Graphene oxide wrapped Mix-valent cobalt phosphate hollow nanotubes as oxygen evolution catalyst with low overpotential

Abstract

Development of an efficient, stable and inexpensive catalyst for oxygen evolution reaction (OER) is critical to electrochemical water splitting. In this regard, a precious-metal free electrocatalyst has been synthesized employing a hydrothermal route. The prepared graphene oxide wrapped cobalt phosphate nanotubes deposited on Ni foam electrode shows a low overpotential of 234 mV at a current density of 10 mA/cm² for OER in 1(M) KOH, lower than a benchmarking electrocatalyst IrO₂ at the same current density. The performance figures clearly defy the volcano limitations. The mixed-valency induced delocalization of charge satisfies Sabatier Principle for ideal catalysts and graphene oxide ensures improved charge transfer. Moreover, the designed electrocatalyst performs efficiently even on prolonged use under mass transfer limitation conditions.