In situ calorimetry at metal-electro de liquid electrolyte interfaces as monitored by probe beam deflection techniques

A probe beam deflection method that allows for the heat generated or absorbed during an interfacial process to be determined in situ is herein described. These optical measurements are performed using a collimated laser beam propagating parallel to the interface through the back of a flat, optically transparent ZnSe crystal that supports a very thin film of a metal electrode in contact with the electrolyte solution. Analysis of experimental data collected for a Au electrode in sulfuric acid aqueous solutions using numerical simulations were found to be consistent with the release of ∼375 kJ/mol upon formation of a monolayer of Au oxide. This value is very similar to the value observed using the same methodology for the reduction of the Au oxide layer under otherwise the same experimental conditions.