Efficient overall water splitting of Mo-doped Co3O4 electrocatalyst: An X-ray spectroscopic investigation

Pandian Mannu^1*, Ta Thi Thuy Nga^1,2, Yu-Cheng Huang³, Jeng-Lung Chen³, Asokan Kandasami⁴, Wu-Ching Chou², Chi-Liang Chen³, Chung-Li Dong¹

¹Research Center for X-ray Science & Department of Physics, Tamkang University, New Taipei City 25137, Taiwan
²Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
³National Synchrotron Radiation Research Center, Hsinchu, Taiwan
⁴Department of Physics & Centre for Interdisciplinary Research, University of Petroleum and Energy Studies (UPES), Dehradun, India

* Presenter:Pandian Mannu, email:pandianphy@gmail.com

The oxygen evolution reaction (OER) and Hydrogen evolution reaction (HER) are essential for electrochemical energy conversion technologies. Reasonably manipulating surface reconstruction of catalysts for water oxidation, inducing formation and dynamic accumulation of catalytically active centers still faces several challenges. Herein, the doping of Mo into Co3O4 by intercalation engineering to promote surface reconstruction achieves a progressive OER and HER activity. A simple hydrothermal approach was used to synthesize the Co3O4 and Mo-doped Co3O4 microsphere. The SEM and TEM images confirm that the microsphere structure becomes smaller in Mo-doped Co3O4. Overall Mo-doped Co3O4 catalysts exhibit a significant enhancement in the OER and HER activity and outperform the Co3O4 catalyst. X-ray absorption spectroscopy results reveal the contraction of the Co-O and Mo-O bond in Mo-doped Co3O4 due to the existence of a higher oxidation state of Co and Mo. Moreover, the optimal Mo-doped Co3O4 catalyst also shows an excellent Urea oxidation reaction (UOR). This study provides insights into the facile fabrication of novel catalysts for dual electrocatalytic water and urea oxidation reactions.

Keywords: Water splitting, X-ray absorption spectroscopy, Oxygen evolution reaction, Urea oxidation reaction