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 large-area 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 electron-hole 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.