Chen Hongyu, Xu Yongsheng, Li Xiaojie, Ma Qing, Xie Delong, Mei Yi, Wang Guojing, Zhu Yuanzhi
Faculty of Chemical Engineering, Yunnan Provincial Key Laboratory of Energy Saving in Phosphorus Chemical Engineering and New Phosphorus Materials, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China.
School of Chemistry and Chemical Engineering/State Key Laboratory Incubation Base for Green Processing of Chemical Engineering, Shihezi University, Shihezi, 832000, China.
Adv Sci (Weinh). 2024 Aug;11(31):e2402889. doi: 10.1002/advs.202402889. Epub 2024 Jun 18.
The inefficiency of electrocatalysts for water splitting in neutral media stems from a comprehensive impact of poor intrinsic activity, a limited number of active sites, and inadequate mass transport. Herein, hierarchical ultrathin NiCoSe nanosheets are synthesized by the selenization of NiCoO porous nanoneedles. Theoretical and experimental investigations reveal that the intrinsic hydrogen evolution reaction (HER) activity primarily originate from the NiCoSe, whereas the high oxygen evolution reaction (OER) performance is related to the NiCoOOH due to the structural reconstruction. The abundant Se and O vacancies introduced by atomically thin nanostructure modulate the electronic structure of NiCoSe and NiCoOOH, thereby improving the intrinsic HER and OER activities, respectively. COMSOL simulation demonstrate the edges of extended nanosheets from the main body significantly promote the charge aggregation, boosting the reduction and oxidation current during HER/OER process. This charge aggregation effect notably exceeds the tip effect for the nanoneedle, highlighting the unique advantage of the hierarchical nanosheet structure. Benefiting from abundant vacancies and unique nanostructure, the hierarchical ultrathin nanosheet simultaneously improve the thermodynamics and kinetics of the electrocatalyst. The optimized samples display an overpotential of 92 mV for HER and 214 mV for OER at 100 mA cm, significantly surpassing the performance of currently reported HER/OER catalysts in neutral media.
中性介质中用于水分解的电催化剂效率低下，源于本征活性差、活性位点数量有限和传质不足的综合影响。在此，通过对NiCoO多孔纳米针进行硒化合成了分级超薄NiCoSe纳米片。理论和实验研究表明，本征析氢反应（HER）活性主要源于NiCoSe，而高析氧反应（OER）性能则与结构重构产生的NiCoOOH有关。原子级薄的纳米结构引入的大量Se和O空位分别调节了NiCoSe和NiCoOOH的电子结构，从而提高了本征HER和OER活性。COMSOL模拟表明，从主体延伸出的纳米片边缘显著促进了电荷聚集，提高了HER/OER过程中的还原和氧化电流。这种电荷聚集效应明显超过了纳米针的尖端效应，突出了分级纳米片结构的独特优势。得益于丰富的空位和独特的纳米结构，分级超薄纳米片同时改善了电催化剂的热力学和动力学。优化后的样品在100 mA cm下HER的过电位为92 mV，OER的过电位为214 mV，显著超过了目前报道的中性介质中HER/OER催化剂的性能。
