A porous Co3Mo3N/N-doped carbon electrocatalyst derived from Mo–Co MOFs for the electrochemical hydrogen evolution reaction

Abstract

The development of non-noble metal–organic framework (MOF)-derived bimetallic transition metal nitride (TMN) electrocatalysts for the hydrogen evolution reaction (HER) is a challenging task. Previously, Pt-based electrocatalysts were considered potential noble candidates for the HER owing to their excellent electrocatalytic activity. However, composite electrocatalysts based on the synergy of bimetals and porous carbon have demonstrated the enhanced electrical conductivity and catalytic activity. Herein, a porous Co₃Mo₃N/nitrogen-doped carbon (NC) composite electrocatalyst derived from Mo–Co MOFs was prepared via co-precipitation and pyrolysis at different temperatures (700, 800 and 900 °C), and the samples are denoted as CMN700, CMN800, and CMN900. In this study, the CMN900 catalyst exhibited a porous nanoparticle morphology and improved electron/mass transport, leading to the generation of abundant reactive active sites for the HER. Furthermore, the electrochemical nature of the optimized electrocatalyst was studied using 1 M alkaline potassium hydroxide (KOH) electrolyte solution. The synthesized Co₃Mo₃N/NC electrocatalyst required a low overpotential of 125 mV to attain a low current density of 10 mA cm⁻² and a small Tafel slope of 98.49 mV dec⁻¹. The synergistic performance of the Co and Mo sites in nitrogen-doped carbon achieved good electrochemical active surface area value (92.5 cm²) and charge transfer resistance value (2.20 Ω). Moreover, the durability of the prepared electrocatalyst was verified by chronoamperometry analysis at the low current density for a prolonged duration, demonstrating its good stability and suitability as an electrocatalyst for sustainable hydrogen energy production.