A yolk-shell structure construction for metal-organic frameworks toward an enhanced electrochemical water splitting catalysis

Novel mixed heterovalent (Mo/Co)Ox-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)Ox-Cu@NF display the formation of 3D hierarchical structure with a particle size range of 3-5 µm. The developed (Mo/Co)Ox-Cu@NF ternary electrocatalyst exhibits the maximum activity with 188 mV and 410 mV overpotentials at 50 mA cm-2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Electrochemical impedance spectroscopy (EIS) results for the (Mo/Co)Ox-Cu@NF sample demonstrate the minimum charge transfer resistance (Rct) 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-2 for overall water splitting (OWS). The electrocatalyst shows satisfactory durability during the OWS for 24 h at 10 mA cm-2 with an increase of only 33 mV in the cell potential.

Ultra-small RuO2/NHC nanocrystal electrocatalysts with efficient water oxidation activities in acidic media

RuO2/NHC3 with ultra-small and abundant electrochemically active sites requires a low overpotential of 186 mV at 10 mA cm−2 for acidic OER and maintains wonderful long-term stability within 27 h in 0.5 M H2SO4.