Highly Efficient Au₁Pd Single-Atom Alloy Catalyzing Reversible Formate/Bicarbonate Interconversion: Proof-of-Concept...

Reversible hydrogen storage via formate/bicarbonate cycles is a promising strategy for large-scale hydrogen storage, while the lack of highly efficient catalysts for reversible interconversion remains a critical bottleneck. Herein, we report an amine-modified activated carbon-supported Au₁Pd single-atom alloy (SAA) catalyst (Au₁Pd₂₀/AC-NH) as the key breakthrough to address this challenge, and further demonstrate its proof-of-concept application in a novel "Formate-Salt Cavern Hydrogen Storage System". Featuring atomically dispersed Au promoters anchored on Pd nanoparticles, Au₁Pd₂₀/AC-NH boosts Pd's intrinsic activity remarkably. Under near-ambient conditions, it exhibits exceptional turnover frequencies (TOFs, based on total active metal) of 4568 h^-1 for dehydrogenation (80°C, 1 bar, 1 M HCOOK) and 77 h^-1 for hydrogenation (30°C, 1 bar, 1.5 M KHCO₃). Specifically, in the formate dehydrogenation reaction, the Au₁Pd₂₀/AC-NH catalyst exhibits a 45% higher initial TOF value at a conversion of 20% compared with monometallic Pd/AC-NH; meanwhile, its hydrogenation activity is increased by 34%. These values are among the highest reported under similar reaction conditions. Mechanistic analysis reveals that the superior catalytic performance stems from the Au₁Pd SAA effect and synergistic interaction with surface ─NH─ groups, which collectively facilitate H₂ dissociation and reactant adsorption. By establishing an efficient catalytic strategy and providing critical proof-of-concept, this work paves a viable pathway for large-scale hydrogen storage.