Photocatalysis offers a pathway for green energy and chemical industry alternatives such as sunlight-driven water splitting and CO 2 reduction. In such processes, solar-to-chemical energy conversion provides the driving force to generate renewable fuels and chemicals as a promising solution to the energy and environmental crisis. In short, vastly available sunlight in a photocatalytic system is absorbed, followed by photo-generation of separated charge carriers in the material valence (VB) and conduction (CB) bands. These charge carriers can participate in the desired surface reactions. Whether the promise of a photocatalysis-based sustainable future can reach industrial plants strongly depends on finding a material that can optimally fulfill requirements for each step of a photocatalytic process. An ideal photocatalyst should have valence and conduction band edges straddling the potentials of the targeted redox reactions, should absorb visible light, display high charge-carrier mobility, and have low detrimental electron-hole recombination.