E01-JEM ARM 200CF
E02-JEM ARM 300CF
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Diamond Proposal Number(s):
[37092]
Open Access
Abstract: Decoherence in superconducting quantum circuits, caused by loss mechanisms like material imperfections and two-level system (TLS) defects, remains a major obstacle to improving the performance of quantum devices. In this work, we present atomic-level characterization of cross-sections of a Josephson junction and a spiral resonator to assess the quality of critical interfaces. Employing scanning transmission electron microscopy (STEM) combined with energy-dispersive X-ray spectroscopy (EDS) and electron-energy loss spectroscopy (EELS), we identify structural imperfections associated with oxide layer formation and carbon-based contamination, and correlate these imperfections to the pattering and etching steps in the fabrication process and environmental exposure. These results help to understand that TLS imperfections at critical interfaces play a key role in limiting device performance, emphasizing the need for an improved fabrication process.
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Jul 2025
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E02-JEM ARM 300CF
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Diamond Proposal Number(s):
[35687]
Abstract: Over the past decade, hybrid nanomaterials have emerged as a key area of research due to their ability to combine multiple functionalities within a single nanoscale system. Among these, core@shell heterostructures, especially those integrating noble metals with functional coordination polymers, offer promising properties and synergistic effects for applications in catalysis, magnetism, and biomedicine. This doctoral thesis focuses on the development of hybrid nanoparticles consisting of a gold (Au) core and a Prussian Blue Analogue (PBA) shell, aiming to investigate the synergistic properties arising from their unique hybrid structure. PBAs are coordination polymers with a cubic lattice and a highly tunable structure. Their open lattice structure allows modifications in the chemical composition, enabling the fine-tuning of their magnetic, catalytic, and electrochemical properties. Additionally, their ability to host ions and molecules makes them particularly attractive for biomedical applications. To improve the efficiency of PBAs in specific fields, it is often necessary to enhance their intrinsic properties or introduce new functionalities. In this regard, combining PBAs with Au nanoparticles has proven to be a highly effective strategy. Gold nanoparticles offer excellent chemical stability, unique optical behavior, precise control over size and shape, and broad application potential. Their integration with PBAs not only improves thermal and electrical conductivity but also introduces additional optical effects through localized surface plasmon resonance (LSPR), expanding their functional scope. However, synthesizing Au@PBA nanostructures poses significant challenges due to the reactivity of gold with cyanide, a key component in PBA formation. To overcome this, the thesis presents an optimized protocol based on colloidal chemistry that permits the stable obtention of Au@PBA nanoparticles. The work is organized into four chapters. Chapter 1 introduces the fundamental concepts of PBAs and Au nanoparticles, with an emphasis on their role in advanced hybrid nanomaterials and the advantages of core@shell. Chapter 2 outlines the synthesis and characterization of Au@CsNiFe nanoparticles, developed using Au nanoparticles functionalized with 4-mercaptopyridine (4-MPy) to guide the controlled growth of the PBA shell. These hybrid particles show enhanced electrocatalytic activity in the oxygen evolution reaction (OER), which is directly influenced by the shape architectures (spheres, rods and stars) and size of the gold core. Chapter 3 investigates the photomagnetic behavior of Au@CsCoFe nanoparticles. By varying the PBA shell thickness, it is shown that photomagnetic activity increases due to a higher concentration of photo-responsive species. Furthermore, the removal of the Au core yields hollow nanostructures with altered magnetic properties, underscoring the significant role of chemical morphology in determining functionality. Chapter 4 explores the biomedical application of Au@CsMnFe nanoparticles. These nanoparticles demonstrate high colloidal stability in physiological media and are capable of controlled drug release. The introduction of an internal cavity (yolk@shell configuration) significantly improves drug loading and release efficiency. Furthermore, under near-infrared (NIR) irradiation, the nanoparticles exhibit a strong photothermal response, making them suitable candidates for photothermal therapy (PTT). In conclusion, this thesis establishes effective synthesis methods for fabricating multifunctional Au@PBAcore@shell nanostructures, paving the way for application-specific nanoplatforms. The developed materials demonstrate tunable performance across three domains: catalytic activity (CsNiFe), photomagnetic behavior (CsCoFe), and therapeutic efficiency (CsMnFe).
