Hybrid CoP2–Pt–FTO nanoarchitecture for bifunctional electrocatalysts in H2 generation by water splitting

Abstract

The development of superior electrocatalysts is an essential step in the advancement of hydrogen energy generation by the electrocatalytic water splitting and the properties being required are bifunctionality, low overpotential, elemental abundance of electrode materials, stability, and low cost. In this work, a hybrid nanoarchitecture of CoP2–Pt–FTO is demonstrated for the bifunctional operations in the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) of overall water splitting in a single alkaline solution. The bifunctional hybrid nanoarchitecture comes in a simple configuration, incorporating the CoP2 nanoparticles of highly efficient OER component on a thin Pt layer of excellent HER element. The hybrid electrode demonstrates the low overpotentials of 265 and 19.4 mV at a current density of 10 mA/cm2 for the OER and HER, respectively, in a single alkaline solution of 1.0 M KOH. A low cell voltage of 1.52 V is demonstrated with an excellent stability at 10 mA/cm2 for the bifunctional operation of the hybrid electrode. In the hybrid nanoarchitecture, the Pt atoms can play a role of high electrochemical active sites for the Pt−Hads formation, thus improving the HER. At the same time, the thin Pt layer can also provide a good conducting template for the fabrication of CoP2 nanoparticles by the electrochemical deposition. The positively charged Co+ atoms can actively absorb the hydroxyl receptors (OH−), thus improving OER. Simultaneously, the negatively charged P− atoms can promote the adsorption of H+ protons, thus contributing to the HER. Various hybrid electrode catalysts are successfully fabricated by the control of deposition temperature of CoP2 and thickness of Pt layer, that is, CoPx/Pty, where x is deposition temperature and y Pt thickness and demonstrate the excellent simultaneous operations of OER and HER in a single alkaline solution.