Understanding and manipulating the structural evolution of water oxidation electrocatalysts lays the foundation to finetune their catalytic activity. Herein, we present a synthesis of NiSe 2 -Ce 2 (CO 3 ) 2 O heterostructure and demonstrate the efficacy of interfacial Ce 2 (CO 3 ) 2 O in promoting the formation of catalytically active centers to improve oxygen evolution activity. In-situ Raman spectroscopy shows that incorporation of Ce 2 (CO 3 ) 2 O into NiSe 2 causes a cathodic shift of the Ni 2+ →Ni 3+ transition potential. Operando electrochemical impedance spectroscopy reveals that strong electronic coupling at heterogeneous interface accelerates charge transfer process. Furthermore, density functional theory calculations suggest that actual catalytic active species of NiOOH transformed from NiSe 2 , which is coupled with Ce 2 (CO 3 ) 2 O, can optimize electronic structure and decrease the free energy barriers toward fast oxygen evolution reaction (OER) kinetics. Consequently, the resultant NiSe 2 -Ce 2 (CO 3 ) 2 O electrode exhibits remarkable electrocatalytic performance with low overpotentials (268/304 mV @ 50/100 mA cm −2 ) and excellent stability (50 mA cm −2 for 120 h) in the alkaline electrolyte. This work emphasizes the significance of modulating the dynamic changes in developing efficient electrocatalyst.
Lixia Wang,Meilin Huang,Mingcheng Gao,Tayirjan Taylor Isimjan,Xiulin Yang
Effective control of strong electron interaction at heterogeneous interfaces is crucial for the creation of highly efficient and stable bifunctional catalysts for water splitting. In this work, we synthesized an urchin-like CoP–Ce2(CO3)2O catalyst on nickel foam (CoP–Ce2(CO3)2O/NF) via a facile hydrothermal and gas-phase phosphating process, which enhances active site exposure and improves catalytic reaction kinetics. Spectroscopy analysis reveals that the enhanced performance is due to the charge transfer between CoP and Ce2(CO3)2O and the unique urchin-like structure of the hybrid catalyst. The CoP–Ce2(CO3)2O/NF catalyst showed excellent hydrogen/oxygen evolution reaction (HER/OER) performance (η10 = 85.2 and 205.5 mV) and robust long-term stability in 1.0 M KOH. Additionally, the CoP–Ce2(CO3)2O/NF(+)||CoP–Ce2(CO3)2O/NF(−) electrolyzer required only a low cell voltage of 1.82 V to produce 100 mA cm−2 for overall water splitting, outperforming most previous catalysts. This work presents a strategy for interfacial engineering to improve the activity of bifunctional heterojunction electrocatalysts for overall water splitting.
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