Electro-Catalytic Activity of RuO<SUB>2</SUB>–IrO<SUB>2</SUB>–Ta<SUB>2</SUB>O<SUB>5</SUB> Mixed Metal Oxide Prepared by Spray Thermal Decomposition for Alkaline Water Electrolysis

Abstract

Oxygen evolution reaction for alkaline water electrolysis was studied using various mixed metal oxide catalysts. Mixed metal oxide electrodes consisting of RuO2, IrO2, and Ta2O5 with various ratios on a titanium substrate were prepared by spray thermal decomposition. The crystallinity of the synthesized catalyst was investigated via X-ray diffraction, and the oxidation state of each component was determined using X-ray photoelectron spectroscopy (XPS). Surface morphology was investigated by scanning electron microscopy, and the roughness factor was determined by cyclic voltammetry (CV) in 1 M H2SO4. Electo-catalytic activity for oxygen evolution reaction was measured by cyclic voltammetry (CV) in 1 M KOH at room temperature, and it was found to be strongly dependent.on composition of catalyst. Among all electrodes tested, catalyst with a composition of Ru:Ir:Ta = 1:2:2.5 exhibited the highest current density of 100 mA cm(-2) at 1.67 V, corresponding to an overpotential of 0.44 V.

Predicting aqueous stability of solid with computed Pourbaix diagram using SCAN functional

“…We note that when adding the aqueous ion TaO 2þ 2 in the Pourbaix diagram generation procedure (Supplementary Fig. 4), Ta 2 O 5 dissolves to TaO 2þ 2 in acid, contradicting experimental observations 25,26 . This is because Ta 2 O 5 is corroded in concentrated hydrofluoric or alkaline media 27 .…”

“…Tantalum pentoxide, Ta 2 O 5 , is barely reactive in aqueous solution and often serves as a catalyst or catalyst stabilizer for oxygen evolution in both acid and base because of its high aqueous stability 25,26 . We note that when adding the aqueous ion 2 in acid, contradicting experimental observations 25,26 . This is because Ta 2 O 5 is corroded in concentrated hydrofluoric or alkaline media 27 .…”

“…2f. Tantalum pentoxide, Ta 2 O 5 , is barely reactive in aqueous solution and often serves as a catalyst or catalyst stabilizer for oxygen evolution in both acid and base because of its high aqueous stability 25,26 . We note that when adding the aqueous ion TaO 2þ 2 in the Pourbaix diagram generation procedure (Supplementary Fig.…”

Electrocatalysts Derived from Metal–Organic Frameworks for Oxygen Reduction and Evolution Reactions in Aqueous Media

“…However, this catalyst severely suffers from crossover effect when being used in alcohol‐based fuel cells . RuO 2 and IrO 2 are outstanding OER catalysts offering low onset potentials (≈1.4 V), but their poor stabilities in alkaline solutions make them unsuitable for rechargeable metal–air batteries . Besides, the high cost, low reserve, and uneven distribution on earth are all bringing extra concerns on the large scale applications of these precious metal catalysts .…”

Predicting Aqueous Stability of Solid with Computed Pourbaix Diagram using SCAN Functional

“…Tantalum pentoxide, Ta 2 O 5 , is barely reactive in aqueous solution and often serves as a catalyst or catalyst stabilizer for oxygen evolution in both acid and base because of its high aqueous stability. 25,26 We note that when adding the the aqueous ion TaO 2+ 2 in the Pourbaix diagram generation procedure (Figure S4a-b These differences can be attributed to the uncertainties of the SCAN+U functional in calculating redox reactions energies of M 2+ → M 3+ → M 4+ . In particular, the relatively large differences between computation and experiment for Co and Ni is likely due to the influence of magnetic configurations.…”