Direct Z-scheme 0D/2D heterojunction of CuO quantum Dots/ultrathin CoAl-LDH for boosting charge separation and photocatalytic CO2 reduction

Abstract

A direct Z-scheme 0D/2D heterojunction of CuO Quantum dots/ultrathin CoAl-LDH (CuO/CoAl-u) was fabricated by a simple electrostatic self-assembly process for photocatalytic CO2 reduction. An intimate interaction is formed between CuO and CoAl-u, which enables an effective Z-scheme interfacial charge transfer and thus boosts the charge separation as evidenced by various characterization technologies. Notably, the 4.5 %CuO/CoAl-u heterojunction achieves superior photocatalytic performance with a CH3OH yield of 283.26 μmol·g−1·h−1, which is higher than the pristine CoAl-u. Such the enhanced photocatalytic performance turns out to originate from prominent optical absorption property, effective separation of photo-induced carriers in CuO/CoAl-u and preserved higher reduction ability of CoAl-u. XPS measurements together with density functional theory calculations provide a clear description of the charge separation pathways and thus a possible mechanism for photocatalytic CO2 reduction is proposed. This work would provide a novel opportunity for the development of LDH-based photocatalysts with the enhanced activities in solar energy conversion.