A cobalt harnessed phenanthroline and triphenylamine-based conjugated mesoporous polymer designed by a donor–acceptor approach for trifunctional electrocatalysis

Abstract

A conjugated mesoporous polymer with a donor–acceptor approach (TBPA-phen) is synthesized via tetrakis(triphenylphosphine)palladium-catalyzed Sonogashira coupling and is exploited for in situ modification with cobalt (Co@TBPA-phen). The polymers exhibit a charge-separated state and semiconducting behavior at room temperature. The microscopy images reveal spherical morphology and multipoint Brunauer–Emmett–Teller analysis confirms the presence of mesoporosity (d = 2.6–4.5 nm). TBPA-phen exhibits significant electrochemical activity for the oxygen reduction reaction (ORR) with a low onset potential of 0.80 V vs. the reversible hydrogen electrode (RHE) and hydrogen evolution reaction (HER) with an overpotential of −486 mV @10 mA cm⁻². But merely 6.3 wt% Co stabilized Co@TBPA-phen drives the oxygen evolution reaction (OER) at an overpotential of 480 mV @10 mA cm⁻² along with the ORR (E_onset = 0.82 V vs. RHE) and HER (−335 mV @10 mA cm⁻²) at reduced overpotentials. Our density functional theory computations disclose the descriptor for every reaction along with validating that facilely synthesized polymers are exquisite donor–acceptor pairs. The natural bond orbital study provides orbital interactions and charge transfer in the ORR and OER and supports cobalt stabilized in Co@TBPA-phen in Co(0) and Co(II) states. A rechargeable Zn–air battery bestows an open circuit voltage of 1.51 V, a specific capacity of 723 mA h g⁻¹, and a significant discharge potential of 1.2 V with no change in the voltage window of 0.75 V for up to 108 cycles. The study unravels strategically designed conjugated mesoporous polymers as efficient trifunctional electrocatalysts for electrochemical energy storage applications.