Tuning the Electrochemical Properties of Polymeric Cobalt Phthalocyanines for Efficient Water Splitting

Abstract Polymeric metal phthalocyanines have great potential as electrocatalysts, yet their incorporation on a current collector without losing the activity of metal centers remains a challenge. Herein, a new strategy for preparing a series of polymeric cobalt phthalocyanines containing S linkers ( p CoPc‐1) or SO 2 linkers ( p CoPc‐2) and their tunable electrochemical properties are reported. The p CoPcs coated on various substrates show favorable electrocatalytic activities toward oxygen and hydrogen evolution reactions (OER and HER). Particularly, the p CoPc‐1 layer on Co 3 O 4 nanosheet arrays exerts a cooperative effect enhancing both the OER and HER performances, and the subsequent phosphorization (P@ p CoPc‐1/Co 3 O 4 |CC) significantly boosts the HER performance with enhanced hydrophilicity and conductivity. The high permeability and stability reinforcement of the p CoPc‐1 layer allow the phosphorization of underlying Co 3 O 4 to CoP without degradation, which remarkably enhances OER and HER performances as manifested by low overpotentials of 320 and 120 mV at 10 mA cm −2 , respectively. When engaged as a bifunctional electrocatalyst for the overall water splitting, the P@ p CoPc‐1/Co 3 O 4 |CC requires a low cell voltage of 1.672 V at 10 mA cm −2 , showing long‐term durability and mechanical robustness. This study demonstrates the collaborative catalytic role of polymeric macrocyclic compounds that offers versatile tunability and stability for various electrocatalytic reactions.