Acetylene-linked triaryl 2D covalent organic frameworks as electrocatalysts for hydrogen evolution

Light main-group elements are so abundant in the Earth’s crust that materials based on them are generally cost-effective and suitable for mass production. A catalyst made of these elements for the hydrogen evolution reaction (HER) may help in triggering the hydrogen economy. In this context, metal-free 2D covalent organic frameworks (COFs) are promising for electrocatalytic applications in view of their remarkable structural, electronic and compositional versatility. Here, we use density functional theory calculations to build phase diagrams, activity plots and fit machine learning models to assess the HER performance of a class of 2D COFs based on acetylene-linked triaryl centers. We have screened over 40 2D COFs with a range of nodal centers and aryl ring substituents. We find that the HER activity of our 2D COFs can be described in terms of the oxidation state of the substituents on the aryl rings and the ionization energy or molecular weight of the most stable isotope of the triaryl nodal centers. Indeed, we find that materials with B and C nodal centers are more active for the HER than those containing CH and N centers. In turn, varying the aryl ring substituents we predict that the -BH 2 substituent could lead to 2D-COFs with remarkably high HER activities. • We study 2D COFs built from triaryl units and diacetylenic linkers for the HER • The triaryl units can have different nodal centers and peripheral substituents • The degree of hydrogenation of the 2D COFs under HER conditions is ascertained • HER activity depends on substituent oxidation state and center ionization energy • The most active 2D COFs for the HER have B centers and -BH 2 substituents