Carbon dioxide mediated, reversible chemical hydrogen storage using a Pd nanocatalyst supported on mesoporous graphitic carbon nitride

Reversible, carbon dioxide mediated chemical hydrogen storage was first demonstrated using a heterogeneous Pd catalyst supported on mesoporous graphitic carbon nitride (Pd/mpg-C sub(3)N sub(4)). The Pd nanoparticles were found to be uniformly dispersed onto mpg-C sub(3)N sub(4) with an average size of 1.7 nm without any agglomeration and further exhibit superior activity for the dehydrogenation of formic acid with a turnover frequency of 144 h super(-1) even in the absence of external bases at room temperature. Initial DFT studies suggest that basic sites located at the mpg-C sub(3)N sub(4) support play synergetic roles in stabilizing reduced Pd nanoparticles without any surfactant as well as in initiating H sub(2)-release by deprotonation of formic acid, and these potential interactions were further confirmed by X-ray absorption near edge structure (XANES). Along with dehydrogenation, Pd/mpg-C sub(3)N sub(4) also proves to catalyze the regeneration of formic acid viaCO sub(2) hydrogenation. The governing factors of CO sub(2) hydrogenation are further elucidated to increase the quantity of the desired formic acid with high selectivity.