Gold-bridged LaCo1−xAuxO3 perovskite nanocomposite for synergically enhanced electrochemical hydrogen storage

Abstract

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 ratio of 1:3 achieves an impressive capacity of 2230 mAh g⁻¹, surpassing the cumulative capacity of the individual components. Further, our calculations display that Au substitution largely improves the hydrogen absorption in the bulk rather than surface, enriches DOS near the Fermi level, and enhancing 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.