What type of semiconductor uses high-energy ultraviolet light to generate electrons for carbon dioxide transformation?

The correct choice is photocatalyst. Photocatalysts are materials that accelerate chemical reactions upon exposure to light, particularly ultraviolet (UV) light. When high-energy UV light is applied to a photocatalytic semiconductor, it generates electron-hole pairs. These electrons can then take part in chemical reactions, such as the transformation of carbon dioxide into more useful compounds, effectively harnessing the energy from light to drive reactions that would otherwise require more energy.

In the context of carbon dioxide transformation, photocatalysts are crucial because they can utilize sunlight to promote reactions that can help mitigate the impact of greenhouse gases, converting carbon dioxide into fuels or other chemicals. This process is part of a broader effort to develop sustainable energy solutions and reduce atmospheric CO2 levels.

Other options, while related to technological advancements, do not fulfill the specific requirement of generating electrons through UV light for carbon dioxide transformation. Photovoltaic cells, for example, are designed to convert light energy directly into electrical energy but do not specifically serve the purpose of catalyzing chemical transformations. Thermistors and superconductors have different applications entirely and are not involved in catalysis or light-driven chemical processes.