Microfluidic Tuning of Individual Nanoparticles to Understand and Improve Electrocatalysis

Transition metal based nanoparticles (NPs) are envisioned as viable alternatives to the scarce precious metal based catalysts used today for renewable energy conversion.

Yet, probing their intrinsic activity to establish property-activity relations and so to smartly design superior catalysts, is impeded by two limitations of existing electrocatalytic techniques.

First, the integral assessment of ensembles of non-identical NPs prohibits the identification of intrinsic activity differences.

Second, the unknown effects of additives required analyzing the activity of often poorly conductive transition metal oxides, e.g. during the oxygen evolution reaction (OER), prohibit the access to quantitative data and comparable benchmarks. Very recently, we have proposed single NP electrochemistry to overcome both limitations.

We demonstrated that the electrocatalytic OER response of individual CoFe2O4 NPs can be assessed in the absence of additives.

However, we have not been able to extract property-activity relations, as NP characterization was limited to ex situ data.

The groundbreaking strategy of this work is to combine intrinsic activity and physical property measurements of individual NPs.

Physical characterization will comprise different online and ex situ methods to gain comprehensive property information.

Numerical simulations will allow us to extract quantitative kinetic data from the electrochemical studies, allowing us to provide quantitative benchmarks of intrinsic catalyst performance. Cycling of NPs in a microfluidic platform will enable degradation studies and systematic modification on the fly.

Moving towards application conditions, catalyst-support interactions will be studied by stepwise immobilization of catalysts on substrates.

As a result of revealing intrinsic property-activity relations in electrocatalysis and of elucidating catalyst-support interactions, we will gain the understanding urgently needed to disruptively change electrocatalyst devolopment.