Delaminated CoAl‐Layered Double Hydroxide@TiO 2 Heterojunction Nanocomposites for Photocatalytic Reduction of CO 2

Photocatalytic reduction offers an attractive route for CO 2 utilization as a chemical feedstock for solar fuels production but remains challenging due to the poor efficiency, instability, and/or toxicity of current catalyst systems. Delaminated CoAl‐layered double hydroxide nanosheets (LDH‐DS) combined with TiO 2 nanotubes (NTs) or nanoparticles (NPs) are promising nanocomposite photocatalysts for CO 2 reduction. Heterojunction formation between visible light absorbing delaminated CoAl nanosheets and UV light absorbing TiO 2 nanotubes greatly enhances interfacial contact between both high aspect ratio components relative to their bulk counterparts. The resulting synergic interaction confers a significant improvement in photoinduced charge carrier separation, and concomitant aqueous phase CO 2 photocatalytic reduction, in the absence of a sacrificial hole acceptor. CO productivity for a 3 wt% LDH‐DS@TiO 2 ‐NT nanocomposite of 4.57 µmol g cat ‐1 h ‐1 exhibits a tenfold and fivefold increase over that obtained for individual TiO 2 NT and delaminated CoAl‐LDH components respectively and is double that obtained for 3 wt% bulk‐LDH@TiO 2 ‐NT and 3 wt% LDH‐DS@TiO 2 ‐NP catalysts. Synthesis of delaminated LDH and metal oxide nanocomposites represents a cost‐effective strategy for aqueous phase CO 2 reduction.