Formed from an organic linker and a metal salt cluster, Metal Organic Frameworks (MOFs) are highly crystalline materials with a large surface area, pore size and pore volume. Some of these MOFs show a step-wise water adsorption behaviour. This would make them suitable for seasonal thermal heat storage through water adsorption, due to their high stability in a moist air environment and a relatively large adsorption capacity. This thesis is dedicated to modelling MIL-101(Cr), MIL-100(Fe), Aluminium fumarate, MOF-841(Zr), CAU-10(Al)-H, MIL-125(Ti)-NH2, MIL-160(Al) and CPO-27(Ni). The adsorption capacity was tested using two situations with a different set of temperatures. From these MOFs, three of the better performing MOFs were eventually tested, to measure the water adsorption energy density. With this data, the expected needed storage volume of the MOF was estimated, where the best MOF was chosen.

Owing to global warming and fast depleting fossil reserves, the world is currently witnessing an energy transition into cleaner and greener energy sources like the wind and solar energy. At present, most of this clean energy is converted into electricity and used up directly or stored in the grids or batteries to be used later. Chemical storage of this energy is an attractive alternative due of its high energy density. Artificial photosynthesis is a hot field wherein researchers try to mimic the photosynthesis process of plants and try to convert solar energy into chemicals that can be stored. Photo-electrochemical (PEC) water splitting is one such pathway that is extensively investigated. However, the ideal semiconductor required to make this conversion efficient and economical is yet to be discovered. A big share of research also focuses on materials or techniques to improve the performance of these PEC devices independent of the semiconductor. Plasmonics, or plasmonic hot electron injection in particular, is such a technique that is being extensively investigated. Plasmonic hot electron injection is a relatively new phenomenon that could have potential application in many fields including photo-electrochemistry and photovoltaics. It is coveted as one of the techniques that could directly improve the performance efficiencies of solar and photo-electrochemical cells. But a fundamental understanding of this phenomenon is still lacking. This is crucial for improving and optimizing this technology before it can have any practical application. In this thesis, photo-electrochemistry is used as a tool to study the plasmonic hot electron injection and shed more light on the fundamental aspects, at the nanoscale, involved in the excitation and injection of hot electrons into the conduction band of a semiconductor. Silver, gold and 50% silver – 50% gold alloy nanoparticles are used in this work to systematically
study the effect of composition, size and concentration of these nanoparticles on the hot electron injection efficiency. Through this work, some fundamental understanding of the factors affecting the energy of the excited hot electron and hot electron injection process is obtained.

A major challenge in nanotechnology is that of determining how to introduce green principles when assembling individual nanoscale elements to create multifunctional working devices. This dissertation focuses on fundamentals (Part A), scaling-up (Part B) and application (Part C) of nanoparticles with sub-10 nm in size produced by ambient spark ablation, which is a scalable and environmentally benign process, providing great versatility in producing inorganic nanoparticles consisting of a wide variety of conducting or semiconducting materials with virtually unlimited mixing possibilities. In Part A, a new ‘singlet’ concept has been introduced, which rules out the pseudo-paradigm: continuous gas-phase synthesis of nanoparticles is associated with rapid agglomeration. Subsequently, a general approach has been developed to describe the size distributions of singlet particles as a function of the process conditions. In Part B, a newly developed high-frequency spark yields a series of monometallic and bimetallic nanoparticles, sub-10 nm (primary) particles and well-defined chemical composition, providing a green and versatile platform for manufacturing key building blocks toward industrial scale. To improve the uniformity of nanoparticles, inhibition of ‘splashing’ particles (larger than 100 nm) has been successfully achieved by using an external magnetic field within the inter-electrode gap. The resulting Lorenz force deflects the continuous glowing current, onto which sparks are superimposed, thereby avoiding the sparks to strike the same point of electrode surface. To explore internal nanoparticle mixing, a model developed here links the composition of nanoparticles to spark oscillations. In Part C, by integrating gas-phase nanoparticle syntheses into textile nanofinishing, a number of constraints encountered in traditional wet-finishing processes, can be circumvented while creating a new class of fabrics. As proof of this concept, Ag nanoparticles are deposited onto a range of textiles, imparting high antimicrobial activities and exhibiting good washing durability. Accounting for the green, scalability and versatility of the technique used here as well as its compatibility with the existing fabrication processes, the generated nanoparticles bear a great potential for creating multifunctional working devices.

Nanomaterials are a growing source for innovation. However, the very properties that make them so effective for their desired purpose might also render them more hazardous towards humans and the environment. Adequate risk assessment tools are often missing, partly due to instrumental gaps in exposure assessment and toxicity testing. In this thesis, two of these instrumental gaps served as the motivation to develop two new instruments, both with the purpose to reduce these gaps. The nano-PMC is a Particle Mass Classifier that is able to directly measure the mass of single particles down to a few zeptograms. Information about nanoparticle mass is vital for converting nanoparticle number concentrations to mass concentrations, a metric which is very useful for exposure assessment. In combination with mobility classification, the so-called apparent density of non-spherical particles like agglomerates can be measured, a property that might determine the health effect of non-toxic but biopersistent dust particles. The Cyto-TP is a thermal precipitator that deposits airborne nanoparticles onto living cells. Both the exposure mode and the cell configuration are designed to mimic the contamination of the pulmonary alveoli to inhaled nanoparticles. This instrument, as part of an in vitro inhalation toxicity test, might contribute to the reduction of the need for animal testing. Both instruments find application within a proposed test procedure to assess the risk potential of nanomaterials still in development - to promote safety-by-design. This precautionary approach might help to increase public confidence in nanomaterials.