Noble-Metal-Free Colloidal-Copper Based Low Overpotential Water Oxidation Electrocatalyst

Water oxidation catalysis is gaining more attention in recent times owing to its potential for solar and chemical energy conversion and for green fuel generation. The overwhelming hurdle in this quest is to develop a noble-metal-free, efficient, low overpotential water oxidation electrocatalyst exhibiting tremendous stability and to be obtained from earth-abundant materials. We show here unique copper-based water oxidation electrocatalyst derived from thin film Cu-colloidal nanoparticles and is highly efficient, robust for water oxidation. The catalyst advantageously exhibits nanobeads and nanorods type mixed morphological features with narrow size distribution. The onset for oxygen evolution reaction occurs at a small potential of 1.45 V_RHE (η=220 mV) which is the lowest observed relative to other copper-based materials. The catalyst also maintains remarkable stability during long-term water electrolysis experiments. Moreover, the catalyst shown to exhibit a high electroactive area with a Tafel slope of 52 mV dec^1−, high TOF of 0.81 s¹⁻ and mass activity of 87 mA mg⁻¹. Copper is an interesting material because it can also serve as CO₂ reduction catalysts at the cathode side. The straightforwardly prepared, handy, and inexpensive Cu-based electrocatalytic system is a flexible catalyst for electrooxidation of water and for chemical energy conversion and is an attractive alternative to Pt, Ir, and Ru based electrocatalysts obtained from expensive resources and tedious methods.