Urchin-like hierarchical CoZnAl-LDH/RGO/g-C3N4 hybrid as a Z-scheme photocatalyst for efficient and selective CO2 reduction

A unique urchin-like CoZnAl-LDH/RGO/g-C3N4 (LDH/RGO/CN) Z-scheme photocatalyst, which is fabricated by the hydrothermal synthesis of CoZnAl-LDH and the in situ loading of RGO and g-C3N4, is developed for the photocatalytic conversion of CO2. The special spiny external surface and hollow inner cavity endow LDH/RGO/CN with a significantly enhanced light-harvesting capacity. The well-distributed g-C3N4 nanosheets on the CoZnAl-LDH nanoplates, combined with RGO as an electron mediator, constructs an excellent heterosystem with numerous interfaces, efficient charge separation and highly exposed catalytic active sites. The Z-scheme charge-transfer process promotes the oxidizability and reducibility of CoZnAl-LDH and g-C3N4. Furthermore, the synergistic effect among the components contributes to intense adsorption and chemical activation towards CO2, which reduces the reaction barrier for CO2 photoreduction. As a result, the optimized LDH/RGO/CN exhibits highly efficient and selective photocatalytic CO2 conversion to CO. The special 3D urchin-like architecture paves a new way for design of photocatalyst with ideal performance.