Synergistic 3D architecture of Fe-Co-Ni@CF/C-TiO2@NFF for high-performance electrochemical seawater splitting for hydrogen generation

Abstract

Background

Electrochemical water splitting, employing both the anodic oxygen evolution reaction (OER) and the cathodic hydrogen evolution reaction (HER), emerges as highly promising method for hydrogen production.

Methods

Herein the spray pyrolysis technique was utilized for the synthesis of novel electrodes of ternary mixed oxide of Fe, Co, and Ni and carbon doped titanium oxide (C-TiO₂) on a three-dimensional (3D) open-pore structure of Cu (CF) and Ni-Fe (NFF) foams, respectively. The electrocatalytic performances of these electrodes were then evaluated in three different electrolyte solutions: 1.0 M KOH, natural seawater, and buffered natural seawater.

Significant findings

The addition of buffer media (borate buffer) successfully overcame the challenges associated with seawater splitting. The required potential to reach a current density of 80 mA cm⁻² decreased drastically from 1.16 V vs RHE in seawater to just 968 mV in buffered seawater. Remarkably at a constant potential of 1.3 V vs RHE, the current density increased significantly from 93.3 mA cm⁻² for seawater to 200.8 mA cm⁻² for buffered seawater. Low Tafel slopes of 76 mV dec⁻¹ and 90 mV dec⁻¹ were observed for Fe-Co-Ni@CF and C-TiO₂@NFF electrodes, respectively.