Printed Co₃O₄ film as an electrocatalyst for hydrogen production by a monolithic photovoltaic-electrolysis system

In a monolithic photovoltaic-electrolysis system, photovoltaic and catalytic layers are generally constructed on both sides of a conducting substrate. For the realization of this architecture it is critical to fabricate the catalytic layer at sufficiently low temperature in order not to deteriorate the photovoltaic photoanode that is already installed on the reverse side of the catalytic layer. In this study we demonstrate successful fabrication of Co ₃O₄ electrocatalyst films at low temperature (∼50 ^°C) on a stainless steel substrate by a paste coating method using Nafion as a binder. The Co₃O₄ films were found to be catalytically efficient and stable in water splitting reaction in an alkaline aqueous solution. More importantly, the Co₃O₄ films casted at low temperature (∼50^°C) revealed the highest hydrogen production rate in the electrolytic cell compared to the films prepared at higher temperatures (e.g. 150 and 300^°C), which would be very beneficial in the construction of a monolithic photovoltaic-electrolysis system.