Improving water-splitting oxygen evolution reaction activity of MoO 3 by incorporation of Li+ ions Yun-Hyuk Choi 1 , Kyeong-Ho Kim, 2 Daehyun Hong, 1 Myeong Gyu Kim, 1 Wooseon Choi, 3 Taewon Min, 4 Young-Min Kim, 3 1 Department of Advanced Materials and Chemical Engineering, Daegu Catholic University, Gyeongsan 38430, Gyeongbuk, Republic of Korea, 2 Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, Unites States of America, 3 Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea, 4 Department of Physics, Pusan National University, Pusan 46241, Republic of Korea E-mail: yunhyukchoi@cu.ac.kr Molybdenum trioxide (MoO 3 ) is one of the candidate electrocatalysts for water-splitting hydrogen generation based on its low cost, nontoxicity, and high chemical stability, where the electrochemical water electrolysis consists of the hydrogen and oxygen evolution reactions (HER and OER). In particular, several polymorphs of MoO 3 with different crystal and electronic structures provide many opportunities to find suitable electrocatalysts. So far, a promising electrocatalytic activity for the HER has been found for orthorhombic structure of α-MoO 3 , while it has showed a poor intrinsic activity for the OER. In this work, it is found that the intrinsic OER activity of orthorhombic α-MoO 3 is remarkably improved by incorporating guest ions of lithium-ion (Li + ). α-MoO 3 nanoparticles were firstly deposited on a carbon fiber paper substrate (α-MoO 3 /CFP) by chemical vapor transport and subsequent lithiation process was applied to prepare lithiated α-MoO 3 /CFP (Li-α-MoO 3 /CFP) electrode, showing the robust η 10 of 458 mV. The improved OER activity in the lithiated electrode is attributed to the incorporation of Li + into the MoO 3 phase, which increases the electron carrier density and the corresponding electrical conductivity, thereby improving the interfacial charge transfer kinetics as well as activating a large number of the electrochemically active surface area (ECSA) leading to the fast OER kinetics. This study not only shows a realistic boost in the electrocatalytic activity of inexpensive transition metal oxide catalysts by guest-ion incorporation, but also provides insights into the design of new electrocatalysts. PS: This work was published recently [1] . References 1. Improving Electrocatalytic Activity of MoO 3 for the Oxygen Evolution Reaction by Incorporation of Li Ions,Kyeong- HoKim,Daehyeon Hong, Myeong Gyu Kim, Wooseon Choi, Taewon Min, Young-Min Kim,Yun-Hyuk Choi, ACSMaterials Letters , Volume5, Issue 4, Pages 1196–1201. (April 3, 2023)
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