Cobalt(ii) ions and cobalt nanoparticle embedded porous organic polymers: an efficient electrocatalyst for water-splitting reactions

Abstract

Development of a highly efficient electrocatalyst for the water-splitting reaction is essential and in this regard, the use of earth-abundant metal catalysts offers several advantages such as improved performance, cost-efficiency, etc. Recent studies have shown that the fabrication of transition metal/metal oxide nanoparticle supported carbon materials exhibit similar performances to that of bare metal/metal oxide nanoparticles. Herein, we report the preparation of an ethylenediamine interconnected triazine based porous organic polymer (EPOP) modified with Co²⁺ (Co-EPOP) and Co nanoparticles (Co-EPOP-300, Co-EPOP-500 and Co-EPOP-HT) via anchoring under different conditions. The amine groups on the EPOP polymer were used as ligands and as stabilizers for Co²⁺ and Co nanoparticles respectively. XRD and TEM analysis indicated that the Co-NPs covered a homogeneous polymer matrix. The electrocatalytic activities of Co²⁺/CoNP modified POPs were evaluated under standard OER and HER conditions and were compared with that of Co-NPs without polymer support. Amongst the electrocatalysts, the Co-EPOP (Co²⁺ anchored EPOP) sample exhibited bifunctional activity towards both the OER and HER with onset potentials of 1.638 and −0.173 V respectively. Further, the Co-EPOP catalyst showed lower Tafel slope values compared to other catalysts. Both OER and HER performances are comparable with those of reported Co based nanocatalytic systems.