Controlled Synthesis of 2D Nanostructured Bimetallic Oxide (NiMoO4) on Self-Supported Nickel Foam for Boosted Electrocatalytic Seawater Oxidation Performance

Abstract

The design and development of effective electrocatalysts containing nonprecious materials for oxygen evolution reaction (OER) in seawater splitting remains a significant challenge for large-scale industrial hydrogen production. Nonprecious bimetallic oxide-constructed catalysts are utmost promising candidates to obtain boosting electrochemical water oxidation performance. Herein, a transition bimetallic oxide nanostructure electrocatalyst as NiMoO₄ vertically standing nanosheet over the nickel foam substrate (NiMoO₄/NF) for electrochemical water oxidation process in alkaline fresh/simulated seawater conditions is presented. NiMoO₄ nanostructure on NF substrate is successfully obtained using a straightforward hydrothermal reaction route and thermal annealing processes. The surface morphology with elemental characteristics of the resultant NiMoO₄/NF sample exposes highly homogenous vertical standing nanosheets assembled on the NF surface. The electrochemical water oxidation performance of the as-prepared electrodes demonstrates the function of diverse hydrothermal reaction times (3, 6, and 9 h) in fresh and simulated seawater electrolyte conditions. In alkaline seawater electrolyte conditions, optimal hydrothermal reaction time-assisted NiMoO₄/NF-6 h electrocatalyst possesses significant OER electrocatalytic actives compared to the other samples. Similarly, NiMoO₄/NF-6 h catalyst exhibits a small overpotential of 429 mV to achieve a current density of 50 mA cm⁻² with a Tafel slope value of 122 mV dec⁻¹ for OER process. As a result, the resultant superior electrocatalytic performance of the optimal hydrothermal reaction time-aided electrocatalyst (NiMoO₄/NF-6 h) is ascribed to highly accessible catalytic active centers and enhanced charge transfer kinetics at the interface for electrochemical reactions. Thus, proposed nanostructure-constructed electrocatalysts could prove to be prospective OER candidates for electrochemical water oxidation.