Metal and metalloid oxides have a ubiquitous presence in modern life. The most popular examples, silicon dioxide (SiO2), iron oxide (Fe3O4), aluminium oxide (Al2O3) and titanium dioxide (TiO2), are earth-abundant and have a variety of applications, which include the catalyst for the fixation of nitrogen (Fe3O4) and the fabrication of microelectronic components (SiO2). The ability to control and tune the properties of earth-abundant oxides through mild and operationally straightforward methods is crucial to the expansion of their applications. In recent years, TiO2 has been extensively studied to exploit its semi-conducting and light absorption properties. A particular area of interest is to maximize the percentage of sunlight that TiO2 can absorb as it is limited to the UV range, which makes up only 7 % of sunlight. It has been demonstrated that dye sensitization, elemental doping with light elements such as carbon and nitrogen, and defect engineering can deliver subtle changes to the electronic and optical properties of the oxide. Here, we introduce a new strategy we refer to as “molecular doping”, whereby stable boron-rich clusters are incorporated into the framework of a metal oxide. This dramatically changes the photophysical properties of TiO2, producing a hybrid material capable of absorbing light beyond the UV regime. Importantly, this unique absorption results in visible light-driven photocatalytic activity. This approach can also be used to access other hybrid metal oxides including Al2O3 and ZrO2. For the first time, our study shows how stable boron-rich clusters can be used as molecular precursors and can be efficiently interfaced with solid-state materials to enable new properties.

Molecular doping approach for metal oxide photosensitization

253rd National Meeting (2017)

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