Bifunctional non-noble metal oxide nanoparticle electrocatalysts through lithium-induced conversion for overall water splitting

Haotian Wang; Hyun-Wook Lee; Yong Deng; Zhiyi Lu; Po-Chun Hsu; Yayuan Liu; Dingchang Lin; Yi Cui

doi:10.1038/ncomms8261

Bifunctional non-noble metal oxide nanoparticle electrocatalysts through lithium-induced conversion for overall water splitting

Nat Commun. 2015 Jun 23:6:7261. doi: 10.1038/ncomms8261.

Authors

Haotian Wang¹, Hyun-Wook Lee², Yong Deng², Zhiyi Lu², Po-Chun Hsu², Yayuan Liu², Dingchang Lin², Yi Cui³

Affiliations

¹ Department of Applied Physics, Stanford University, Stanford, California 94305, USA.
² Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA.
³ 1] Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA [2] Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road Menlo Park, California, 94025, USA.

Abstract

Developing earth-abundant, active and stable electrocatalysts which operate in the same electrolyte for water splitting, including oxygen evolution reaction and hydrogen evolution reaction, is important for many renewable energy conversion processes. Here we demonstrate the improvement of catalytic activity when transition metal oxide (iron, cobalt, nickel oxides and their mixed oxides) nanoparticles (∼20 nm) are electrochemically transformed into ultra-small diameter (2-5 nm) nanoparticles through lithium-induced conversion reactions. Different from most traditional chemical syntheses, this method maintains excellent electrical interconnection among nanoparticles and results in large surface areas and many catalytically active sites. We demonstrate that lithium-induced ultra-small NiFeOx nanoparticles are active bifunctional catalysts exhibiting high activity and stability for overall water splitting in base. We achieve 10 mA cm(-2) water-splitting current at only 1.51 V for over 200 h without degradation in a two-electrode configuration and 1 M KOH, better than the combination of iridium and platinum as benchmark catalysts.