Photoelectrochemical H2 production from water is a field of high present interest. This project is to design nanophotonics for efficient solar-to-H2 energy conversion. A method will be developed for fabricating nanophotonic structure (such as inverse opal photonic crystals, nanoarray photonic structure) of narrow band gap ternary metal oxide as photoanodes, for example, BiVO4 (2.4 eV), InVO4 (2.0 eV), BiFeO3 (2.2 eV), etc. Highly efficient solar-to-H2 energy conversion is expected to be achieved due to the superiorities of the structure and unique optical properties of nanophotonic structures, including stronger interaction between light and the photoelectrode induced by the stop-band edge effect, greatly improved light harvesting due to the multiple scattering effect, efficient photogenerated charge carriers separation due to the distance for photogenerated holes to reach the interface of semiconductor and the electrolyte can be significantly reduced. The proposed project will try to address how nanophotonic structures with their unique physical properties can enable efficient harvesting of light.