Guo Xingyu, Li Yu, Xu Zhengrong, Liu Deng, Kong Aiguo, Liu Rui
Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education, School of Materials Science and Engineering, Tongji University, Shanghai, 201804, China.
School of Chemistry and Molecular Engineering, East China Normal University, Shanghai, 200241, China.
Small. 2025 Jan;21(4):e2408908. doi: 10.1002/smll.202408908. Epub 2024 Dec 5.
Hydrogen can be produced by electrolyzing urea aqueous solution under smaller overpotentials, owing to the lower thermodynamic potential of urea oxidation reaction (UOR) at anode than oxygen evolution reaction (OER). The efficient and selective electrocatalysts for UOR are crucial to achieve this. Herein, two NiS-based NiS/NiS and NiS/NiS heterojunctions with Ni cores embedding in nitrogen-doped carbon nanotubes (NiS/NiS- and NiS/NiS-Ni@NCNT) are demonstrated as efficient UOR electrocatalysts. The electrocatalytic UOR performance over heterojunctions is efficiently tuned by altering the electron transfer direction on their interfaces. NiS/NiS-Ni@NCNT with interface electrons transferring from NiS to NiS, delivers a 10 mA cm UOR current density in 1.0 m KOH with 0.5 m urea at 1.37 V, superior to NiS/NiS-Ni@NCNT with the electron transfer direction from NiS to NiS. Experimental and theoretical calculation results reveal that NiS/NiS Mott-Schottky heterojunctions facilitate the rapid in situ formation of NiOOH active species by removing electrons of NiS, and also accelerate the adsorption and conversion of urea molecules and key intermediates of CON at its interfaces. This work demonstrates an interface electron transfer direction tuning strategy on heterojunctions for harvesting high-performance UOR electrocatalysts.
由于阳极上尿素氧化反应（UOR）的热力学电位低于析氧反应（OER），因此可以在较小的过电位下通过电解尿素水溶液来制氢。用于UOR的高效且选择性的电催化剂对于实现这一点至关重要。在此，两种基于NiS的具有嵌入氮掺杂碳纳米管中的Ni核的NiS/NiS和NiS/NiS异质结（NiS/NiS-和NiS/NiS-Ni@NCNT）被证明是高效的UOR电催化剂。通过改变异质结界面上的电子转移方向，可以有效地调节其电催化UOR性能。界面电子从NiS转移到NiS的NiS/NiS-Ni@NCNT在含有0.5 m尿素的1.0 m KOH中，于1.37 V时提供10 mA cm的UOR电流密度，优于电子转移方向为从NiS到NiS的NiS/NiS-Ni@NCNT。实验和理论计算结果表明，NiS/NiS莫特-肖特基异质结通过去除NiS的电子促进了NiOOH活性物种的快速原位形成，并且还加速了尿素分子和CON关键中间体在其界面处的吸附和转化。这项工作展示了一种在异质结上调节界面电子转移方向以获得高性能UOR电催化剂的策略。
