Co-based nanowire films as complementary hydrogen- and oxygen-evolving electrocatalysts in neutral electrolyte

Abstract

Designing and developing non-noble-metal electrocatalysts for efficient full water splitting at neutral pH is highly desired but still remains a huge challenge. In this communication, we report the development of homologous Co-based nanowire films, Co₂N nanowire film on a Ti mesh (Co₂N/TM) and Co-phosphate nanowire film on a Ti mesh (Co–Pi/TM), as complementary catalysts for stable electrochemical hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in neutral electrolyte. Co₂N/TM shows remarkable HER activity with the need of an overpotential of 290 mV to drive 10 mA cm⁻² in 1.0 M phosphate-buffered saline (PBS), and Co–Pi/TM is superior in OER activity affording 10 mA cm⁻² at overpotentials of only 430 and 300 mV in 0.1 and 1.0 M PBS, respectively. The two-electrode water electrolyzer using Co₂N/TM as a cathode and Co–Pi/TM as an anode affords a water-splitting current density of 10 mA cm⁻² at a cell voltage of 1.78 V with 100% Faradaic efficiency in 1.0 M PBS, promising the practical uses of such homologous Co-based catalyst materials in technological devices.