EES catalysis最新文献

Methanol (CH₃OH) synthesis from carbon dioxide (CO₂) hydrogenation is an industrially viable approach to CO₂ utilization. For the recently developed indium oxide (In₂O₃) catalyst, higher performance may be achieved by introducing transition metal promoters, although recent studies suggest that single atom sites favour CO formation. Here, by density functional theory-based microkinetic simulations, bulk-doped Pt/In₂O₃ single atom catalysts (SACs) with much higher CO₂ reactivity than the In₂O₃ catalyst while maintaining CH₃OH selectivity were designed. Several Pt/In₂O₃ SACs were synthesized to confirm our theoretical predictions. The synthesized Pt/In₂O₃ SAC in the predominantly bulk-doped form exhibits much higher CO₂ reactivity than the In₂O₃ catalyst with high stability and similar CH₃OH selectivity, yielding a CH₃OH productivity of 1.25 g g_cat⁻¹ h⁻¹. This study demonstrates the power of computational methods in designing oxide-based catalysts for industrial reactions and reveals a bulk-doped SAC with high performance.

Phasing out petrochemical-based thermoplastics with bio-plastics produced in an energy efficient and environmentally friendly way is of paramount interest. Among them, polylactic acid (PLA) is the flagship with its production accounting for 19% of the entire bioplastics industry. Glycerol electrolysis for producing the monomer lactic acid, while co-generating green H₂, represents a promising approach to boost the production of PLA, yet the reaction selectivity has been a bottleneck. Here, we report a combined electrochemical and chemical route using a tandem Pt/C-γ-Al₂O₃ multicomponent catalyst which can achieve a glycerol-to-lactic acid selectivity of 61.3 ± 1.2%, among the highest performance reported so far. Combining an experimental and computational mechanistic analysis, we suggest that tuning the acidic sites on the catalyst surface is crucial for shifting the reaction towards the dehydration pathway, occurring via dihydroxyacetone intermediate. Within the tandem effect, Pt is the active site to electrochemically catalyze glycerol to dihydroxyacetone and glyceraldehyde, while the γ-Al₂O₃ provides the required acidic sites for catalyzing dihydroxyacetone to the pyruvaldehyde intermediate, which will then go through Cannizzaro rearrangement, catalyzed by the OH⁻ ions to form lactic acid. This catalytic synergy improves the selectivity towards lactic acid by nearly two-fold. A selectivity descriptor (ΔG_GLAD* − ΔG_DHA*) from density functional theory calculations was identified, which could be used to screen other materials in further research. Our findings highlight the promise of tandem electrolysis in the development of strategies for selective electrochemical production of high-value commodity chemicals from low value (waste) precursors.

Correction for ‘High photocatalytic yield in the non-oxidative coupling of methane using a Pd–TiO₂ nanomembrane gas flow-through reactor’ by Victor Longo et al., EES. Catal., 2024, 2, 1164–1175, https://doi.org/10.1039/D4EY00112E.

With the continuous development and extensive research of electrocatalytic technology, the unclear dynamic catalytic reaction process limits the in-depth study of reaction regulation mechanisms and the targeted design of excellent catalysts. The comprehension of electrochemical reactions through conventional ex situ characterization techniques poses a formidable challenge. Fortunately, in situ characterization technology makes it possible to further clarify the mechanism of electrocatalytic reactions. Here, we will select some highlight studies of in situ characterization techniques during electrochemical reactions to introduce features and difficulties in practical experiments and give some advice and evaluate future development trends for relevant fields. This article will show the advantages as well as challenges in the in situ technology in electrocatalytic reactions, and indicate the development directions.

Although electrocatalytic reduction of carbon dioxide (CO₂) into chemicals and fuels over Cu-based catalysts has been extensively investigated, the influence of their exposed facets on product selectivity remains elusive. To address this, a series of Cu-based catalysts with different ratios of exposed Cu(100) and Cu(111) facets were synthesized and examined for CO₂ electroreduction, based on which a remarkable interplanar synergistic effect on the selectivity of C₂₊ products was demonstrated. The optimized Cu-based interplanar synergistic catalyst could deliver a faradaic efficiency of 78% with a C₂₊ partial current density of 663 mA cm⁻², which is extremely superior to that of its corresponding Cu counterparts with only the Cu(111) or Cu(100) facet. The interplanar synergistic effect was disclosed using density functional theory calculations to mainly benefit from favorable adsorption and activation of CO₂ into *CO on the Cu(111) facet and significantly promoted C–C coupling on the interface of the Cu(111) and Cu(100) facets, as confirmed by observation of the favorable surface coverage of atop-bound and bridge-bound *CO as well as formation of *OC–CHO intermediates during in situ infrared spectroscopy analysis.

