Highly active metallic nickel sites confined in N-doped carbon nanotubes toward significantly enhanced activity of CO2 electroreduction. (September 2019)

• Record Type: Journal Article
• Authors: Zheng, Wanzhen; Guo, Chenxi; Yang, Jian; He, Feng; Yang, Bin; Li, Zhongjian; Lei, Lecheng; Xiao, Jianping; Wu, Gang; Hou, Yang
• Is Part Of: Carbon. Volume 150(2019)
• Page Start: 52
• Page End: 59
• Publication Date: 2019-09
• Subjects: Carbon -- Periodicals; Carbone -- Périodiques; Koolstof; Toepassingen; Electronic journals; 546.681
• DOI: 10.1016/j.carbon.2019.04.112
• Languages: English
• ISSNs: 0008-6223

Abstract

Abstract: Carbon dioxide electroreduction (CO2 ER) still faces the challenges of low product selectivity, high overpotential, and high cost of electrocatalysts. Herein, we develop a low-cost and highly efficient precious-metal-free CO2 ER electrocatalyst, composed of Ni nanoparticles (NPs) with the size range of 50–100 nm, confined within N-doped carbon nanotubes (NCNTs) with the diameter of 100–200 nm (Ni@NCNTs). Benefitting from the confinement effect, the resulting 1D Ni@NCNTs hybrid exhibits an exceptional electrocatalytic activity and selectivity for CO production with a relatively positive onset potential of −0.3 V, low Tafel slope of 97 mV dec −1, and high Faradaic efficiency of 99.1%. The high selectivity of Ni@NCNTs for CO production during the CO2 ER is almost the best among all previously reported N-doped carbon based CO2 ER electrocatalysts. Experimental observations demonstrate that the confined Ni NPs inside NCNTs is a key step to promote the conversion of CO2 to CO. Density functional theory calculations reveal that the confinement effect of NCNTs can weaken the binding strengths between Ni NPs and *CO intermediates, thus improving the rate-limiting step of *CO desorption during the CO2 ER process. Further integration of 1D Ni@NCNTs electrocatalyst with a solar panel or two alkaline batteries enable highly active and sustainable CO2 ER and water splitting. Graphical abstract: Image 1 Highlights: A 1D Ni@NCNTs with confined the Ni NPs inside NCNTs was successfully fabricated. The hybrid exhibited superior electrochemical CO2 ER activity and selectivity. The confinement effect of Ni@NCNTs contributed to enhanced electrochemical performance. DFT calculations revealed the weak binding strengths between Ni NPs and *CO intermediates enhancing the kinetics in CO2 ER.