The Necessity for Multiscale In Situ Characterization of Tailored Electrocatalyst Nanoparticle Stability †

Abstract

Tailored nanoparticles have opened up several exciting avenues to boost the activity and selectivity of structure-sensitive electrocatalytic reactions, such as the electrochemical carbon dioxide (CO2) reduction (eCO2RR). Colloidal chemistry provides the perfect toolbox to synthesize electrocatalyst nanoparticles on demand with atomic precision, in order to control and steer the electrocatalytic reactions of interest to the desired products. Not only does colloidal chemistry offer a means to prepare nanoparticles with well-defined sizes and shapes, it also allows easy deposition on any desired substrate (e.g., porous substrates) due to the solution processability. But what you see after synthesis with ex situ characterization techniques is not always what you get during the electrocatalytic reaction. Like any other electrocatalyst material, colloidal nanoparticles are prone to restructuring, and hence, the reaction output is altered due to destabilization of the electrocatalyst. This destabilization of the electrocatalyst nanoparticles is currently one of the major bottlenecks for the widespread implementation of electrocatalysts in the chemical industry. This calls for the necessary development and application of in situ characterization techniques to probe the morphology and composition of the tailored electrocatalyst nanoparticles over multiple length scales, in order to rationally design the next generation of stable electrocatalyst nanoparticles. Through detailed spatiotemporal in situ characterization, we can take full advantage of the possibilities that colloidal chemistry offers for electrocatalyst preparation with superior activity, selectivity, and stability. In this perspective, the necessity for in situ characterization of electrocatalyst nanoparticle stability is highlighted. For this purpose, first the progress of colloidal nanoparticles for electrocatalytic conversion reactions is briefly discussed, after which the focus shifts toward in situ characterization of the (in)stability of the tailored nanoparticles during the reaction of interest, ideally under industrially relevant conditions. This perspective shows that in situ characterization of electrocatalyst deactivation requires a multiscale approach, and that without combined in situ characterization we will remain blind to several aspects that are known to influence electrocatalyst performance.