Nanoimpact Electrochemistry to Quantify the Transformation and Electrocatalytic Activity of Ni(OH) 2 Nanoparticles: Toward the Size-Activity Relationship at High Throughput.

The fast establishment of structure-reactivity relationships is crucial to identifying the most appropriate nanoparticles (NPs) for a given application. This requires the development of methodologies allowing, simultaneously, the unraveling of the NPs geometry and the screening of their reactivity. Herein, nanoimpact electrochemistry (NIE) allows for quantifying the transformation and measuring the electrocatalytic activity for the oxygen evolution reaction (OER) of >100 Ni(OH) 2 NPs of a wide range of size (NP radii from 25 to 100 nm). This is achieved by scanning electrochemical microscopy in a generation/collection-like mode, with one electrode being used to electrogenerate by local precipitation colloidal Ni(OH) 2 NPs and the second one being used to collect them by NIE. It allows (i) quantifying the reductive and oxidative conversion of the Ni(OH) 2 NPs and (ii) separating the electrochemical conversion and the OER electrocatalysis, leading to the evaluation of a structure-activity relationship.