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Jun 2025
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B18-Core EXAFS
E02-JEM ARM 300CF
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Abstract: Catalytic hydrogenation reactions represent one of the most important transformations in the chemical industry. In the light of the required defossilization of the chemical value chain, the development of new, highly selective hydrogenation catalysts is of utmost importance to deal with renewable resources, such as biomass, recycled feedstock, or CO2. In that regard, this thesis deals with the preparation, characterization and application of metal nanoparticles (NPs) on molecularly modified surfaces for thermo- and electrocatalytic hydrogenation reactions. In the thermocatalytic systems, Mn-based NPs are investigated (monometallic and bimetallic MnRu NPs), as this earth-abundant metal possesses a low environmental impact and generally low toxicity. In addition, the electrocatalytic hydrogenation of alkenes, aldehydes and ketones using a Pickering emulsion-based system is described. Here, Pd NPs on molecularly modified carbon nanotubes are evaluated as catalyst. Firstly, small (1-10 nm) Mn NPs are immobilized on different carbon-based supports, as well as on a supported ionic liquid phase (SILP). Different synthetic methods are developed in order to optimize the properties of the NPs on each respective support, which are investigated using various characterization methods. The materials are evaluated for different catalytic transformations, with the catalytic transfer hydrogenation of aldehydes and ketones using Mn@SILP being found to be best performing. This material is demonstrated to be more active than previously reported Mn NP-based systems. X-ray absorption studies showed that the catalytic activity is highly dependent on the oxidation state of Mn. Followingly, bimetallic MnRu@SILP materials are prepared and characterized. Tuning the metal ratio of Mn:Ru enables the selective targeting of different products for substrates containing multiple reducible moieties. Furthermore, the alloying state of these NPs is investigated in order to assess its importance for the performance of the catalysts. The last part of this thesis deals with electrocatalytic hydrogenation (ECH) reactions, which offer an attractive way for the use of renewable electricity for chemical transformations. As water is used as solvent and hydrogen donor, the application of this reaction type for the conversion of apolar, organic systems is rather limited. In order to overcome this challenge, a Pickering emulsion-based system is developed. Herein, the apolar substrates are located within oil droplets, which are surrounded by an aqueous phase, providing the protons and high conductivity. This emulsion is stabilized by Pd NPs on molecularly modified CNTs. These CNTs additionally conduct electricity to the interface where the reaction is catalyzed by the Pd NPs. The mechanism of the ECH of alkenes is investigated and the reaction rate and Faradaic efficiency surpassed state-of-the-art Pd membrane reactors. The ECH system is further extended to the ECH of aldehydes and ketones to the respective alcohols. Here, the subsequent deoxygenation products can be also be yielded, which was not demonstrated yet in the electrocatalytic application of Pd NPs. Overall, this work contributes towards the development of novel catalytic systems for selective hydrogenation reactions. It can be demonstrated that metal NPs on molecularly modified surfaces represent a class of highly tunable catalysts. Their NP composition, choice of support and molecular modifier are varied to design highly efficient and selective catalysts for thermo- and electrocatalytic hydrogenation reactions.
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Jun 2025
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B18-Core EXAFS
E02-JEM ARM 300CF
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Diamond Proposal Number(s):
[34632]
Open Access
Abstract: Conventional catalytic CO2 reduction into value-added products often encounters challenges such as high energy barriers and complex operational setups. Here, we introduce a sonocatalysis approach to CO2 reduction in water under ambient conditions. In an acoustic cavitation-induced high-energy local environment, the Cu nanoparticles incorporated on the ZnAl-layered double oxide create a favorable energy barrier for CO2 reduction in water, a CO production rate of 23.8 μmolCO g−1 h−1 with over 85% selectivity was achieved by ultrasonic irradiation of a CO2-saturated aqueous solution at room temperature. Furthermore, more acoustic cavitation was produced with 5% CO2 in argon dissolved in water, resulting in a higher CO productivity of 252.7 μmolCO g−1 h−1, 11 times larger than pure CO2. Hydrogen production also increased with acoustic cavitation, creating a syngas mixture with a CO to H2 ratio of 1.2 to 2.2. This approach produces a high sonochemical efficiency of 211.1 μmol kJ−1 g−1 L−1 for the ultrasound-driven fuel production from CO2 and water. These results highlight the use of cavitation to provide an alternative approach to CO2 conversion.