Air plasma catalytic oxidation of toluene (C₇H₈) with the cycled storage-discharge (CSD) mode is a promising technology for toluene (C₇H₈) removal. However, the problem of low CO₂ selectivity must be solved. In this work, a novel HZSM-5 (HZ) supported Au catalyst (Au/HZ) with ca. 5.7 nm Au nanoparticles was prepared by combining impregnation-ammonia washing and plasma treatment, and adopted for C₇H₈ removal. Au/HZ displays a large breakthrough capacity and an excellent oxidation ability of C₇H₈ in dry and wet air plasma. To investigate the mechanism of CO₂ selectivity improvement with the Au/HZ catalyst, air plasma catalytic oxidation of gaseous C₇H₈ and CO, as well as the adsorption of C₇H₈ and CO on the catalysts were conducted. For plasma-catalytic oxidation of gaseous C₇H₈ over Au/HZ, the CO₂ selectivity is 97.5%, significantly higher than those of HZ (55%) and Ag/HZ (62%). In situ TPD tests indicate that Au/HZ possesses a moderate adsorption strength for CO and C₇H₈ compared with HZ and Ag/HZ. Meanwhile, plasma oxidation of CO over Au/HZ reaches 100%, which is much higher than those of HZ (15%) and Ag/HZ (24%). Nearly 100% C₇H₈ conversion and CO₂ selectivity of plasma-catalytic oxidation of C₇H₈ on Au/HZ can be attributed to the moderate adsorption strength of Au/HZ for C₇H₈ and CO, and very high plasma catalytic activity for CO oxidation.

Platinum dissolution is one of the primary factors affecting the stability of Pt-based catalysts for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). It is a significant challenge to prevent the dissolution of Pt and enhance the durability of Pt-based catalysts. In this study, we employed a one-step rapid Joule thermal shock method to fabricate a stable ORR catalyst with embedded Pt₅Ce alloy (E-Pt₅Ce). The strong catalyst-support interactions between the Pt–C layer suppress particle agglomeration and Ostwald ripening, and its steric hindrance effect reduces the electronic density at Pt sites, decreasing the adsorption energy of Pt with oxygen-containing intermediates and preventing Pt dissolution. The Pt–C layer also increases the accessibility of active sites, boosting the ORR activity. In acidic media, E-Pt₅Ce shows a mass activity (MA) and specific activity (SA) of 2.86 A mg_Pt⁻¹ and 2.03 mA cm⁻², outperforming the commercial Pt/C by factors of approximately 15 and 5, respectively. When used as a cathode catalyst for a PEMFC, the MA at 0.90 V is almost twice the DOE 2025 target. After stability testing, there is no prominent loss in catalytic activity. Density functional theory calculations confirm that the Pt–C coordination bonds also serve as reactive sites. This work uncovers the mechanism of action of the Pt–C coordination layer, which plays a crucial role in the preparation and performance of ORR catalysts.

The development of noble metal-free dye-sensitized photocatalytic systems (DSPs) for CO₂-to-CO conversion remains limited. Current literature primarily focuses on a single strategy: the simultaneous loading of both the photosensitizer (PS) and the catalyst (CAT) onto titanium dioxide nanoparticles (TiO₂ NPs) using anchoring groups. Here, we introduce an innovative method through immobilizing a positively-charged molecular CAT onto negatively-charged PS–TiO₂ NPs. Our approach yields promising results, including near-complete CO₂-to-CO conversion (∼100% CO) and exceptional stability, achieving 1658 turnover numbers versus the CAT and an apparent quantum yield efficiency (AQY) of 16.9%.

Methane is a critical energy resource but also a potent greenhouse gas, significantly contributing to global warming. To mitigate the negative effect of methane, it is meaningful to explore an effective methane conversion process motivated with green energy such as green electricity and sunlight. The selectivity and production rate are the key criteria in methane conversion. This review provides a comprehensive overview of recent efforts and understanding in methane conversion to valuable products, including oxygenates and hydrocarbons, by taking advantage of electrocatalysis and photocatalysis. The review begins with a general understanding of C–H bond activation mechanisms. It then focuses on electrocatalytic methane conversion (EMC) with an emphasis on catalyst design for oxygenate production, and photocatalytic methane conversion (PMC) with a particular focus on hydrocarbon production, especially ethylene (C₂H₄), due to the differences in oxygen sources between the two systems. An in-depth understanding of EMC and PMC mechanisms is also discussed to provide insights for improved catalyst design aimed at selective product generation. Finally, successful catalyst designs for EMC and PMC are summarized to identify challenges in achieving highly efficient and selective production of value-added chemicals and to offer clear guidance for future research efforts in green methane conversion.

Catalytic fast pyrolysis (CFP) of biomass is an efficient approach that can overcome the structural recalcitrance of solid biomass (e.g., crystalline cellulose) to produce sugar monomers and their derivatives within seconds. The composition of the product mixture, which is accumulated in a liquid called bio-oil, is highly tuneable through the use of in situ/ex situ catalysts for the downstream production of sustainable fuels and fine chemicals. This minireview summarises the recent advances in homogeneous and heterogeneous catalysts in the CFP production of versatile oxygenates as fuel precursors or bulk chemicals. First, a brief overview of primary CFP pathways, including cellulose-to-levoglucosan (LGA) conversion and the production of three important derivative anhydrosugars, is provided. Particular attention is paid to the roles of homogeneous and heterogeneous catalysts in promoting secondary reforming of LGA by dehydration and to alternative pathways via C3–C6 cyclisation or benzylic rearrangement over versatile catalysts (e.g., aqueous acids, zeolites, metal oxides) with Brønsted/Lewis acidity to produce a variety of oxygenates in bio-oil. This minireview may provoke more CFP technologies by clarifying the opportunities and challenges in the selective production of different reformed oxygenates, complementing CFP-based production of aromatics from biomass.