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Master Thesis

Then, the obtained materials will be metalated with different elements to produce a series of single atom catalysts. The main goal is to create nanoreactors comprising multiple catalytic centers that work in synergy to achieve a complex chemical transformation through tandem/cascade reaction schemes, like it happens in natural enzymes. The conversion to CO2 to valuable chemicals (hydrogenation, addition to double bonds etc) will be used as test reaction. During the thesis you will: 

o Prepare by wet chemistry the graphene derivative and assemble to create a 3D architecture o Characterize the material using a multitechnique approach (XPS, FT-IR, Raman Spectroscoy, SEM, TEM, BET etc.) 

o Test the catalytic activity of the material 

Please contact Prof. Agnoli (stefano.agnoli@unipd.it) for more information.

The main core of the set-up is an electrochemical microfluidic cell (fig. 1) where the electrolyte is confined in the cell by a thin SixNy membrane (fig.2). The membrane separates the UHV from the liquid and works as working electrode where the catalyst is deposited. It needs to be thin enough to have a good X-rays transmission, and to be conductive allowing electrochemical processes. The electrocatalyst must exhibit strong mechanical adhesion to the membrane and stability during the electrochemical reactions.

Indeed, the deposition of the electrocatalyst on the membrane required a series of optimizations, involving knowledge of nanofabrication, electrochemistry, and deposition techniques.

The candidate during the thesis work will address different issues:

• Optimization and development of the membrane.

• Electronic and chemical characterization of the developed membranes using surface science techniques, such as X-ray Photoelectron Spectroscopy (XPS).

• Morphological characterization of the membrane surface via electron microscopy, such as SEM.

• Optimization of the catalyst deposition, using different methods such as spray coating, spin coating, and drop casting.

• Testing electrocatalysis on the optimized membranes via electrochemical methods.

• Final tests in-operando conditions at the BACH beamline on the optimized membranes.

This work will be conducted in close collaboration with BACH beamline staff, Dr. Elena Magnano and Dr. Silvia Nappini.

For more information, please contact Dr. Cattelan (mattia.cattelan@unipd.it , 049-8275845).

Some of the most efficient thermionic materials exhibit negative electron affinity (NEA), a special physical feature of their electronic structure that allows an accumulation of thermalised, hot electrons in the conduction band minimum [1,2]. NEA is also important from the catalysis perspective, because it serves as a direct source of solvated electrons in water, an extremely potent reducing agent. NEA material surfaces have been used successfully as catalysts in one of the most challenging areas of photoelectrochemistry that concerns the reduction of nitrogen [3]. 

Our group facilities allow us to tackle both the physical and chemical aspects of these materials. This work will be conducted in a close collaboration with Professor Fox from University of Bristol (UK), whose research team will provide NEA diamond samples with functionalized surfaces. 

Our thesis involves:  

Be responsible of the development of a new setup to measure materials thermionic [1,2]  

• Analyses using surface science techniques, such as XPS  

• Syntheses of thermionic materials with NEA  

• Catalysis studies for nitrogen reduction [3] 

Please contact Dr Cattelan (mattia.cattelan@unipd.it) for more information.

[1] G. Wan … M. Cattelan, Adv. Funct. Mater., 2021, 31, 2007319 

[2] G. Wan, M. Cattelan et al. Carbon, 2021,185, 376 

[3] Di Zhu et. al. Nat. Mat., 2013, 12, 836 

Single atom catalysts (SACs) consist of heterogeneous metal catalysts that feature atomically dispersed metal atoms directly in the support, and are considered to bridge the gaps between homogeneous and heterogeneous catalysts. On one hand, their use allows maximizing the atomic efficiency (100%) of the metal catalysts, which often shows unexpected activity. On the other hand, it allows controlling the nature of the active sites, which helps to improve the products selectivity. 

SACs have been extensively studied in last years for electrochemical energy applications, such as the CO2 reduction reaction (CO2RR), the hydrogen and oxygen evolution reactions (HER and OER), or the oxygen reduction reaction (ORR). Many experimental and theoretical studies have shown that the M-N4 planar configuration favours these reactions. However, the large electronegativity of the symmetrical neighbouring nitrogen atoms around the metal site in the M-N4 moiety would result in unsuitable adsorption energy for the reaction intermediates, which would decrease the kinetic activity and hinder the performance.

The solution that we propose in this type of thesis is the introduction of noisy neighbours, that is, sorrounding atoms able to modify the physicochemical properties of SACs via the strong electronic coupling. In this way, we will optimize their intrinsic catalytic activity, selectivity and stability. With this aim, we propose two different types of strategies/thesis: (1) substitution of one or more nitrogen atoms by other heteroatoms with lower electronegativity (such as sulphur or phosphorus) in order to adjust the electronic structure of the active sites; or (2) addition of a second single metal atom, not only to modify the electronic structure of the active sites but, to obtain a synergetic effect between the two metals. In both cases, SACs will be dispersed and stabilized in a support material (carbon nanotubes or carbon nitride).

During the thesis you will:

o   synthetize molecular metal complexes with the desired single/dual coordination,

o   synthetize the SACs dispersed on carbon nanotubes or carbon nitride,

o   characterize the materials by XPS, XRD, EXAFS, TEM, FTIR, NMR, 

o   study the catalytic activity and selectivity toward the CO2RR, ORR, HER or OER.

Please contact Prof Calvillo (laura.calvillolamana@unipd.it) for more information.

This thesis will focus on chemical-physical analyses and catalytic behavior of “recycled” Nickel nanoparticles.

The starting materials will be provided by Circular Materials s.r.l.,[i] which developed a technology to treat wastewaters to quantitively precipitate heavy metals, with no production of sludges. Circular Materials strategy is aligned with the Circular Economy logic: it allows a full recovery of contaminating metals and convert them to secondary raw materials.

Nickel-based materials are one the most use catalysts for being cheap and available. Ni re-use it is extremely important because it is very dangerous for human health and environment. The Circular Economy of this element it is recognize as one of the most crucial point for nowadays chemistry.

You will perform a full characterization of the Ni nanoparticles using INCAT and DISC’s facilities. These include chemical-state by photoemission, morphology by electron microscopy and atomic structure by diffraction.

Catalytic tests will be the main point to set a target to the reuse these particles. Ni is used to produce “green-hydrogen” in electrolyzers, in particular for water oxidation. It is also used for water remediation to oxidize water pollutants, such as urea. You will study these reaction by electrochemical methods in semi-cell.

Please contact Dr Cattelan (mattia.cattelan@unipd.it) for more information.

[i] http://www.circularmaterials.it/