Synthesis of heterogeneous mesoporous tetrafunctionalalized porphyrin-aliphatic diamine based framework encapsulated vanadium containing POM as electrocatalyst for hydrogen and oxygen evolution reactions

Abstract

An effective method for producing valuable fuels is electrocatalytic water dissociation, which involves the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). So, the development of new electrocatalysts for enhancing these processes is expected to minimize their overpotentials and increase the accessibility of their practical applications. The multifunctional properties of porphyrins and polyoxometalate (POMs) can help energy conversion devices. This study presents the synthesis of a novel metalloporphyrin and ethylenediamine-containing covalent organic framework (Et@PZn) and its successful incorporation of Lindqvist POM into the COF’s cavities, resulting in the LPOM@EtPZn framework. Both frameworks underwent comprehensive structural and morphological characterizations. The electrocatalytic performance in alkaline media was systematically assessed. Notably, LPOM@EtPZn exhibited a lower overpotential for HER and OER than Et@PZn indicating its superior kinetics, which was further confirmed by Tafel slope values of about 115 mV dec−1 and 55 mV dec−1 for LPOM@EtPZn which found better than that of Et@PZn of about 161 mV dec−1 and 108 mV dec−1 for HER and OER respectively. LPOM@EtPZn also showed best overpotential than standard 20 %Pt/C electrode for HER. Electrochemical investigations, including electroactive surface area (ECSA) measurement and electrochemical impedance spectroscopy (EIS), also confirmed the charge transfer advantages of LPOM@EtPZn. These findings underscore the potential of LPOM@EtPZn as a versatile and efficient electrocatalyst for diverse applications, in advancing renewable energy technologies.