London Irvine Report

New two-dimensional material could revolutionize solar fuel generation

Publicado em 30 julho 2018

Source: Fundação de Amparo à Pesquisa do Estado de São Paulo

Summary: Scientists have obtained from hematite a new material with application as a photocatalyst, christened 'hematene.' The three-atom thick hematene is a ferromagnetic material, as opposed to the iron ore from which it was created.

Following the isolation of graphene in 2004, a race began to synthesize new two-dimensional materials. 2D materials are single-layer substances with a thickness of between one atom and a few nanometers (billionths of a meter). They have unique properties linked to their reduced dimensionality and play a key role in the development of nanotechnology and nanoengineering.

An international group of researchers including Brazilian scientists affiliated with the University of Campinas (UNICAMP) have succeeded in producing a new material with these characteristics.

The researchers extracted a 2D material they call hematene from ordinary iron ore like that mined in many parts of the world, including Brazil. The material is only three atoms thick and is thought to have enhanced photocatalytic properties.

The innovation is described in an article published in Nature Nanotechnology. The research was conducted at the Center for Computational Engineering and Sciences (CCES), one of the Research, Innovation and Dissemination Centers (RIDCs) funded by the São Paulo Research Foundation -- FAPESP, and during a research internship abroad that was also supported by FAPESP .

"The material we synthesized can act as a photocatalyst to split water into hydrogen and oxygen, so that electricity can be generated from hydrogen, for example, as well as having several other potential applications," said Douglas Soares Galvão, one of the authors of the study and co-principal investigator at CCES.

The new material was exfoliated from hematite, one of the most common minerals on earth and the main source of iron, which is the cheapest metal, used in many products and above all to make steel.

----Hematene photocatalysis is more efficient because photons generate both negative and positive charges within a few atoms of the surface, the researchers said. By pairing the new material with titanium dioxide nanotube arrays, which provide an easy pathway for electrons to leave the hematene, the scientists found they could allow more visible light to be absorbed.

"Hematene may be an efficient photocatalyst, especially for splitting water into hydrogen and oxygen, and could also serve as an ultrathin magnetic material for spintronic-based devices," said the FAPESP RIDC researcher. Spintronics (or magnetoelectronics) is a new technology used to store, display and process information based on changes brought about by an electron's spin, which is directly coupled to its magnetic moment.

The group have investigated other non-van der Waals materials for their potential to give rise to other 2D materials with exotic properties. "There are a number of other iron oxides and derivatives thereof that are candidates for originating new 2D materials," Galvão said.

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