Carbon core–shell Pt nanoparticle embedded porphyrin Co-MOF derived N-doped porous carbon for the alkaline AEM water electrolyzer application

Abstract

Industrial clean hydrogen (H₂) production using efficient and durable electrocatalysts is an essential goal for developing future renewable energy systems. Herein, we report the synthesis of carbon core–shell platinum (Pt) nanoparticles embedded in porphyrin cobalt (Co) metal–organic framework (MOF) derived nitrogen-doped porous carbon (Pt@Co-NPC) via pyrolysis of Pt–aniline complex/Co-MOF at 600–800 °C for the H₂ evolution reaction (HER). In 1.0 M KOH electrolyte medium, the resulting Pt@Co-NPC-800 electrocatalyst achieved a low overpotential of 34 mV to reach 10 mA cm⁻², together with a Tafel slope of 42.72 mV dec⁻¹, and good stability for more than 96 h at a current density of 100 and 200 mA cm⁻² compared to commercial Pt nanoparticles with a carbon support (Pt/C). Notably, high surface area (263.40 m² g⁻¹) porous carbon materials with uniformly distributed Pt@Co nanostructures provided better HER electrocatalytic activity. Moreover, density functional theory (DFT) calculations reveal that the improved HER activity of the Pt@Co-NPC-800 electrocatalyst arises from the enhanced synergetic effect between the Pt and Co, which induces the favourable Gibbs free-energy value of −0.120 eV for H* adsorption in the Pt active site. Besides, the fabricated anion exchange membrane water electrolyzer (AEMWE) achieved a current density of ∼1.32 A cm⁻² at 2.34 V_cell in 1.0 M KOH, 60 °C. The designed Pt@Co-NPC-800 electrocatalyst provides a new direction to make efficient AEMWEs.