Journal
CHEMISTRY OF MATERIALS
Volume 31, Issue 2, Pages 419-428Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acs.chemmater.8b03776
Keywords
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Funding
- Thousand Youth Talents Program
- National Natural Science Foundation of China [5171060]
- Australian Research Council [FT160100207]
- Australian Research Council [FT160100207] Funding Source: Australian Research Council
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Transition metal oxides are being actively pursued as low-cost electrocatalysts for the oxygen evolution reaction (OER) in many electrochemical energy devices. A fundamental understanding of the oxide electronic structures, along with the ability to rationally tune them, is a key step toward designing of highly active catalysts. Here, we report the tuning of the electronic structure of NiO via Li doping (LixNi1-xO) to enhance the OER activities. We identified that Li0.5Ni0.5O (LiNiO2) has the highest OER activity, comparable to or exceeding that of the benchmark perovskite Ba0.5Sr0.5Co0.8Fe0.2O3-delta and LaNiO3. More importantly, a synergistic combination of synchrotron-based photoemission spectroscopy, X-ray absorption spectroscopy, and density functional theory was used to unravel the electronic structure of LixNi1-xO with unprecedented accuracy, thus providing deep insight into the origin of the enhanced catalytic activity. The results unambiguously reveal the creation of a new hole state at 1.1 eV above the Fermi level and an enhanced degree of O 2p-Ni 3d hybridization induced by Li doping optimize the adsorption energetics of OH intermediates and thereby facilitate the fast kinetics for the OER. The LixNi1-xO would serve as a new platform to study the relationship of composition-electronic structure-activity for OER electrocatalysts, beyond the extensively studied Co-based perovskites.
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