Novel mixed heterovalent (Mo/Co)O-zerovalent Cu system as bi-functional electrocatalyst for overall water splitting.

A novel hybrid ternary metallic electrocatalyst of amorphous Mo/Co oxides and crystallized Cu metal was deposited over Ni foam using a one-pot, simple, and scalable solvothermal technique. The chemical structure of the prepared ternary electrocatalyst was systematically characterized and confirmed via XRD, FTIR, EDS, and XPS analysis techniques. FESEM images of (Mo/Co)O-Cu@NF display the formation of 3D hierarchical structure with a particle size range of 3-5 µm. The developed (Mo/Co)O-Cu@NF ternary electrocatalyst exhibits the maximum activity with 188 mV and 410 mV overpotentials at 50 mA cm for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Electrochemical impedance spectroscopy (EIS) results for the (Mo/Co)O-Cu@NF sample demonstrate the minimum charge transfer resistance (R) and maximum constant phase element (CPE) values. A two-electrode cell based on the ternary electrocatalyst just needs a voltage of about 1.86 V at 50 mA cm for overall water splitting (OWS). The electrocatalyst shows satisfactory durability during the OWS for 24 h at 10 mA cm with an increase of only 33 mV in the cell potential.