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May 2025
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E02-JEM ARM 300CF
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Open Access
Abstract: Aqueous zinc-ion batteries (AZIBs) are increasingly seen as promising options for stationary energy storage, given their high volumetric capacity, intrinsic safety, and affordability. To enable their widespread adoption for large-scale applications, improvements in AZIB performance and stability, particularly in cathode materials like MnO2, are essential. Enhancing cathode properties—specifically achieving high-loading, high-capacity, and high-stability—is critical for AZIBs industrialization. High-loading cathodes accommodate more active material per unit area, increasing energy density and reducing the battery's footprint. High-capacity cathodes store more energy per unit mass or volume, crucial for applications requiring long-duration energy storage, such as grid-level energy balancing. Moreover, high-stability cathodes ensure long-term performance and reliability, crucial for industrial environments where downtime is costly. Nevertheless, with the escalation of unit mass loading, the dynamics of electron and ion transport within the electrode diminish, significantly impacting both capacity and cycle stability. This phenomenon is commonly referred to as the "Trilemma" in battery technology. This thesis proposes a decoupling enhancement strategy for surface and bulk materials to achieve these cathode properties simultaneously, advancing AZIBs industrialization. By focusing on electron and ion transport dynamics in Mn-based cathodes of AZIBs, the research develops a high-loading cathode based on designs of electrode structure (free-standing three-dimensional network), material property (double-ion pre-intercalation), fabrication process design (slurry treatment), facilitating high-loading cathode applications in Ah-level full cells. The study employs physicochemical and electrochemical characterizations, along with ex-situ material characterization and computational simulations, to elucidate cathode engineering details. Overall, this research aims to address critical factors in AZIBs development, laying the groundwork for their widespread industrial use in energy storage applications. The PhD project encompasses three primary works, outlined below: (1) MnO2-based cathodes in AZIBs offer stability and safety yet face challenges in slow kinetics due to low electrical conductivity, crucial for rapid charging devices. Addressing these hurdles, a sodium-intercalated manganese oxide (NMO) with 3D varying thinness carbon nanotubes (VTCNTs) network is proposed as a binder-free cathode (NMO/VTCNTs) without heat treatment. This novel network, utilizing low-thinness CNTs (LTCNTs) and high-thinness CNTs (HTCNTs), enhances specific capacity and mass loading. The interconnected CNTs withstand deformation, providing extra Zn2+ storage and efficient ion/electron migration routes. The NMO is evenly distributed within CNTs, improving structural stability and transport rates. The cathodes achieve loading of 5 mg cm−2, retaining high specific capacities of 329 mAh g−1 after 120 cycles at 0.2 A g−1, 225 mAh g−1 after 200 cycles at 1 A g−1, and 158 mAh g−1 after 1000 cycles at 2 A g−1. This construction strategy offers insights into achieving high mass loading and capacity, presenting significant potential for industrial application. (2) This study introduces a dual-ion co-intercalation strategy to enhance Mn-based cathodes in AZIBs. By incorporating both sodium and copper ions into δ-MnO2 (NCMO), stable cycling performance and high specific capacity are simultaneously achieved, even under high mass loading. Pre-intercalated Na+ boosts the Cu2+-driven activation of the Mn2+/Mn4+ redox process, while the smaller ionic radius of Cu2+ accelerates diffusion for improved charge/discharge kinetics. At lower mass loadings, the synergistic action of Na+ and Cu2+ sustains a prolonged capacity enhancement, whereas at higher loadings it enables a reversible Mn deposition/dissolution process.
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May 2025
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E02-JEM ARM 300CF
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Emanuele
Telari
,
Antonio
Tinti
,
Manoj
Settem
,
Carlo
Guardiani
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Lakshmi Kumar
Kunche
,
Morgan
Rees
,
Henry
Hoddinott
,
Malcolm
Dearg
,
Bernd
Von Issendorff
,
Georg
Held
,
Thomas
Slater
,
Richard E.
Palmer
,
Luca
Maragliano
,
Riccardo
Ferrando
,
Alberto
Giacomello
Diamond Proposal Number(s):
[28449]
Open Access
Abstract: Finding proper collective variables for complex systems and processes is one of the most challenging tasks in simulations, which limits the interpretation of experimental and sim- ulated data and the application of enhanced sampling techniques. Here, we propose a machine learning approach able to distill few, physically relevant variables by associating instantaneous configurations of the system to their corresponding inherent structures as defined in liquids theory. We apply this approach to the challenging case of structural tran- sitions in nanoclusters, managing to characterize and explore the structural complexity of
an experimentally relevant system constituted by 147 gold atoms. Our inherent-structure variables are shown to be e!ective at computing complex free-energy landscapes, transi-
tion rates, and at describing non-equilibrium melting and freezing processes. In addition,
we illustrate the generality of this machine learning strategy by deploying it to understand conformational rearrangements of the bradykinin peptide, indicating its applicability to a vast range of systems, including liquids, glasses, and proteins.
