Abstract
The 2D conductive metal–organic frameworks (MOFs) are expected to be an ideal electrocatalyst due to their high utilization of metal atoms. Exploring a new conjugated ligand with extra active metallic center can further boost the structural advantages of conductive MOFs. In this work, hexaiminohexaazatrinaphthalene (HAHATN) is employed as a conjugated ligand to construct bimetallic sited conductive MOFs (M23(M13∙HAHATN)2) with an extra M–N2 moiety. Density functional theory (DFT) calculations demonstrate that the 2D conjugated framework renders M23(M13∙HAHATN)2 a high electric conductivity with narrow bandgap (0.19 eV) for electron transfer and a favorable in‐plane porous structure (2.7 nm) for mass transfer. Moreover, the metal atom at the extra M–N2 moiety has a higher unsaturation degree than that at M–N4 linkage, resulting in a stronger ability to donate electrons for enhancing electroactivity. These characteristics endow the new conductive MOFs with an enhanced electroactivity for hydrogen evolution reaction (HER) electrocatalysis. Among the series of M23(M13∙HAHATN)2 MOF, Ni3(Ni3∙HAHATN)2 nanosheets with the optimal structure exhibit a small overpotential of 115 mV at 10 mA cm−2, low Tafel slope of (45.6 mV dec−1), and promising electrocatalytic stability for HER. This work provides an effective strategy for designing conductive MOFs with a favorable structure for electrocatalysis.
Highlights
The products in each synthetic process were preliminarily confirmed through nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) technology (Figures S1–S5, Supporting Information)
A series of hydrogen evolution reaction (HER) electrocatalytic tests confirm the prophecy of theory in experimental
The optimal Ni3(Ni3∙HAHATN)2 nanosheets exhibit a remarkably activity enhancement for HER compared to traditional Ni3(HITP)2 conductive metal–organic frameworks (MOFs)
Summary
Various nickel precursors including Ni-based MOFs are usually used to construct efficient HER electrocatalysts due to their low cost and high activity, including Ni-based MOFs.[34,35] In this work, we employ Ni3∙HAHATN as a conjugated ligand to construct conductive Ni3(Ni3∙HAHATN) MOFs via a synthetic step and two consecutive coordination reactions (Scheme 1). Hydrogen absorption in Ni–N4 linkage makes the framework of Ni3(Ni3∙HAHATN) bending, which breaks the rigid 2D structure These results show the Ni–N2 moieties in Ni3(Ni3∙HAHATN) is more active for HER than Ni–N4 linkages in conductive MOFs. Meantime, the ΔGH* of M1–N2 center in M23(M13∙HAHATN) slabs exhibits a similar regularity as the electrochemical results: Ni–N2 in Ni3(Ni3∙HAHATN) (−0.12 eV) > Co–N2 in Ni3(Co3∙HAHATN) (−0.29 eV) > Cu–N2 in Ni3(Cu3∙HAHATN) (−0.61 eV) > Cu–N2 in Cu3(Cu3∙HAHATN) (−0.64 eV). The ΔGH* of M1–N2 center in M23(M13∙HAHATN) slabs exhibits a similar regularity as the electrochemical results: Ni–N2 in Ni3(Ni3∙HAHATN) (−0.12 eV) > Co–N2 in Ni3(Co3∙HAHATN) (−0.29 eV) > Cu–N2 in Ni3(Cu3∙HAHATN) (−0.61 eV) > Cu–N2 in Cu3(Cu3∙HAHATN) (−0.64 eV) According to these results, M23(M13∙HAHATN) is expected to be an ideal coordinated structure toward electrocatalysis, which proves our design concept of new conductive MOFs for electrocatalysis is feasible. The results reveal that the rigid conjugated coordinated structure makes Ni3(Ni3∙HAHATN) possess excellent durability during HER process
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
