Effectual Water Oxidation Reinforced by Three-Dimensional (3D) MnO: A Highly Sustainable Electrocatalyst

Abstract

Fabricating highly effective, durable, eco-friendly, and low-cost electrocatalysts are challenging in renewable energy applications. Manganese(II) oxide (MnO), an oxygen evolution reaction (OER) catalyst, is an appealing contender in electrocatalytic water oxidation. Herein, we report the fabrication of single-phase MnO films over nickel foam (NF) as 3D electrode materials via a facile aerosol-assisted chemical vapor deposition (AACVD). HR-TEM confirms the nanoscale composition and polycrystalline structure, while the cauliflower-like morphology was observed under FE-SEM supported by EDX for conforming elemental composition. XRD and XPS analysis proved their chemical structure and oxidation states. The electrochemical investigations of MnO films prepared at 60 min revealed excellent OER performance in 1.0 M KOH. The benchmark decade current density was achieved just at an overpotential of 150 mV, whereas at an overpotential of 430 mV, Mn@NF-60 showed a maximum current density of 1158 mA cm–2 which is 4–6-folds better than its counterparts. The large electrochemical surface area (154 cm2), lower Tafel slope (80.93 mV/dec), and charge transfer resistance (18 Ω), excellent durability throughout extended chronopotentiometry analysis, and fast electron transfer reaction kinetics for OER comprehend Mn@NF-60 as an effectual electrocatalyst. These attributes of a single-phase MnO@NF-60 are credited to ample electroactive sites that enhance electron transfer processes. This study offered highly active single-phase metal oxide thin films by AACVD as 3D electrode materials for plentiful electrocatalytic applications.