Periodic Reporting for period 1 - NACAREI (Nanofluidic Catalytic Reaction Imaging)
Periodo di rendicontazione: 2023-01-01 al 2025-06-30
To describe the context of the NACAREI project, I invoke the vision of so-called “single particle catalysis science”, which is the ability to directly correlate the activity of a single nanoparticle in the sub-10 nm size range with said nanoparticles’ surface state, structure, composition and size at operando conditions, that is, when the catalyst particle is at work at technologically relevant reaction conditions in terms of pressure, temperature and reactant concentration. This vision is driven by the prospect of unprecedented fundamental insights beyond the current research frontier in the field of heterogeneous catalysis. Such insights will provide design rules for superior catalyst materials critically needed to address some of humanity’s grand challenges and the UN goals for sustainable development in the energy, environmental clean-up and drug-development areas, for all of which catalysis is a key technology. However, at the start of the NACAREI project, such experiments and the corresponding ultimate level of insight remain unrealized, despite significant advances in the field, mainly due to the lack of experimental methods that would enable such experiments.
To fill this gap, it is the main goal of the NACAREI project to establish a novel optical nano-imaging and nano-spectroscopy experimental platform termed “Nanofluidic Catalytic Reaction Imaging” (NCRI) that for the first time will achieve a holy grail of heterogeneous catalysis by correlating – 1:1 – the activity of a single nanoparticle with its composition, structure, size, shape and support material down to sub-10 nm particles on which industrially relevant catalysis occurs.
The anticipated direct impact of NACAREI is two-fold: (i) it will provide the scientific community a novel experimental microscopy/spectroscopy platform to study catalytic reactions on single nanoparticles; (ii) it will deliver new and non-ensemble-averaged insights about the impact of widely used surfactant molecules, of catalyst nanoparticle structure/composition, and of catalyst nanoparticle support materials, on catalytic processes, to provide fundamental understanding necessary for the design of better catalyst materials.
In the more long-term, I expect impact beyond the realm of catalysis science since the developed new microscopy/spectroscopy platform also can be applied to other nanoscopic systems than catalyst nanoparticles, such as for example biological nanoparticles like lipids, extracellular vesicles or viruses and thus become of high relevance as label-free imaging/microscopy technique in the life sciences.
To fill this gap, it is the main goal of the NACAREI project to establish a novel optical nano-imaging and nano-spectroscopy experimental platform termed “Nanofluidic Catalytic Reaction Imaging” (NCRI) that for the first time will achieve a holy grail of heterogeneous catalysis by correlating – 1:1 – the activity of a single nanoparticle with its composition, structure, size, shape and support material down to sub-10 nm particles on which industrially relevant catalysis occurs.
The anticipated direct impact of NACAREI is two-fold: (i) it will provide the scientific community a novel experimental microscopy/spectroscopy platform to study catalytic reactions on single nanoparticles; (ii) it will deliver new and non-ensemble-averaged insights about the impact of widely used surfactant molecules, of catalyst nanoparticle structure/composition, and of catalyst nanoparticle support materials, on catalytic processes, to provide fundamental understanding necessary for the design of better catalyst materials.
In the more long-term, I expect impact beyond the realm of catalysis science since the developed new microscopy/spectroscopy platform also can be applied to other nanoscopic systems than catalyst nanoparticles, such as for example biological nanoparticles like lipids, extracellular vesicles or viruses and thus become of high relevance as label-free imaging/microscopy technique in the life sciences.
At the time of this periodic report, we have carried out the following activities:
• We have successfully built and started to use an experimental Nanofluidic Catalytic Reaction Imaging (NCRI) setup for liquid and gas phase single particle catalysis, and we have demonstrated both a purely imaging-based version and a spectroscopic version, where light scattered from nanofluidic channels is analyzed as function of wavelength to resolve spectral fingerprints of reactant or product molecules.
• We have demonstrated the NCRI principle for measuring refractive index changes induced upon reaction of a liquid on a single catalyst nanoparticle located in a nanofluidic structure, and thereby online and label-free derived the ToF of that nanoparticle. More specifically, we have demonstrated this twice already: (1) Using the catalytic decomposition of hydrogen peroxide on single colloidal Pt nanoparticles that we trapped inside single nanochannels using a specially developed trapping scheme. Here, we found distinct structure-induced differences between particles. Preliminary data from that study not included in the paper also revealed that ligand exchange sizably alters the activity, thereby corroborating a further key hypothesis and objective of the project, i.e. to investigate the impact of ligands on catalysis. (2) Using the catalytic reduction of fluorescein by NaBH3 on a single Au catalyst nanoparticle and the spectroscopic version of NCRI we have unraveled the complex reaction mechanism.
• We have demonstrated that it is possible to use a nanofluidic channel decorated with a single nanoparticle in combination with a quadrupole mass spectrometer and a constrained denoising auto-encoder deep learning model to measure the reaction product formed on a single nanoparticle online in the gas phase. Specifically, using CO oxidation on Pd as model reaction, we demonstrated that the catalyst surface area required for online mass spectrometry can be reduced by three orders of magnitude compared to the state of the art.
• We have developed an efficient colloidal nanoparticle trapping scheme to capture single colloidal crystals at a desired position inside a nanochannel.
