Non-precious alloy encapsulated in nitrogen-doped graphene layers derived from MOFs as an active and durable hydrogen evolution reaction catalyst

Abstract

Non-precious metal based catalysts are emerging as the most promising alternatives to Pt-based ones for hydrogen evolution reaction (HER) due to their low cost and rich reserves. However, their low efficiency and stability due to inherent corrosion and oxidation in acid media are the main barriers blocking sustainable hydrogen production. Metal–organic frameworks, with both designable metal ion centers and organic ligands, are promising precursors for the one-step synthesis of metal/alloy@carbon composites for HER. Herein, we synthesized FeCo alloy nanoparticles encapsulated in highly nitrogen-doped (8.2 atom%) graphene layers by direct annealing of MOF nanoparticles at 600 °C in N₂. The catalyst shows a low onset overpotential (88 mV) and an overpotential of only 262 mV at 10 mA cm⁻². Besides, it exhibits an excellent long-term durability performance even after 10 000 cycles due to the protection of the graphene layers. Our density functional theory calculations reveal that the nitrogen dopants can provide adsorption sites for H* and the appropriate increase of nitrogen will decrease ΔG_H* for HER. Besides, the unique structure of the metal and graphene composites derived from MOFs can also decrease ΔG_H* thereby promoting the catalytic activity.