A Comprehensive Study of an earth-abundant bifunctional 3D electrode for efficient water electrolysis in alkaline medium

We produced an efficient electrocatalyst for both water splitting half reactions in the same medium, where the catalyst compromise Co3O4 nanospheres attached on the surface of nitrogen-doped carbon nanotubes, which in turn are directly grown on conductive carbon paper. The firm and well-established interfaces along the electrode play a crucial role on enhanced stability and electrochemical activity observed for both oxygen evolution reaction and hydrogen reduction reaction. The manuscript has been published in the ACS Applied Materials and Interfaces.

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Tiva Sharifi, Eduardo Gracia-Espino, Xueen Jia, Robin Sandström, and Thomas Wågberg

ACS Appl. Mater. Interfaces, 2015
DOI: 10.1021/acsami.5b10118

Abstract

We report efficient electrolysis of both water splitting half reactions in the same medium, by a bifunctional 3D electrode comprising Co3O4 nanospheres nucleated on the surface of nitrogen-doped carbon nanotubes (NCNTs) which in turn are grown on conductive carbon paper (CP). The resulting electrode exhibits high stability and large electrochemical activity for both oxygen and hydrogen evolution reactions (OER and HER). We obtain a current density of 10 mA/cm2 in 0.1 M KOH solution at overpotentials of only 0.47 V and 0.38 V for OER and HER respectively. Additionally, the experimental observations are understood and supported by analyzing the Co3O4:NCNT and NCNT:CP interfaces by ab initio calculations. Both the experimental and the theoretical studies indicate that firm and well-established interfaces along the electrode play a crucial role on the stability and electrochemical activity for both OER and HER.