Single and multi-barrel nanopipettes and nanopipette-based scanning electrochemical probe microscopy techniques like scanning electrochemical cell microscopy (SECCM) have gained significant attention as tools for localized, maskless, three-dimensional surface modifications [1,2]. The nanometer-sized orifices of nanopipettes allow delivering molecules to solution inducing concentration-confined electrodepositions. Also, electroless nanoscale depositions like the fountain pen technique [3] can be achieved by this technique.

In this study, we present the deposition of various cobaloxime-based earth-abundant Co catalysts for light-driven hydrogen evolution reaction (HER) [4]. Arrays of different cobalt(III) complexes were deposited via SECCM and investigated in respect with their HER activity using scanning electrochemical microscopy (SECM) in combination of Pd-microsensors [5] for in situ hydrogen (H₂) measurements under illumination. In addition, AFM studies revealed possible degradation of the commercially available neutral benchmark complex [Co(dmgH)₂(py)Cl] in these studies. First results will also be presented in respect with the deposition of nanowires via co-deposition of HER catalyst and Ruthenium photosensitizer. First spatially resolved photocatalytic studies at such nanowires, which are characterized by high surface area, will be presented. Also, the influence of the substrate will also be discussed.

References:

1. Oswald, K. Palanisamy, C. Kranz, Curr. Op. Electrochem. 34, 100965 (2022).
2. Hengsteler et al., Nano Lett. 21, 9093 (2021).
3. -H. Kim, N. Moldovan, H.D. Espinosa, Small 1, 632, (2005).
4. Oswald et al., Chem. Eur. J. 27, 16896 (2021) and corrigendum (2022); doi:10.1002/chem.2022008809.
5. Kund et al., ChemElectroChem 9, e202200071 (2022)

Funding by the German Science Foundation (DFG) – project number 364549901 – TRR 234 (projects B7, C4).