Structural and electrochemical characterization of iron nickel hydroxide electrocatalyst for highly efficient water splitting applications

• Main Author: Nicholas
• Other Authors: Lydia Helena Wong
• Format: Final Year Project
• Language: English
• Published: 2016
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/68754
• Institution: Nanyang Technological University

The growing demand of energy coupled with the limited supply of the major energy sources such as fossil fuels has motivated the scientific community to explore renewable energy sources. Among them, hydrogen energy has been a promising alternative energy source due to its renewability, environmental friendliness, and high energy density. One of the inexpensive and eco-friendly methods to produce hydrogen gas includes electrocatalytic water splitting. However, the oxygen evolution reaction in this process remains as a bottleneck of the overall process due to its slow kinetics. As a result, a highly efficient oxygen evolution electrocatalyst is required to reduce the typically high overpotential of the overall reaction. Significant amount of research effort has been conducted on the application of first row transition metal compound as oxygen evolution catalyst due to their abundance, typical long term stability, and ability to sustain water oxidation reaction under mild pH conditions. Here we demonstrate that a highly efficient oxygen evolution electrode can be developed by depositing iron-nickel hydroxide catalyst on porous nickel foam substrate via hydrothermal method. The grown FeNi hydroxide structure resembled a mixture of nanorods and nanoplates, which led to significantly higher electrocatalytic activity. This is as a result of higher surface area provided by the structure as compared to the pure nickel foam alone without any deposition. Significantly low overpotential of ~140 mV in 1 M NaOH electrolyte was required for water oxidation reaction to occur. In addition, current density of 10 mA cm-2, which translates to the current density expected for 10% solar-to-fuels conversion, was achieved with overpotential as low as 165 mV. This is among the highest electrochemical performance for oxygen evolution reaction ever reported in the literature. Improved reaction kinetics (i.e. Tafel slope as low as 71.96 mV dec-1 in 1 M NaOH) as well as relatively good stability even in high electrolyte concentration were also observed following the incorporation of FeNi hydroxide to the substrate. This highly efficient FeNi hydroxide on nickel foam electrode possesses huge potential for large-scale water splitting applications due to its low cost, abundance, and durability while exhibiting outstanding performance as a promising oxygen evolution electrode.