Hydrogen (H2) has proved itself as a viable future energy carrier and alternative for fossil fuel in terms of ensuring a clean and sustainable energy supply. However, H2must be made available at a lower cost so that everyone can benefit from it and prevent causing a worldwide ecological imbalance. The usage of photoelectrochemicalwater splitting (PEC) technology by using TiO2photocatalyst can produce H2 using renewable solar energy. The essential milestones, as well as the mechanism in PEC H2generation, are discussed in this article