously dispersed Cu–ZnO nanoparticles with dominant distribution of Cu⁺ phases, which played key roles in generating formate and methoxy intermediates that are responsible for the enhanced catalytic activity and catalyst durability.

Correction for ‘High performance acidic water electrooxidation catalysed by manganese–antimony oxides promoted by secondary metals’ by Sibimol Luke et al., EES. Catal., 2023, 1, 730–741, https://doi.org/10.1039/D3EY00046J.

The performance of Ni-based oxygen evolution reaction (OER) electrocatalysts is enhanced upon Fe incorporation into the structure during the synthesis process or electrochemical Fe uptake from the electrolyte. In light of the promising potential of metal–organic framework (MOF) electrocatalysts for water splitting, Ni-MOF-74 is used as a model catalyst to study the effect of Fe incorporation from KOH electrolyte on the electrocatalyst's OER activity and stability. The insights obtained from X-ray diffraction and operando X-ray absorption spectroscopy characterization of Ni-MOF-74 and an amorphous Ni metal organic compound (Ni-MOC*) reveal that Fe uptake enhances OER by two processes: higher Ni oxidation states and enhanced flexibility of both, the electronic state and the local structure, when cycling the potential below and above the OER onset. To demonstrate the impressive OER activity and stability in Fe containing KOH, an Ni-MOC* anode was implemented in an anion exchange membrane water electrolyzer (AEM-WE) with 3 ppm Fe containing 1 M KOH electrolyte resulting in an outstanding cell voltage of 1.7 V (at an anode potential of 1.51 V) at 60 °C and 0.5 A cm⁻² exceeding 130 h of stable continuous operation.

Hydrogen peroxide (H₂O₂) is an environment-friendly oxidant with wide applications in daily life and the chemical industry. The electrochemical production of H₂O₂ through the two-electron oxygen reduction (2e⁻ ORR) process has the advantages of high safety, high energy-efficiency, and environmental sustainability. Prior investigations predominantly concentrated on the intrinsic properties of the catalysts, rather than the performance of the electrodes in real reactors. In this review, the aspects in cell design for H₂O₂ electrosynthesis will be discussed, including the surface and interface modifications for the carbon electrodes, and the reaction system design for practical H₂O₂ electrosynthesis, highlighting the critical needs in electrodes and reactors to enhance 2e⁻ ORR performance. Additionally, this review will cover the applications of 2e⁻ ORR integrated tandem systems for chemical synthesis. Finally, current challenges and prospects for future studies in H₂O₂ electrosynthesis will be presented.

Tartaric acid is an important ingredient widely used in the food, pharmaceutical, and cosmetic sectors. Over recent years, its rising industrial significance and market demand have called for more efficient and sustainable production strategies than those traditionally available. Herein, we propose bromine-mediated conversion from maleic acid—a common biomass derivative to tartaric acid. To this end, hierarchical Mo₂C nanostructures are prepared as an efficient electrocatalyst for the bromine evolution reaction at close to the theoretical potential. Bromine generated at the anode then undergoes disproportionation to HOBr, and mediates the transformation of maleic acid to epoxysuccinic acid with high selectivity, which finally hydrolyzes to tartaric acid. Our demonstrated new approach circumvents the issue of product overoxidation usually encountered with direct electrochemical oxidation, and is thereby more energy efficient and atom economic.

The rational design and synthesis of oxygen evolution reaction (OER) electrocatalysts remain critical challenges for water electrolysis in hydrogen production. This study used a strategy to activate the lattice oxygen mechanism (LOM) pathway in Co(OH)₂ through uniform co-doping with metallic Fe and nonmetallic N, thereby forming N–Co–O–Fe moieties at the Fe,N–Co(OH)_x interface. The synergistic effects of Fe and N accelerated electron redistribution from Co to Fe atoms, promoting the formation of active high-valent Co(IV) and stimulating lattice oxygen activation. The intrinsic activity of Co(OH)₂ was enhanced. The as-synthesized Fe,N–Co(OH)_x exhibited exceptional performance, with high mass activity (1705 A g_metal⁻¹) and turnover frequency (2.521  s⁻¹), surpassing those of W,N–Co(OH)_x by 80.4 and 57 times (21.2 A g_metal⁻¹ and 0.044  s⁻¹), respectively. In situ spectroscopy and ¹⁸O isotope-labeled differential electrochemical mass spectrometry confirmed that Fe,N–Co(OH)_x achieved direct intramolecular lattice oxygen coupling via the LOM pathway during the OER process. Density functional theory calculations revealed that Fe and N co-doping synergistically modulated the d-band center of Co in Fe,N–Co(OH)_x, reducing the energy barrier for OO* desorption to form oxygen vacancies. The proposed method facilitated the preparation of heteroatom-doped hydroxide catalysts to activate the LOM pathway in the OER by co-regulating multiple defects.