Gold-bridged LaCo_1−xAu_xO₃ perovskite nanocomposites for synergically enhanced electrochemical hydrogen storage

Perovskite oxides, with the general formula ABO₃, have emerged as promising candidates for electrochemical hydrogen storage under ambient conditions due to their spacious unit cells and high electrical conductivity, offering a sustainable approach to energy conversion and storage. Here, we synthesize sub-micron LaCoO₃ (LCO) and Au-incorporated LaCoO₃ (0–2.0 at% Au:LCO) perovskite particles. Experimental characterizations and theoretical calculations reveal that Au is partially doped into the LCO lattice, while the remaining Au nanoparticles are uniformly distributed on the surface with an average size of 5–10 nm. Electrochemical analysis shows that 0.5% Au:LCO achieves the highest hydrogen storage capacity of 1264 mAh g⁻¹. Furthermore, the combination of 0.5% Au:LCO with partially reduced graphene oxide (GO) as a more conductive matrix yields nanocomposites that demonstrate significantly enhanced performance. Notably, the optimized nanocomposite electrode achieves an impressive capacity of 2230 mAh g⁻¹, surpassing the cumulative capacity of the individual components. Our calculations show that Au substitution largely improves the hydrogen absorption in the bulk rather than at the surface, enriches the DOS near the Fermi level, and enhances the HER barrier. This synergistic enhancement is attributed to the dual role of Au in modifying the perovskite structure and bridging interactions within the nanocomposite.