Spherical shell CdS@NiO Z-scheme composites for solar-driven overall water splitting and carbon dioxide reduction. (July 2022) - Qiao, Shanshan
Abstract: Industrial applications of water splitting to produce hydrogen and carbon dioxide reduction to produce high value added products remain significant challenges, owing to the low density of electrons and holes produced by photoexcitation, rapid recombination of photogenerated carriers and sluggish redox reactions. Direct Z scheme photocatalysts have attracted much attention due to their excellent space–photogenerated electron−hole pairs and stronger redox ability. Herein, the core−shell direct Z scheme construct was established by a structure of NiO/Ni coated CdS spherical, finally achieved photocatalytic pure water splitting, simultaneously produced with stoichiometric ratio 2:1 (include 42.5 μmol g − 1 h − 1 H2 and 20.1 μmol g − 1 h − 1 O2 ), AQY (apparent quantum yield) was 1.6% (in pure water system, λ = 420 nm) and STH (Solar to Hydrogen Conversion Efficiency) was 2.1 × 10 −4 %. The yield of CO from photocatalytic reduction of carbon dioxide was 36.7 μmol g − 1 h − 1 . Insight into the reaction mechanism provides an initial attempt to reveal the direct Z scheme of NiO@CdS and the Schottky junction of NiO/Ni together to promote the photocatalytic performance. This work can provide a strategy scheme for constructing a bifunctional sphere−shell direct Z scheme catalyst and applying it to photocatalytic overall water splitting and carbon dioxide reduction. Graphical abstract: Image 1 Highlights: The direct Z scheme construct was established by NiO/Ni coated on CdS spherical. Photocatalytic water splitting performance and CO2 reduction achieved. S vacancy promotes electron capture and direct Z scheme increases redox ability. Schottky junction and direct Z scheme promote photocatalytic performance.