Iron-based photocatalytic and photoelectrocatalytic nano-structures: Facts, perspectives, and expectations

The increasing demand for clean renewable energy needed for sustainable industrial progress and population growth is the driving force for the scientific community to achieve a continuous development in the field of photocatalysis and photoelectrochemistry. Nanostructures and nanomaterials have contributed significantly to the field of renewable energy due to their new physicochemical properties. Iron-based nanostructures have considerable advantages like small band gaps, allowing to harvest photons in the visible region of the solar spectrum, abundance, and important physical properties like magnetism and ferroelectricity. But they also have many shortcomings and drawbacks related to stability in the different photocatalytic media, low surface area, conductivity, and fast charge carrier recombination. In this review, the focus is placed on important members of the iron-based photocatalyst family such as, hematite, iron oxy-hydroxide, iron-based perovskites, and spinel ferrites. Also, iron doped titanium dioxide as visible light photocatalysts is covered. Various strategies employed for enhancing the photocatalytic and photoelectrocatalytic performance are discussed. Doping, oxygen vacancies, induced defects and formation of solid solutions seem to be a working strategy to address some of the challenges in photocatalysis and photoelectrocatalysis. Finally, photocatalytic and photoelectrocatalytic applications employing iron-based semiconductors are presented.