Pyroelectrocatalysis for Hydrogen Production?

Pyroelectricity is used, for example, in pyrosensors, which are sensitive to thermal radiation. A team of researchers has now found, how the phenomenon can also be used for chemical reactions.

Pyroelectricity is a physics phenomenon that, like piezoelectricity, has long been used in sensors. Piezoelectricity describes the change in electrical polarization and the associated occurrence of an electrical charge on solids during directed elastic deformation. Conversely, the application of an electrical voltage produces an elastic deformation of the crystal. Pyroelectricity can be understood as a parallel phenomenon to piezoelectricity: "The heating of certain crystals (e.g. tourmaline, scolecite) leads to the unequal (polar) occurrence of electrical charges. When cooling down, the polarity is reversed".

If certain materials are deformed by the action of external forces or pressures, an electrical voltage is created, and the force or pressure shifts the charges inside the material.

Now its gets a bit special in wording. "All pyroelectric materials also show the piezoelectric effect, but not all piezoelectric materials show the pyroelectric effect", which summarize in the book chapter "Physical Effects on Sensor Use". If piezoelectricity is used to determine quantities such as force, torque, pressure, acceleration or vibration, pyrosensors react particularly sensitively to changes in radiation intensity over time and space. "Preferred areas of use are therefore motion or fire alarms".

A team of physicists from the TU Bergakademie Freiberg has now found a way to use the voltage generated on the surfaces of pyroelectric materials for chemical reactions, for example for converting waste heat into hydrogen. The Freiberg scientists succeeded in describing and predicting the catalytic processes on pyroelectric surfaces in a model. The researchers have published their results in the journal "Physical Chemistry Chemical Physics". "The splitting of water into oxygen and hydrogen, which is a popular gas as an energy source and in the chemical industry, is particularly interesting," says Mateo de Vivanco, first author of the study.

This means voltage can be used for chemical reactions. Even though this reaction could already be proven experimentally a few years ago, the physico-chemical background has still remained largely in the dark. This is where the Freiberg team came in: "As a chemist in a physical work group, I wanted to calculate the water splitting yield. Since this was not possible with existing models, my team and I considered which factors could limit the pyroelectric yield," says the first author of the study . Compared to the direct use of electricity, one has to cope with overvoltage’s of different types in the hydrogen production, which could hinder the splitting of water. After several years of research, it was finally possible to develop the now presented chemical-physical model with which the processes on pyroelectric surfaces in chemically labile media, such as water, can be explained and predicted.

I know its a bit geeky, but such studies proof and show that there is still a lot to gain with hayxdrogen energy and its now the right time ton shift resources into that technology to fit as much as possible the climate changes.

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