Effects of different defective linkers on the photocatalytic properties of Cu-BTC for overall water decomposition

This manuscript proposed a synthesis strategy for simultaneously constructing defect structure and mixed valence coordinated unsaturated sites (CUS) in Cu-BTC (BTC=1,3,5-trihydroxybenzene) framework. Different defective linkers with increasing pKa value were used to regulate the defect concentration and Cu1+/Cu2+ CUS content. The pKa value of defective linkers was proved to be inversely proportional to the defect concentration and Cu1+/Cu2+ CUS content. Compared with pure Cu-BTC, the defective Cu-BTC samples have obviously improved specific surface area, light absorption, bandgap, and charge carrier separation rate. All of these advantages make defective variants become an excellent bifunctional overall water splitting catalyst with O2 and H2 generation rates of 3942 μmol·g-1·h-1 and 15107 μmol·g-1·h-1, respectively. Although the defective linkers with small pKa value can create more defects, excessive defects in framework will lead to the parent structure collapse, and can also serve as recombination centers to reduce the photocatalytic activity of materials.