Friday, 01 July 2022

Materials for hydrogen photoproduction and CO2 reduction

The latest news about the Departments of Excellence Project – FLEXILAB

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The exploitation of fossil fuels had and continues to have deleterious effects on our ecosystem. Abandoning them as soon as possible and pursuing increasingly cleaner ways of producing energy would be a great way to ensure a sustainable future for our civilization. Hydrogen represents one of the solutions for decarbonising the planet and finds applications in many areas: in the industry (as a raw material and energy production), in clean transport, in residential (energy, heating), in generation and storage of electricity.

One of the five research topics addressed by the FLEXILAB Project, "Departments of Excellence" project 2018-2022 concerns precisely the clean production of hydrogen and the reduction of CO2.

We interviewed Prof. Norberto Manfredi, professor of Organic Chemistry at the Department of Materials Science and work package leader of this research activity, to understand what the potential of hydrogen is and what were the results achieved during the project.

Why is hydrogen a clean energy source?

Actually, hydrogen is not an energy source but an energy carrier. Hydrogen is undoubtedly the main fuel to push the energy transition towards decarbonisation. In fact, its combustion generates only water vapour and can be used to produce important chemical compounds from the recovery of CO2. However, at the moment more than 90% of the hydrogen produced is obtained by steam reforming of methane, producing CO2 as a by-product. This process has a negative impact on the environment and given the current socio-political conditions, puts our country in a complicated situation, having to purchase raw materials and then transform them without any advantage for the environment. Hydrogen will be a clean fuel only when it is produced in a clean way, without CO2 production.

Which is the goal of this research activity?

In accordance with what has been said, the objective of this part of the project is to design and manufacture materials to be used in devices for the direct production of hydrogen from water and sunlight. Similarly, considering the more direct usability of carbon-based fuels, materials and devices will also be developed capable of converting CO2 into fuels (methane, methanol) or chemicals of synthetic interest (carbon monoxide, formaldehyde, formic acid).

What were the results achieved?

In recent years, the activities have developed along three interconnected lines of research. The activities have developed organic materials, inorganic materials and their integration into photocatalytic or photoelectrochemical devices for the production of hydrogen or solar fuels.

In the field of organic materials, four different series of organic dyes have been developed for artificial photosynthesis and have been studied in photocatalytic hydrogen production processes or photoelectrochemical processes for the photo-oxidation of water and photo-reduction of protons to hydrogen and CO2 to solar fuels (methanol, methane) and products of chemical interest (carbon monoxide, formaldehyde, and formic acid).

Approaches compatible with the dictates of green chemistry have been developed for the preparation of p-type organic semiconductors for photocatalytic hydrogen production. In parallel, compounds structurally related to the DMBI derivative were developed that could be used for the reactive storage of hydrogen directly in aqueous dispersion.

In the field of inorganic materials, powder samples of glass-ceramic systems containing wide-gap oxide nanoparticles were prepared. In particular a first screening was made to test the photocatalytic properties thanks to degradation measurements of organic molecules under UV irradiation and now are under investigation for the production of hydrogen.