If someone told you that some of the most promising materials for tackling water pollution contain elements used in electric vehicles, satellites, smartphones, and even military equipment, you might think it sounds like science fiction.
That is precisely the story of rare-earth-based perovskites, a new generation of materials attracting the attention of scientists around the world. Although few people outside the scientific community have heard of them, they could play a key role in addressing some of the major technological and environmental challenges of the 21st century [1].
Paradoxically, so-called rare earth elements are not actually that rare. The name dates back to the 18th century, when these elements were found mixed and were extremely difficult to separate.
In fact, they comprise a group of 17 chemical elements: the 15 lanthanides, along with scandium (Sc) and yttrium (Y). Among the best known are lanthanum (La), cerium (Ce), neodymium (Nd), samarium (Sm), europium (Eu) and gadolinium (Gd), which are now considered critical raw materials for the energy transition and the digital revolution.
Perovskites: What Are They?
A perovskite is a family of materials that share the same crystal structure, in which atoms or ions are arranged in a particular pattern. This structure can accommodate different chemical elements, allowing researchers to modify the material’s properties.
When elements from the rare earth group, such as lanthanum, cerium, europium or neodymium, are incorporated into a perovskite, they produce rare-earth-based perovskites whose optical, electronic, magnetic or catalytic properties can differ from those of other perovskites.
When a rare-earth-based perovskite absorbs energy from sunlight, some of its electrons become excited, triggering a series of reactions on the material’s surface.
As a result, highly reactive species such as hydroxyl radicals (•OH) and superoxide radicals (O₂•⁻) are formed. These species attack and break down industrial dyes, pesticides, pharmaceutical residues, and other organic pollutants, degrading them partially or completely into carbon dioxide, water, and other compounds with lower environmental impact [2].
The efficiency of this process depends largely on the composition of the perovskite. Incorporating rare earth elements can alter the crystal’s electronic structure, improve light absorption and promote the separation of electrical charges, reducing energy losses and increasing photocatalytic activity.
This process, known as photocatalysis, turns sunlight into a tool for removing pollutants from water more sustainably, reducing the need for chemical reagents and energy consumption compared with many conventional treatment methods.
Perovskites and Rare Earth Elements
Perovskites are a family of compounds that share a crystal architecture generally represented by the formula ABX₃. Although the structure appears simple, it is one of the most versatile in materials science.
Within this crystal structure, each site has a specific role: the A site is typically occupied by large cations; the B site by a transition metal or lanthanide; and the X site by oxygen. One of the main advantages of this architecture is that some of its elements can be replaced by others without compromising the stability of the crystal.
These changes may seem small, but they can significantly alter the material’s properties — from the way it absorbs and emits light to its ability to conduct electricity, respond to magnetic fields or participate in chemical reactions. In other words, the perovskite structure offers considerable flexibility for designing materials with specific properties.
This versatility increases when rare earth elements are incorporated into the perovskite structure, where they can change how the material interacts with light, transports electrical charges, and participates in chemical reactions.
Because of this combination of properties, rare-earth-containing perovskites are being investigated as a platform for developing materials for applications ranging from clean energy production and advanced electronics to environmental remediation [3].
We now know that rare earth elements — which, paradoxically, are not actually that rare — are distributed across different regions of the planet. However, extracting, separating, and obtaining them at the purity levels required for technological applications remains a complex and costly process [4].
Crystals That Respond to Light
Although photocatalysis is one of the most promising applications, these perovskites are also being investigated for use in next-generation solar cells, highly sensitive chemical sensors, light-emitting devices, radiation detectors, optical memory, photonic computing, green hydrogen production and advanced systems for capturing and converting carbon dioxide.
The development of new materials often goes unnoticed because it takes place inside laboratories. Yet many of the technologies that are now part of everyday life emerged from research like this — research aimed at unlocking new sources of energy and new technological possibilities, perhaps with a crystal designed atom by atom.
Key reference
López Álvarez, M. Á., Chavarín Salazar, D. I., Balderas Leon, I., & Cabrera Chavarria, J. de J. (2026). Rare-earth–based perovskite photocatalytic oxides: Fundamentals, properties and applications. IntechOpen.
Other references
- Jiang, Q., & Zhu, K. (2024). Rapid advances enabling high-performance inverted perovskite solar cells. Nature Reviews Materials, 9, 399–419.
- Rao, Z., Zhao, X., & Gong, X. (2024). Rare-earth-based lead-free halide double perovskites for light emission: Recent advances and applications. Advanced Functional Materials, 34, 2406424.
- Muhammad Humayun, Zhishan Li, Muhammad Israr, Abbas Khan, Wei Luo, Chundong Wang, and Zongping Shao. (2025). Perovskite Type ABO3 Oxides in Photocatalysis, Electrocatalysis, and Solid Oxide Fuel Cells: State of the Art and Future Prospects. Chemical Reviews 125 (6), 3165-3241. 10.1021/acs.chemrev.4c00553
- IEA (2025), Rare earth elements 2025, IEA, Paris. Rare earth elements 2025, Licence: CC BY 4.0
Author
Iván Balderas-León. Professor at Tecnológico de Monterrey’s School of Engineering and Sciences, where he has taught biopharmaceutics. He holds a PhD in biotechnology from Tecnológico de Monterrey and completed postdoctoral research at the University of Guadalajara. He has conducted scientific research projects for the pharmaceutical industry. His current research focuses on nanotechnology and nutraceuticals. He also contributes science articles to TecScience.
