biostudies-literaturePeng CKMinistry of Science and Technology, TaiwanMinistry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)529https://www.ebi.ac.uk/biostudies/studies/S-EPMC9892518biostudies-literatureUnknown14(1)The production of ecologically compatible fuels by electrochemical water splitting is highly desirable for modern industry. The Zhang-Rice singlet is well known for the superconductivity of high-temperature superconductors cuprate, but is rarely known for an electrochemical catalyst. Herein, we observe two steps of surface reconstruction from initial catalytic inactive Cu¹⁺ in hydrogen treated Cu₂O to Cu²⁺ state and further to catalytic active Zhang-Rice singlet state during the oxygen evolution reaction for water splitting. The hydrogen treated Cu₂O catalyst exhibits a superior catalytic activity and stability for water splitting and is an efficient rival of other 3d-transition-metal catalysts. Multiple operando spectroscopies indicate that ZhanNature communicationsZhang-Rice singlets state formed by two-step oxidation for triggering water oxidation under operando conditions.PMC9892518111‐2634‐F‐A49‐007111-2634-F-A49-007111-2112-M-213-012Li JFQian ZPeng CKLin YCChen SYHu ZChiang CLLin YGChen CTDong CLHuang YCfalseZhang-Rice singlets state formed by two-step oxidation for triggering water oxidation under operando conditions.The production of ecologically compatible fuels by electrochemical water splitting is highly desirable for modern industry. The Zhang-Rice singlet is well known for the superconductivity of high-temperature superconductors cuprate, but is rarely known for an electrochemical catalyst. Herein, we observe two steps of surface reconstruction from initial catalytic inactive Cu¹⁺ in hydrogen treated Cu₂O to Cu²⁺ state and further to catalytic active Zhang-Rice singlet state during the oxygen evolution reaction for water splitting. The hydrogen treated Cu₂O catalyst exhibits a superior catalytic activity and stability for water splitting and is an efficient rival of other 3d-transition-metal catalysts. Multiple operando spectroscopies indicate that Zhan2023-01-01T00:00:00Z2023 Feb2026-07-16T20:12:01.166Z2025-04-06T02:21:05.278ZS-EPMC98925183672586410.1038/s41467-023-36317-2