Fe-phthalocyanine derived highly conjugated 2D covalent organic framework as superior electrocatalyst for oxygen reduction reaction

Anuj Kumar; Mohd Ubaidullah; Bidhan Pandit; Ghulam Yasin; Ram K Gupta; Guoxin Zhang

doi:10.1186/s11671-023-03890-w

Fe-phthalocyanine derived highly conjugated 2D covalent organic framework as superior electrocatalyst for oxygen reduction reaction

Discov Nano. 2023 Sep 4;18(1):109. doi: 10.1186/s11671-023-03890-w.

Authors

Anuj Kumar¹, Mohd Ubaidullah², Bidhan Pandit³, Ghulam Yasin⁴, Ram K Gupta⁵, Guoxin Zhang⁶

Affiliations

¹ Nano-Technology Research Laboratory, Department of Chemistry, GLA University, Mathura, Uttar Pradesh, 281406, India.
² Department of Chemistry, College of Science, King Saud University, 11451, Riyadh, Saudi Arabia.
³ Department of Materials Science and Engineering and Chemical Engineering, Universidad Carlos III de Madrid, Avenida de La Universidad 30, 28911, Leganés, Madrid, Spain.
⁴ Institute for Advanced Study, Shenzhen University, Shenzhen, 518060, Guangdong, China. anujkumar9791@gmail.com.
⁵ Department of Chemistry, National Institute for Materials Advancement, Pittsburg State University, Pittsburg, KS, 66762, USA. anuj.kumar@gla.ac.in.
⁶ Department of Electrical Engineering and Automation, Shandong University of Science and Technology, Qingdao, 266590, Shandong, People's Republic of China.

Abstract

Although porphyry systems like metallo-phthalocynine are recognized as promising molecular models for electrocatalytic oxygen reduction reaction (ORR), their poor durability and methanol tolerance are still challenges and need improvement before being considered for practical applications. Herein, we successfully designed and constructed a Fe-phthalocyanine-derived highly conjugated 2D covalent organic framework (2D FePc-COF), using octa-amino-Fe-phthalocyanine (OA-FePc) and cyclohexanone as precursors. The prepared 2D FePc-COF was characterized via multiple analytic techniques. The electrochemical studies indicated that prepared 2D FePc-COF was far more superior to OA-FePc and 20% Pt/C, displaying anodic shift of 100 and 50 mV (vs RHE) in formal potential, respectively. Moreover, this catalyst also demonstrated excellent methanol tolerance and durability (over 10,000 CV cycles). Theoretical investigations revealed that due to extended conjugation and elimination of electron donating groups (-NH₂), the shifting of dz²-orbital (Fe) energy took nearer to π*-orbital (O₂), allowing optimum coupling of both the orbitals, thereby enhancing 4e^- ORR. This work demonstrates the art of molecular design, aiming at improving catalytic activity of macrocyclic molecular systems towards ORR.

Keywords: Electrocatalytic activity; Fe-phthalocyanine; Molecular catalysts; Oxygen reduction reaction.