An efficient palladium oxide nanoparticles@Co3O4 nanocomposite with low chemisorbed species for enhanced oxygen evolution reaction

Improved Activity of PdO Supported over Co3O4 in the Electrocatalytic Oxygen Evolution Reaction in a Wide pH Range

“…Scheme shows the most accepted OER mechanism proposed in the literature for a metal oxide MO x electrocatalyst in acidic and alkaline conditions. ,, The mechanism is based on four one-electron-transfer steps that take place at the surface of MO x . The oxidation of two water molecules and the release of four electrons subsequently are concomitant with the formation of oxygenated intermediates of the MO x such as hydroxide, oxide, and oxyhydroperoxide.…”

“…A similar mechanism was proposed for Co 3 O 4 and PdO@ Co 3 O 4 ; PdONPs deposited on Co 3 O 4 showed Tafel slopes of 58 mV dec −1 against Tafel slopes of 98 mV dec −1 for the pure oxide at pH 14. 19 A Tafel slope of 62 mV dec −1 was obtained for Co 3 O 4 supported on borophene decorated with AgNPs at pH 13, which was lowered by the AgNPs. 2 Electrocatalytic stability was tested by chronopotentiometry at a density current of 10 mA cm −2 in the FTO electrode for 2 h in all pH values (Figure 4I).…”

“…18 PdONPs deposited through UV light illumination over Co 3 O 4 samples presented low overpotential of 250 mV at 20 mA cm −2 and stability for 40 h at pH 14, which was attributed to the improved electrical conductivity. 19 Considering that Co 3 O 4 presented stability limited to an alkaline solution, while PdO stability goes from alkaline to slightly acidic pH, the combination of both materials was envisioned to improve the electrical conductivity, OER activity, and stability in a wide range of electrolytes and pH values. This approach also seeks to exploit the synergy between Co and Pd and to broaden the application of Earth-abundant transitionmetal compounds in the electrocatalytic OER.…”

“…The synergy between the elements often leads to improved OER electrocatalytic performance. Doping CoO x with a structural promoter such as Fe, Zn, Pb, Li, Pd, , Li, Ce, and Mn has enhanced the activity at alkaline pH. Doping with low amounts of noble metals has also been explored; for instance, Co 3 O 4 supported on borophene decorated with AgNPs showed enhanced OER performance attributed to the electrically conductive nature of AgNPs that facilitates the electron transfer from Co III atoms to form catalytically active Co IV sites .…”

“…The synergy of Pd and Co enhanced the interaction between the active oxygen species and the catalyst surface, creating oxygen vacancies in Co 3 O 4 . PdONPs deposited through UV light illumination over Co 3 O 4 samples presented low overpotential of 250 mV at 20 mA cm –2 and stability for 40 h at pH 14, which was attributed to the improved electrical conductivity …”