Ambient Hydrogen Storage and Release Using CO₂ and an l‑Arginine-Functionalized PdAu Catalyst via pH Control

Formic acid (FA)/formate as a promising liquid organic hydrogen carrier exhibits great potential for future energy supplies. However, FA/formate-based hydrogen storage and release, which can be operated under ambient conditions, is challenging but attractive. Here, we report an ambient hydrogen storage and release process that uses the acidity and alkalinity of the reaction solution to control hydrogen production or consumption via an l-arginine-functionalized active carbon-supported PdAu alloy catalyst (PdAu/AC-LA). By regulating the LA loading and Pd/Au ratio, we obtain the optimal catalytic activity with turnover frequency (TOF) of 1760 h^–1 for FA dehydrogenation under acidic conditions and 138 h^–1 for CO₂ hydrogenation under alkaline conditions. Comprehensive characterizations, including X-ray photoelectron spectroscopy (XPS), CO₂ temperature-programmed desorption (CO₂-TPD), and HCOO^– adsorption experiments, reveal that the synergistic effect between PdAu alloy and strongly basic l-arginine enhances catalytic activity by regulating the adsorption of reactants. Our work, as a successful example of FA/formate-based hydrogen storage and release under ambient conditions, may aid putting the safe and energy-saving use of hydrogen into practice.