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May 2025
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E02-JEM ARM 300CF
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Diamond Proposal Number(s):
[35866]
Open Access
Abstract: The catalytic hydrogenation of amides with molecular hydrogen (H2) is an appealing route for the synthesis of valuable amines entering in the preparation of countless organic compounds. Running effective amide hydrogenation under mild H2 pressures is challenging although desirable to preclude the need for specialized high-pressure technologies in research and industry. Here we show that magnetocatalysis with standard supported catalysts enables unprecedented amide hydrogenation at mild conditions. Widely available and commercial platinum on alumina (Pt/Al2O3) was functionalized with iron carbide nanoparticles (ICNPs) to allow for localized and rapid magnetic induction heating resulting in the activation of neighboring Pt sites by thermal energy transfer. Exposure of the ICNPs@Pt/Al2O3 catalyst to an alternating current magnetic field enables highly active and selective hydrogenation of a range of amides at a reactor temperature of 150 °C under 3 bar or even ambient pressure of H2. ICNPs@Pt/Al2O3 reacts adaptively to fluctuations in electricity supply mimicking the use of intermittent renewable energy sources. This work may pave the way toward a greatly enhanced practicability of amide hydrogenation at the laboratory and production scales, and demonstrates more generally the broad potential of the emerging field of magnetocatalysis for synthetic chemistry.
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Apr 2025
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E02-JEM ARM 300CF
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Diamond Proposal Number(s):
[30716, 33118, 40768]
Open Access
Abstract: Extensive research has been conducted on carbon-supported single-atom catalysts (SACs) for electrochemical applications, owing to their outstanding conductivity and high metal atom utilization. The atomic dispersion of active sites provides an ideal platform to investigate the structure-performance correlations. Despite this, the development of straightforward and scalable synthesis methods, along with the tracking of the dynamic active sites under catalytic conditions, remains a significant challenge. Herein, we introduce a biomass-inspired coordination confinement strategy to construct a series of carbon-supported SACs, incorporating various metal elements, such as Fe, Co, Ni. We have systematically characterized their electronic and geometric structure using various spectroscopic and microscopic techniques. Through in situ X-ray absorption spectroscopy (XAS) and atomic scanning transmission electron microscopy (STEM) and electron paramagnetic resonance (EPR) analyses, it is demonstrated that the single atoms undergo structural rearrangement to form amorphous (oxy)hydroxide clusters during oxygen evolution reaction (OER), where the newly formed oxygen-bridged dual metal M-O-M or M-O-M’ (M/M’=Fe, Co, Ni) moieties within these clusters play key role in the OER performance. This work provides essential insights into tracking the actual active sites of SACs during electrochemical OER.
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Apr 2025
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E02-JEM ARM 300CF
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Diamond Proposal Number(s):
[28500, 30057, 30160, 30157, 31872]
Open Access
Abstract: Organic molecular crystals encompass a vast range of materials from pharmaceuticals to organic optoelectronics, proteins and waxes in biological and industrial settings. Crystal defects from grain boundaries to dislocations are known to play key roles in mechanisms of growth1,2 and in the functional properties of molecular crystals3,4,5. In contrast to the precise analysis of individual defects in metals, ceramics and inorganic semiconductors enabled by electron microscopy, substantially greater ambiguity remains in the experimental determination of individual dislocation character and slip systems in molecular materials3. In large part, nanoscale dislocation analysis in molecular crystals has been hindered by the low electron doses required to avoid irreversibly degrading these crystals6. Here we present a low-dose, single-exposure approach enabling nanometre-resolved analysis of individual dislocations in molecular crystals. We demonstrate the approach for a range of crystal types to reveal dislocation character and operative slip systems unambiguously.
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Mar 2025
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E02-JEM ARM 300CF
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Diamond Proposal Number(s):
[35687]
Open Access
Abstract: Au@Prussian-Blue analogue (PBA) core@shell nanoparticles (NPs) are highly versatile nanostructures with complementary and shape-dependent properties of interest in the current technologies. However, due to the high reactivity of cyanides toward Au, scarce PBAs have been successfully synthesized in direct contact with Au NPs, leaving the formation of anisotropic Au@PBA NPs as a significant synthetic challenge. Here, we have developed a robust protocol for synthesizing core@shell NPs, composed of a magnetic CsNi[Fe(CN)6] PBA shell grown on individual Au NPs, regardless of the core morphology (spheres, rods, or stars). Specifically, the uniqueness of our protocol lies in the prior Au core functionalization with anchoring molecules that facilitate PBA growth while preventing Au etching and preserving the initial oxidation states of the metals. This has afforded direct growth of ferromagnetic NiIIFeIII PBAs on Au NPs. Moreover, by exploiting the structural mismatch at the Au/PBA interface and the curvature of anisotropic Au templates, we manage to induce a substantial structural strain within the PBA shell. When star-shaped Au nanoparticles are used, a maximum strain of 2.0% is reached. This strain combined with an increased polycrystallinity lead to modifications in the PBA catalytic properties, resulting in a 10-fold improvement in the intrinsic electrocatalytic activity.
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Mar 2025
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