UiO-67-bipy@CuII formate as a catalyst precursor for the production of hydrogen gas from formic acid under mild conditions.

The growing demand for hydrogen as a clean energy carrier has intensified interest in efficient and sustainable generation strategies. Herein, we report a Cu-functionalised UiO-67-bipy catalyst precursor for hydrogen production via the mild decomposition of formic acid. Prior density functional theory (DFT) studies on model CuI-phenanthroline/bipyridine systems identified a two-step catalytic cycle involving CuI hydrides and CuI formates. Motivated by these findings, a UiO-67-bipy framework was post-synthetically modified with CuII formate to yield UiO-67-bipy@CuII formate, which upon treatment with l-ascorbic acid generate a catalytically active species. ICP-OES, IR spectroscopy, EPR spectroscopy and PXRD support incorporation of CuII formate with retention of the UiO-67-bipy framework. Catalytic activity was confirmed by 1H and 13C NMR spectroscopy, demonstrating H2 and CO2 evolution at 60 °C over 24 h. Complementary DFT calculations on a MOF-based model offer key mechanistic insights, with a modest barrier for decarboxylation consistent with experimental results. These findings highlight the promise of linker-functionalised MOFs for hydrogen generation and the challenge of identifying active species in redox-active systems.