ZIF-derived 3D carbon nanosheet/nanotube framework with encapsulated CoNi nanoparticles for efficient LOHC hydrogen storage

Abstract

Liquid organic hydrogen carrier (LOHC) systems require efficient, low-cost catalysts for scalable hydrogen storage. Here, a reusable CoNi bimetallic catalyst was developed through one-step reductive pyrolysis of ZIF-67-L, forming CoNi alloy nanoparticles embedded in a 3D carbon nanosheet/nanotube (CNS/CNT) heterostructure. Using N-ethylcarbazole (NEC) as a model compound, the optimized catalyst enables rapid hydrogenation (5.72 wt% H₂ uptake at 150 °C, 8 MPa in 80 min) and dehydrogenation (5.64 wt% H₂ release at 220 °C, 0.1 MPa), with high recyclability over seven cycles. The CNS/CNT facilitates electron transport, enhances active site exposure, and provides a high surface area. Combined XPS and DFT results reveal that the synergy between the CNS/CNT architecture and CoNi alloying modulates the electronic environment of Co⁰ sites, reduces the energy barrier for H₂ dissociation, and improves catalytic performance. This study provides new insights into the design of highly active and stable non-noble metal catalysts for LOHC systems to achieve reversible hydrogen storage.