Enhanced hydrogen/oxygen evolution and stability of nanocrystalline (4–6 nm) copper particles

Abstract

The exploration of nanomaterials as catalysts for hydrogen and oxygen evolution is highly desirable for renewable and clean energy applications. We have obtained highly efficient and stable copper nanoparticles (4–6 nm) by thermal decomposition of aligned copper oxalate nanorods (obtained by a microemulsion method) in an argon atmosphere. Hydrogen and oxygen evolution reactions (HER and OER) were carried out on glassy carbon as well as platinum as working electrodes in KOH solution. In the case of HER the current densities were found to be 12 mA cm⁻² (glassy carbon electrode) and 46 mA cm⁻² (Pt electrode) which are significantly higher than reported values (maximum 1 mA cm⁻²). In the case of OER the current density was found to be 1.6 mA cm⁻² (which is slightly higher) for the glassy carbon electrode and 15 mA cm⁻² for Pt as the working electrode which is 4–30 times higher than earlier reports. The high efficiency can be related to the high surface area (34 m² g⁻¹) of these tiny well-crystalline copper nanoparticles obtained by the microemulsion mediated synthesis. The copper nanoparticles obtained by us show excellent stability as electrocatalysts and retain their activity even after 50 cycles.