Optimizing the piezocatalytic hydrogen production activity of metal-organic frameworks through precise defect engineering

Abstract

The piezocatalytic efficiency of metal–organic frameworks (MOFs) is often limited by their weak piezoresponse. Herein, using UiO-66 as a model system, we demonstrate that defect engineering can effectively enhance both the piezoelectric and piezocatalytic performance of MOFs. Piezoresponse force microscopy reveals that the piezoelectric coefficient of defect-engineered UiO-66 increases up to 6.25 times compared with the pristine crystal. Molecular dynamics simulations attribute this enhancement to additional polarization generated by the flexoelectric effect near defects. Piezocatalytic hydrogen evolution experiments, supported by electrochemical analyses and density functional theory calculations, confirm that the improved catalytic activity arises from the synergistic effects of defect-induced charge separation, enhanced carrier transport, and a reduced energy barrier for hydrogen adsorption. The optimized defective UiO-66 achieves nearly twice the hydrogen production rate of its pristine counterpart under identical conditions. This study provides mechanistic insight into the role of defects in modulating piezoelectricity and catalytic performance, and highlights defect engineering as an effective strategy to boost the piezocatalytic hydrogen evolution activity of MOFs.