The effective role of open metal sites in defective quasi-MOF-801 as hydrogen generation reactions catalyst

Abstract

Converting metal-organic frameworks (MOFs) to quasi-MOFs is a thermally controlled manner for removing the ligands, generating structural defects, and increasing porosity. In the hydrolysis of NaBH₄, unsaturated metal centers serve as catalysts to release hydrogen. The Response Surface Methodology (RSM) technique determined the optimal catalytic reaction conditions. The quasi-MOF-801 framework produced at 280 °C (Q801-280) demonstrates the highest turnover frequency in the series, measuring 10500 ml min⁻¹ g⁻¹ at room temperature in the absence of a base. It has an activation energy of 55.98 kJ mol⁻¹. The exceptional catalytic performance of Q801-280 can be attributed to its unique structure, which includes micropores, mesopores, and unsaturated Lewis acid sites. It supports the Langmuir-Hinshelwood model, indicating that both reactants are adsorbed on the catalyst surface. The catalyst dosage and BH₄⁻ concentration also significantly influence the reaction.