Moving from materials to devices is unthinkable without a preceding thorough assurance of the durability of all of their constituent components. Considering the crucial green energy technologies, photovoltaic cells for renewable electricity generation and water electrolyzers for hydrogen production using renewables already demonstrate the required operational stability over years, if not decades. Unfortunately, the same cannot be said for the cells used for the photoelectrochemical water splitting. As for now, with numerous efforts toward optimizing the activity, the more significant challenge of tailoring the durability of photoelectrodes to meet industrially relevant levels remains. Considerable research efforts are necessary in order to improve our understanding of the degradation processes and develop mitigation strategies. Dissolution (as part of corrosion) is one of the degradation processes. This talk will present our most recent results on the dissolution of representative photoelectrodes (photoabsorbers with or without co-catalysts) during water splitting.

Over the last years, the dissolution stability of different electrocatalysts has been investigated in our group using an inductively coupled plasma mass spectrometer (ICP-MS) directly connected to an electrochemical cell [1]. In this configuration, time- and potential-resolved dissolution analysis is possible. Recently, such a cell was equipped with a solar simulator, Air Mass 1.5 G filter, and monochromator, allowing standardized photoelectrochemical measurements [2]. The dissolution stability of representative WO₃, BiVO₄, and Fe₂O₃ photoabsorbers was investigated in different electrolytes with or without a co-catalyst overlayer [3-5]. With the help of electrolyte and interface engineering, stabilization of the photoabsorbers was demonstrated. The gained insights can then be utilized to advance synthesis and operation approaches of novel materials with improved photostability.

Besides dedicated fundamental studies on well-defined electrodes, flow cell setups are well-suited for operation in a high-throughput manner [6]. This potential was realized in a proof-of-concept study on Fe–Ti–W–O thin film materials libraries using  fully automated activity-stability measurements [7]. Such a platform would enable material discovery, which is tailored to search not only for the most active but also for the most stable material.