Necklace-like Multishelled Hollow Spinel Oxides with Oxygen Vacancies for Efficient Water Electrolysis

Abstract

The durability and reactivity of catalysts can be effectively and precisely controlled through the careful design and engineering of their surface structures and morphologies. Herein, we develop a novel "adsorption-calcination-reduction" strategy to synthesize spinel transitional metal oxides with a unique necklace-like multishelled hollow structure exploiting sacrificial templates of carbonaceous microspheres, including NiCoO (NCO), CoMnO, and NiMnO. Importantly, benefiting from the unique structures and reduction treatment to offer rich oxygen vacancies, the unique reduced NCO (R-NCO) as a bifunctional electrocatalyst exhibits the dual characteristics of good stability as well as high electrocatalytic activity for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). At 1.61 V cell voltage, a 10 mA cm water splitting current density is obtained from the dual-electrode, alkaline water electrolyzer. Calculations based on density functional theory (DFT) reveal a mechanism for the promotion of the catalytic reactions based on a decrease in the energy barrier for the formation of intermediates resulting from the introduction of oxygen vacancies through the reduction process. This method could prove to be an effective general strategy for the preparation of complex, hollow structures and functionalities.

Phosphorus Incorporation into Co9S8 Nanocages for Highly Efficient Oxygen Evolution Catalysis

“…Inspired by the above theoretical studies, we prepared P‐Co 9 S 8 nanocages by using Cu 2 O nanocubes as sacrificial templates (see the detailed synthesis process in Figure S1 in the Supporting Information). It is noted that the high specific surface area and porous shell from hollow structure endow the catalysts with rich active sites, local chemical microenvironment, and high charge transfer rate, which contributes to forming a favorable catalytic interface between catalysts and electrolytes, thus contributing to improving OER performance . First, Cu 2 O nanocubes as sacrificial templates are fabricated by a previously reported wet‐chemical route (Figure S2, Supporting Information) .…”

Nickel Foam‐Supported Amorphous FeCo(Mn)−O Nanoclusters with Abundant Oxygen Vacancies through Selective Dealloying for Efficient Electrocatalytic Oxygen Evolution

“…The plasma‐engraved Co 3 O 4 nanosheets with abundant O‐vacancies show an overpotential of 300 mV at 10 mA cm −2 , a remarkably decreased overpotential by 240 mV than its pristine counterpart . Due to the greatly lowered energy barrier of the formation of OER intermediates by O‐vacancies, the reduced NiCo 2 O 4 by NaBH 4 treatment with necklace‐like multi‐shelled hollow structure only needs less overpotential by 40 mV than that of the pristine spinel oxide …”

Nickel‐Based Transition Metal Nitride Electrocatalysts for the Oxygen Evolution Reaction

“…[1][2][3] Among the cleanest routes to produce energy is through the production of hydrogen, ideally through water splitting. [1][2][3] Among the cleanest routes to produce energy is through the production of hydrogen, ideally through water splitting.…”

“…d) Nyquist plots for bulk Ni 3 Na nd NiO nanosheets.e )Stability of Ni3 Nn anosheets. c) OER activity at 100 mA cm À2 per geometric area.…”