After a brief introduction on the principle of photoelectrochmical water splitting, we will present our recent results on water splitting photoelectrodes. Firstly, we show high performance Si-based water splitting photocathodes using transition metal chalcogenides (TMCs) such as MoS2, WS2, and MoP. It is emphasized that benign band bending and defect engineering of TMCs are crucial to enhance charge transfer processes between the light absorber and the catalytic layer and between the solid catalyst and the liquid electrolyte, respectively. Secondly, we show water oxidation performance of MnO/BiVO4/WO3/FTO photoanodes. It is revealed that charge transfer between MnO nanoparticles and the underlying BiVO4 layer is strongly depending on the ligands of MnO nanoparticles, by which the position of the band edges changes considerably. At last, we present our study on the role of plasmonic Au nanoparticles on water splitting activities of various metal oxide photonanodes. Our results indicate that shape control of Au nanoparticles is important and the catalytic hole transfer should be accompanied for direct electron injection from the nanoparticles to the metal oxide. It is shown that plasmonic resonance energy transfer can be dominant over direct energy transfer in Au nanoparticles/BiVO4 system.