Recently, great attention has been focused on hydrogen as a potential energy vector and on the use of water-splitting technology as a clean and renewable means to generate hydrogen using solar energy. Numerous attempts have been made to develop photo-catalysts that work not only under UV light but also under visible-light illumination to efficiently utilize solar energy. In this talk, I will discuss about photoelectrochemical water splitting and demonstrate the fabrication of visible-light-responsive heterostructured Cr-doped SrTiO3/TiO2 nanotube arrays by a simple hydrothermal method, which facilitate efficient charge separation and thus improve the photoelectrochemical performance.