Altogether, this has led to four scientific publications and the following key breakthroughs and advances:
Breakthrough 1: The successful implementation of NCRI in both imaging and spectroscopic variant, as demonstrated by two cases studies, since no method even close to what we have demonstrated has existed before and since it thereby fills a distinct gap.
Breakthrough 2: The successful demonstration of an online quadrupole mass spectrometric measurement of a catalytic reaction product formed on a single catalyst nanoparticle using a nanofluidic channel catalyst bed and a constrained denoising auto-encoder deep learning model since this demonstration reduces the active surface area required for online mass spectrometric measurements in catalysis by at least three orders of magnitude compared to the state of the art.
Advance 1: The successful demonstration of trapping of single colloidal nanoparticles inside nanofluidic channels as it will enable multiple new applications at the interface between colloidal synthesis and nanofluidics.
Advance 2: The ability to quantitatively measure solute concentrations inside nanofluidic channels with sample volumes as small as attoliters since it will make it possible to ensure that, e.g. nanofluidic operations across many fields of science do or do not influence the composition of used reactants/liquids/buffer solutions, etc.
• We have successfully built and started to use an experimental Nanofluidic Catalytic Reaction Imaging (NCRI) setup for liquid and gas phase single particle catalysis, and we have demonstrated both a purely imaging-based version and a spectroscopic version, where light scattered from nanofluidic channels is analyzed as function of wavelength to resolve spectral fingerprints of reactant or product molecules.
• We have demonstrated the NCRI principle for measuring refractive index changes induced upon reaction of a liquid on a single catalyst nanoparticle located in a nanofluidic structure, and thereby online and label-free derived the ToF of that nanoparticle. More specifically, we have demonstrated this twice already: (1) Using the catalytic decomposition of hydrogen peroxide on single colloidal Pt nanoparticles that we trapped inside single nanochannels using a specially developed trapping scheme. Here, we found distinct structure-induced differences between particles. Preliminary data from that study not included in the paper also revealed that ligand exchange sizably alters the activity, thereby corroborating a further key hypothesis and objective of the project, i.e. to investigate the impact of ligands on catalysis. (2) Using the catalytic reduction of fluorescein by NaBH3 on a single Au catalyst nanoparticle and the spectroscopic version of NCRI we have unraveled the complex reaction mechanism.
• We have demonstrated that it is possible to use a nanofluidic channel decorated with a single nanoparticle in combination with a quadrupole mass spectrometer and a constrained denoising auto-encoder deep learning model to measure the reaction product formed on a single nanoparticle online in the gas phase. Specifically, using CO oxidation on Pd as model reaction, we demonstrated that the catalyst surface area required for online mass spectrometry can be reduced by three orders of magnitude compared to the state of the art.
• We have developed an efficient colloidal nanoparticle trapping scheme to capture single colloidal crystals at a desired position inside a nanochannel.
Altogether, this has led to four scientific publications and the following key breakthroughs and advances:
Breakthrough 1: The successful implementation of NCRI in both imaging and spectroscopic variant, as demonstrated by two cases studies, since no method even close to what we have demonstrated has existed before and since it thereby fills a distinct gap.
Breakthrough 2: The successful demonstration of an online quadrupole mass spectrometric measurement of a catalytic reaction product formed on a single catalyst nanoparticle using a nanofluidic channel catalyst bed and a constrained denoising auto-encoder deep learning model since this demonstration reduces the active surface area required for online mass spectrometric measurements in catalysis by at least three orders of magnitude compared to the state of the art.
Advance 1: The successful demonstration of trapping of single colloidal nanoparticles inside nanofluidic channels as it will enable multiple new applications at the interface between colloidal synthesis and nanofluidics.
Advance 2: The ability to quantitatively measure solute concentrations inside nanofluidic channels with sample volumes as small as attoliters since it will make it possible to ensure that, e.g. nanofluidic operations across many fields of science do or do not influence the composition of used reactants/liquids/buffer solutions, etc.
The potential key impact of the results obtained so far is that microscopy, imaging and spectroscopy as introduced based on the developed NCRI platform will become an important addition to the experimental toolbox of nanoscience and nanotechnology, initially with focus on catalysis. More long-term, I anticipate that it will find application in the label-free study of other nanoscopic objects, such as biological nanoparticles in the context of life science and modern drug delivery strategies.
A second potential impact is that the obtained results will widen the applicability of nanofluidics as the developed microscopy and spectroscopy platform provides so far inaccessible information about processes inside nanofluidic channels, which, for example, may serve as model systems for nanoconfined systems in nature, such as tiny pores and vessels.
A third potential impact is that the developed microscopy, imaging and spectroscopy platform will find its way to the scientific instruments market via our startup company Envue Technologies AB and thereby rapidly becomes available to the scientific and industrial R&D community.
A second potential impact is that the obtained results will widen the applicability of nanofluidics as the developed microscopy and spectroscopy platform provides so far inaccessible information about processes inside nanofluidic channels, which, for example, may serve as model systems for nanoconfined systems in nature, such as tiny pores and vessels.
A third potential impact is that the developed microscopy, imaging and spectroscopy platform will find its way to the scientific instruments market via our startup company Envue Technologies AB and thereby rapidly becomes available to the scientific and industrial R&D community.