Seminar: Functional Characterization of Photoelectrodes by X-ray Photoemission Spectroscopies

The storage of intermittent solar energy in chemical bonds, i.e. Solar Fuels, is the most promising way to a future greener energy infrastructure. Chemical specificity in the investigation of the multiscale transient phenomena during semiconductor-driven photoelectrochemical (PEC) redox reactions is the key to a comprehensive understanding and modelling of the processes occurring in Solar Fuel generators. Interfacial energetics and dynamics crucially determine the performance of semiconductor photoelectrodes for (solar) chemical energy conversion. We use a suite of lab- and synchrotron-based X-ray photoemission spectroscopies to investigate interfacial energetics and dynamics in inorganic photoabsorbers. Examples comprise the elucidation of the role of polymorphic marcasite in pyrite (both FeS2) [1] in enhancing the photoresponse of pyrite based photoelectrodes as well as the evolution and tailoring of surface photovoltage in InP single crystal based model photocathodes for H2 evolution. [2] Employing XPS based surface photovoltage measurements, we determine the impact of photoreduced surface states in CuBi2O4 photocathodes on their photoresponse. Using the Eindhoven lab-based near-ambient pressure PES facility, the role of varying surface adsorbates could be studied, which is an important step forward towards bridging interface characterization in (ultra-high) vacuum-based and electrochemical conditions. In this lecture, I will highlight the X-ray photoemission methods used and showcase application examples on sulphide, phosphide and oxide photoabsorbers.

Thursday, February 27, 2020 - 11:15 to 12:15
Philipp Hofmann
Andrea Baldi