Precise regulation of defect concentration in MOF and its influence on photocatalytic overall water splitting

Abstract

In this work, the defective Cu-BDC with different defect concentration and Cu¹⁺/Cu²⁺ coordinatively unsaturated sites (CUS) content were designed and synthesized by introducing defective linkers with different pK_a values. The low-concentration defects in Metal–organic frameworks (MOFs) structure act as the active sites to enhance their photocatalytic activity. In contrast, the high concentration defects serve as the recombination centers of photogenerated electrons and holes to decrease the transfer efficiency of charge carriers. Cu-BDC-FBA shows an excellent bifunctional photocatalytic performance for overall water splitting due to the suitable defect concentration, which gives an oxygen production rate of 3114 μmol g⁻¹ h⁻¹ and hydrogen production rate of 16 829 μmol g⁻¹ h⁻¹, respectively. It is expected that this study can deepen the understanding of the relationship between defects and photocatalytic activity, and provide a new idea for the design and synthesis of defective MOFs photocatalysts with excellent performance.