Rational Design of Semiconductor for Photoelectrochemical Water Splitting

The search for semiconducting materials for commercially viable photoelectrochemical (PEC) water splitting has been extremely challenging. Meeting that challenge requires the engineering of a semiconductor with the following tightly coupled material property criteria: appropriate band gap (1.6 – 2.2 eV), efficient visible light absorption, high carrier mobility, correct band edge positions that straddle the water redox potentials, and durability in solution environment. In this talk, I will discuss some general strategies for the rational design of semiconductors to simultaneously meet the requirements for a high efficiency solar-driven PEC water splitting devices. Density functional theory (DFT) calculations reveal that with appropriate donor-acceptor pairs or acceptor-acceptor co-incorporation, anatase TiO₂ holds great potential for a viable PEC device. Other approaches to modify the band structure of TiO₂, such as the application of strain and band structure engineering of other materials such as CoX₂O₄ and BiVO₄, will also be discussed.