Si-doped ZnAl-LDH nanosheets by layer-engineering for efficient photoelectrocatalytic water splitting

A highly efficient Si-doped ZnAl-LDH (denoted as Si-ZnAl-LDH nanosheet) catalyst that is derived from largearea chemical exfoliation for photoelectrocatalytic water splitting. The formation of amorphous Si-ZnAl-LDH nanosheets through chemical exfoliation or layer engineering leads to much more accessible surfaces that originally are not accessible in highly crystalline ZnAl-LDH sheets. The incorporation of Si to highly exfoliated ZnAl-LDH nanosheets generates more oxygen vacancies, increases the number of active sites, redistributes the local charge density of the active centers and effectively suppresses the recombination of the generated electronhole pairs. Specifically, the overpotential of HER and OER for Si-ZnAl-LDH nanosheet is 108 mV and 260 mV, respectively, at current density of 10 mA cm-2 under light-assisted conditions. Total applied voltage is 1.673 V for water splitting in a full cell. This work provides a novel chemical exfoliation or layer-engineering strategy for the synthesis of scalable and cost-effective LDH nanosheets with efficient photoelectric response.