Pd-Modified De-alloyed Au−Ni-Microelectrodes for In Situ and Operando Mapping of Hydrogen Evolution

Abstract

To date most studies focusing on light-driven water splitting for green energy conversion schemes depend on bulk analyses of the produced hydrogen using, e. g., head-space gas chromatography. In this contribution, we present the fabrication of Pd-modified microelectrodes for in situ electrochemical hydrogen measurements using de-alloyed Au−Ni microelectrodes. Stability studies and pH-dependent investigations revealed the stability of these microsensors over a period of seven days, and confirmed their applicability in a pH range of 3–10 with a limit of detection (LOD)<1 μmol/L. First in situ proof-of-principle electrochemical imaging of hydrogen generated at a microelectrode and operando studies of hydrogen evolution at earth-abundant cobalt hydrogen evolution catalysts using the developed Pd-microsensors in combination with scanning electrochemical microscopy (SECM) demonstrated the potential of these microsensors for operando studies in light-driven heterogeneous catalysis.