Mixed-Metal c-IRMOF-10 Metal–Organic Frameworks for Enhanced Visible-Light Hydrogen Evolution Reaction

Abstract

Metal–organic frameworks (MOFs) are promising photocatalysts for solar-driven hydrogen production, but their practical application is often limited by wide band gaps and insufficient visible-light utilization. In this work, mixed-metal Cu-substituted c-IRMOF-10 frameworks were systematically investigated for the hydrogen evolution reaction (HER) using density functional theory (DFT + U) and ab initio molecular dynamics (AIMD) simulations. Partial substitution of Zn or Cd nodes with Cu (25–50%) significantly narrows the band gap from 4.02 to 3.17 eV for Zn-based systems and from 3.79 to 3.19 eV for Cd-based systems, resulting in enhanced visible-light absorption with optical coefficients reaching 2.5 × 105 cm–1. AIMD simulations confirm the structural stability of the Cu-containing frameworks. The calculated band-edge positions exhibit favorable alignment with the redox potentials required for photocatalytic water splitting, while Cu-induced charge redistribution promotes charge separation and transfer. Among the investigated compositions, Cu0.50Cd0.50@c-IRMOF-10 exhibits the highest predicted hydrogen yield of 55.95 μmol g–1, compared with 16.82 μmol g–1 for Cu0.50Zn0.50@c-IRMOF-10. Furthermore, Gibbs free energy calculations reveal nearly thermoneutral hydrogen adsorption at the Cu-M (M = Zn or Cd) bridge sites (ΔGH* ≈ 0.03–0.06 eV), indicating highly active HER centers. These findings demonstrate that Cu incorporation effectively enhances light harvesting, charge transfer behavior, and HER activity, providing valuable design principles for the development of high-performance MOF-based photocatalysts for hydrogen production.