As the world transitions to a carbon neutral future, it is generally accepted that hydrogen plays an essential part as a fuel source. The use of solar energy as means of water splitting is among the most attractive prospects for generating green hydrogen. However up until now, large market deployment of photocatalytic and photoelectrochemical systems has not materialised owing to relatively low energy conversion efficiencies. The use of ferroelectric polarisation as a means of enhancing charge separation and thus improving energy conversion efficiency of these systems has been well reported. BiFeO₃-BaTiO₃ solid solutions have attracted widespread interest in recent years as a lead-free alternative to lead zirconate titanate (PZT), with both displaying enhanced ferroelectric polarisation within morphotropic phase boundary regions. With few ferroelectric materials attracting as much interest as BiFeO₃ for photocatalytic systems it is surprising BiFeO₃-BaTiO₃ has remained almost completely unexplored.
This work presents for the first time photoelectrochemical performance of BiFeO₃-BaTiO₃ solid solution thin films and powders as a photocatalyst for hydrogen generation under visible light irradiation. The charge transfer behaviour is explored by considering photoelectrochemical data as well as electrochemical impedance spectroscopy. Ferroelectric properties and photo-performance of this material system are thoroughly examined to elucidate the link between ferroelectric polarisation and photocatalytic performance.