Confining electrocatalytic nickel complex in metal-organic frameworks for efficient hydrogen-evolution

Growing energy demand has necessitated the development of an active, stable, and low-cost catalytic material for hydrogen production. Therefore, cavity-or pore-directed chemical transformation is a promising approach for improving catalyst stability and durability via pore confinement. In this work, we investigate the confinement effect of metal-organic frameworks (MOFs) in the presence of a Ni-based molecular catalyst for the hydrogen evolution reaction (HER). We choose stable and porous Zr-based MOFs (NU-1000 (1) and MOF-808 (2)) and a Nibased square-planar complex (Ni-ABT). The Ni-ABT was incorporated inside the pores of MOFs 1 and 2, and the integrated materials [Ni-ABT@NU-1000 (1 '), Ni-ABT@MOF-808 (2 ')] were successfully characterized by various instrumental methods. Electrochemical results revealed that the integrated materials 1 ' and 2 ' showed enhanced HER activity in phosphate buffer solution, significantly improving their onset potential compared with their pristine MOFs. Because of the pore confinement, the Ni-ABT catalyst is stabilized by 1, leading to a higher HER activity with long-term durability. We demonstrate the improved catalyst stability, enhanced HER performance, and long-time durability of the model catalyst by protecting it through the confinement effect of MOFs. This work provides new insights into the electrocatalytic reaction mechanism of HER via MOF confinement.