Electrocatalysis research has gained momentum recently owing to its crucial role in the conversion and storage of renewable energy. Numerous material science advancements have been demonstrated in fuel cells, water electrolysis, carbon dioxide, and nitrogen reduction technologies. Materials with high intrinsic catalytic activity and selectivity have been looked for in such research, aiming at improved performance and maximal product yields. However, approaching the commercialization stage, the research focus has shifted to the stability of electrocatalysts. Only materials that can demonstrate reliable operation over thousands to tens of thousands of hours are considered at this stage. Since typical testing time ranges are much shorter, a question arose – how can we quantify the degree of degradation and use it to predict stable operation over the years?

Numerous accelerated stress tests (AST) have been proposed to address this issue. Such tests imply that the underlying degradation governing mechanisms and their dependence on the device's operational conditions changes are well-known. Unfortunately, this is not the case for many technologies, sparking advancements in testing instrumentation development. Thus, the introduction of online inductively coupled plasma mass spectrometry (online ICP-MS) in the electrocatalysis research has assisted in resolving the mechanism of Pt dissolution in fuel cells and Ir dissolution in water electrolysis [1]. The application of identical location transmission electron microscopy (IL-TEM) has been crucial in understanding the morphological and compositional changes in the catalyst during the operation [2]. These techniques can also be combined with complementary surface science tools in in-situ and in-operando modes. When the catalyst layer rather than catalyst properties are to be studied, e.g., mass transport effects, gas diffusion electrode (GDE) half-cell setups are more suitable [3].

Despite the demonstrated benefits of such tools in electrocatalysis, their penetration in photoelectrocatalysis (PEC) research is still limited. This talk aims to change this status quo and motivate PEC researchers to adopt existing electrocatalysis techniques. To this end, a short overview will be given of how online ICP-MS, IL-TEM, GDE, and related methods have been used in fuel cell and water electrolysis research. A summary of our recent studies on the dissolution of representative photoabsorbers, such as Fe₂O₃, WO₃, BiVO₄, etc, and co-catalysts will follow this [4, 5]. The talk will be summarized by comparing and contrasting the state of the art in electrocatalysis and PEC research and discussing further tentative directions for the latter.