Fabrication of Carbon-Platinum Interdigitated Array Electrodes and Their Application for Investigating Homogeneous Hydrogen Evolution Catalysis

Abstract

Interdigitated array electrodes (IDAEs) with one carbon electrode and the other platinum electrode were constructed by electrodepositing platinum on one set of the carbon electrodes. Platinum deposition was confirmed by scanning electron microscope (SEM) and cyclic voltammetry. The width of the carbon and platinum digits is less than 2 μm and the gap between two adjacent digits is around 3 μm. The carbon-platinum IDAEs benefit from the characteristics of both carbon and platinum in that carbon can provide a wide nonreactive potential window while platinum is a good catalyst for hydrogen reactions making it useful to characterize the catalytic hydrogen production cycle of the molecular electrocatalyst [Ni(PPh2NPh2)2(CH3CN)](BF4)2 (where PPh2NPh2 is 1,3,5,7-tetraphenyl-1,5-diaza-3,7-diphosphacyclooctane). With properly set potentials, the molecular electrocatalyst was reduced at the carbon digits to initiate a homogeneous H2 production reaction while the platinum digits detect the H2 by oxidation, providing direct evidence of its production rate from the catalytic cycles.