Regulating divalent metal species in aluminum-based layered double hydroxides to selectively promote photocatalytic CO production from CO2

The results indicate that Zn component can reduce the charge transfer resistance of Al-based LDHs, which leads to a higher photo-generated current density, thus achieving a high CO 2 reduction performance. • The Zn component can reduce the charge transfer resistance of Al-based LDHs. • The ZnAl-LDH presents a higher yield and selectivity of CO product than MgAl-LDH and NiAl-LDH. • The strategy of regulating divalent metal species can construct advanced LDH-based photocatalyts. Photocatalysis is a potential technology to reduce CO 2 greenhouse gases. Layered double hydroxides (LDHs) are promising photocatalysts due to good catalytic activity, low synthesis cost, and large-scale preparation. However, their CO selectivity in photocatalytic CO 2 reduction is still unsatisfactory. Herein, we have systematically studied the effects of different divalent metal species ( e.g. , Mg 2+ , Ni 2+ , and Zn 2+ ) on the CO selectivity in aluminum-based LDHs. The results indicate that ZnAl-LDH can negatively shift the conduction band to obtain a large driving power for CO 2 reduction to CO, which much improves the CO selectivity. In addition, the ZnAl-LDH also reduces the charge transfer resistance leading to a higher photo-generated current density, thus achieving a high CO 2 reduction performance. Specifically, ZnAl-LDH presents a better CO selectivity of 72.8% and a higher CO yield of 1.58 μmol·g –1 ·h –1 , than MgAl-LDH (66.2%, 0.96 μmol·g –1 ·h –1 ) and NiAl-LDH (59.8%, 1.01 μmol·g –1 ·h –1 ). This study provides a feasible strategy to improve the selectivity of CO photocatalytic reduction of CO 2 by regulating divalent metal species in aluminum-based layered double hydroxides.