P25@CoAl layered double hydroxide heterojunction nanocomposites for CO2 photocatalytic reduction

•Nanocomposite photocatalysts have been synthesized from titania (P25) and Co-Al layered double hydroxide (LDH) components.•Heterojunctions between the semiconductor components improves photoinduced charge carrier separation and transport.•Hierarchical P25@CoAl-LDH nanocomposites are active for aqueous CO2 photoreduction to CO without sacrificial hole acceptors.

Artificial photosynthesis driven by inorganic photocatalysts offers a promising route to renewable solar fuels, however efficient CO2 photoreduction remains a challenge. A family of hierarchical nanocomposites, comprising P25 nanoparticles encapsulated within microporous CoAl-layered double hydroxides (CoAl-LDHs) were prepared via a one-pot hydrothermal synthesis. Heterojunction formation between the visible light absorbing CoAl-LDH and UV light absorbing P25 semiconductors extends utilisation of the solar spectrum, while the solid basicity of the CoAl-LDH increases CO2 availability at photocatalytic surfaces. Matching of the semiconductor band structures and strong donor-acceptor coupling improves photoinduced charge carrier separation and transfer via the heterojunction. Hierarchical P25@CoAl-LDH nanocomposites exhibit good activity and selectivity (>90%) for aqueous CO2 photoreduction to CO, without a sacrificial hole acceptor. This represents a facile and cost-effective strategy for the design and development of LDH-based nanomaterials for efficient photocatalysis for renewable solar fuel production from particularly CO2 and water.

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