Nickel polyphthalocyanine with electronic localization at the nickel site for enhanced CO2 reduction reaction

• Published in: Applied catalysis. B, Environmental Environmental, 2022-06, Vol.306, p.121093, Article 121093
• Main Authors: Chen, Kejun, Cao, Maoqi, Ni, Ganghai, Chen, Shanyong, Liao, Hanxiao, Zhu, Li, Li, Hongmei, Fu, Junwei, Hu, Junhua, Cortés, Emiliano, Liu, Min
• Format: Article
• Language: English
• Subjects: Active sites; Adsorption; Carbon dioxide; Carbon nanotubes; Catalysts; Catalytic activity; Chemical reduction; CO2 reduction reaction; Conjugation; Electrocatalysis; Electronic localization; Localization; Nanotechnology; Nanotubes; Nickel; Nickel polyphthalocyanine; Ni−N4 site; Selectivity
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2022.121093

Nickel phthalocyanine (NiPc) can be at first glance a compelling catalyst for CO2 reduction reaction (CO2RR) because of its Ni–N4 site. Unfortunately, the pristine NiPc possesses a low catalytic activity resulting from the poor CO2 adsorption and activation capabilities of the electron-deficiency Ni site. Herein, we develop nickel polyphthalocyanine (NiPPc) with extended conjugation to tailor the electronic density at the Ni active site. The enlarged π conjugation of NiPPc evokes the d-electrons localization, increasing the electronic density at the Ni site, which enhances its CO2 adsorption and activation. Consequently, NiPPc supported on carbon nanotubes (NiPPc/CNT) in a flow cell delivers an excellent activity of −300 mA cm−2 for CO2RR with the CO selectivity of 99.8%, which is much higher than that of NiPc dispersed on carbon nanotubes. NiPPc/CNT exhibits an outstanding stability for CO2RR of more than 30 h at a current density of −100 mA cm−2 with an ultrahigh selectivity for CO, exceeding 99.7%. This work showcases a new way of tuning the electronic density of catalytic sites. This work reports a strategy for constructing a conjugated polymer structure to regulate the electron density at the catalytic active site, Ni in this case. The conjugated Ni polyphthalocyanine with the electronic localization at the nickel and supported on a carbon nanotube demonstrates an enhanced CO2 adsorption and activation, boosting the CO2 reduction reaction. [Display omitted] •The enlarged π conjugation of NiPPc evokes the d-electrons localization to increasing the electronic density at Ni site.•The electronic localization at Ni site can enhance its CO2 adsorption and activation.•NiPPc/CNT delivers an outstanding performance for CO2RR with a superior stability and CO selectivity.