Ural Federal University: Gadolinium Improved Conductivity of Hydrogen Energy Material Twenty-fold
Employees of the Institute of High Temperature Electrochemistry of the Urals Branch of the Russian Academy of Sciences and the Institute of Hydrogen Energy of Ural Federal University have created a new electrolyte material for hydrogen power. It is based on layered perovskites modified with rare-earth gadolinium, Indicator reports. Layered perovskites have good conductivity, and they can also be used to create systems that will convert the energy of chemical reactions into electricity. The development of the Ural scientists will make it possible to expand green energy technologies and thereby reduce carbon emissions. The research was supported by the Russian Science Foundation. The results of the work were published in the journal Materials.
Classical ABO3 perovskite (where A and B are two different elements and O is oxygen) is a network of octahedrons connected with each other by all vertices, and each oxygen atom is included in this network. In layered perovskites AA’BO4 octahedrons are connected in layers separated from each other by layers with a cubic structure of rock salt. It is more “flexible” than the classical perovskite, which may open up additional possibilities for its improvement.
The authors decided to modify the layered perovskites BaLaInO4 (Ba – barium, La – lanthanum, In – indium, O – oxygen) by adding atoms of the rare-earth gadolinium, which can also increase the conductivity of materials. In this case, this effect is due to the fact that the system originally had rare-earth ions – lanthanum – and the addition of their “relative” gadolinium led to more repulsion of octahedrons in the crystal lattice. As a result, the space for the transport of charged particles expanded.
The experiments showed that the modification improved the conductivity of the material in dry conditions by about 12 times (compared to the original material), and it was provided mainly by the movement of oxygen ions. In a humid environment another charge transfer mechanism was added – proton one, i.e. now the charge carriers were hydrogen ions, which is necessary for creation of hydrogen energy devices. In this case, at temperatures below 400℃, the addition of gadolinium improved the conductivity by twenty times.
“Our results suggest that modified layered perovskite could become the basis for hydrogen energy devices. We are currently working on the development of materials that could effectively combine a set of physical and chemical properties in a solid oxide fuel cell, and we plan to test them in an electrochemical device in the future. This is one of the most important tasks facing us – to make the transition from fundamental materials science to electrochemical device design, thus connecting fundamental and applied science,” says Natalia Tarasova, project leader, Doctor of Chemistry, Leading Researcher of the Laboratory of Electrochemical Devices on Solid Oxide Proton Electrolytes at the Institute of High Temperature Electrochemistry (UB RAS) and Professor at Ural Federal University.
Nowadays, gas, oil and hard coal are the main sources of energy both in Russia and abroad. However, these resources are not limitless and sooner or later will be depleted. Thus, according to estimates of the Russian Ministry of Natural Resources, in the last decade the reserves of crude oil decreased by almost 30%, and gas – by 27%. Conventional power generation based on carbon fuel also aggravates global warming by emitting large amounts of greenhouse gases into the atmosphere: last year the amount of CO2 alone was more than 36.7 billion tons.
Against the background of the growth of the Earth’s population and the environmental crisis, the development of new and improvement of existing green ways of generating energy is becoming increasingly urgent. Among them, solar energy attracts the most attention, but it is highly dependent on the angle of incidence of the rays and will not be efficient enough in the circumpolar regions, and is also not able to provide the capacity of large plants.
Another favorite is hydrogen power. It is based on the combustion of hydrogen in an oxygen atmosphere, which releases a huge amount of energy and produces water, rather than other oxides that are hazardous to people and nature, as in the case of traditional carbon energy. Although such a process is very efficient, the risks of gas explosion are high. Hydrogen energy could then be considered from another angle: in various chemical reactions, hydrogen could be used to produce protons that can be used as charge carriers in new electronic devices.