In situ activation of atomically dispersed Rh in layered double hydroxides for efficient hydrogen evolution in acidic conditions

Enhancing the catalytic efficiency and cost-effectiveness of hydrogen evolution reaction (HER) catalysts is essential for advancing sustainable energy systems. This study presents an innovative strategy to achieve high-density atomic dispersion of Rh by synthesizing Rh-containing magnesium-aluminum layered double hydroxides (Rh–MgAl LDH) and using it to derive an efficient HER catalyst. High-angle annular dark-field scanning transmission electron microscopy images and density functional theory calculations confirm the thermodynamic stability of Rh in an atomically dispersed state within the LDH structure. During the HER process, the synthesized Rh–MgAl LDH is activated through in situ rearrangement, transforming into an Rh catalyst that exhibits HER performance comparable with that of commercial Rh catalysts. Notably, it achieves an overpotential of 31 mV at a current density of 10 mA cm⁻² and a Tafel slope of 62.5 mV dec⁻¹ under acidic conditions. Additionally, at high current densities, it exhibits a low overpotential of 193 mV, outperforming commercial Rh catalysts. The activated Rh catalyst maintains stable catalytic activity for over 20 h. It demonstrates a lower overpotential than that of commercial Pt/C catalysts at lower current densities, highlighting its potential for integration into solar-driven hydrogen production systems. This research offers valuable insights into the design and application of atomically dispersed catalysts within LDH supports, contributing to the development of next-generation electrocatalysts for sustainable hydrogen production.