Flexible nanosheets for plasmonic photocatalysis: microwave-assisted organic synthesis of Ni–NiO@Ni2CO3(OH)2 core–shell@sheet hybrid nanostructures

Abstract

Visible light-active nickel-based plasmonic photocatalysts provide a cost-effective alternative to noble metals. However, their rarity, fragility, and limited understanding pose challenges. This work presents a microwave-assisted organic synthesis of a Ni–NiO@Ni₂CO₃(OH)₂ core–shell@sheet plasmonic photocatalyst. By employing time and power dependent synthesis, this catalyst exhibits flexible Ni₂CO₃(OH)₂ nanosheets enveloping the Ni–NiO structure, surpassing the pristine Ni@NiO/NiCO₃ core–shell counterpart. Chemical reaction mechanisms suggest that irradiation of pristine Ni–NiO/NiCO₃ nano structures leads to breakage of amorphous NiCO₃ to Ni²⁺ and CO₃²⁻, which further, in the presence of water solvent, interacts with OH⁻ ions leading to the formation of Ni(CO₃)·Ni(OH)₂. With enhanced light absorption and photocatalytic properties, the resulting core–shell@sheet photocatalyst demonstrates double the hydrogen evolution reaction yield (40 μmol g⁻¹ h⁻¹) compared to the pristine catalyst (20 μmol g⁻¹ h⁻¹). The enhanced H₂ yield is attributed to the flexible sheets, cross-dimensional photocatalyst structure, increased surface area for surface reactions, and higher H₂ activity of Ni₂CO₃(OH)₂. This research showcases the potential of microwave-assisted synthesis in developing flexible nanosheets with superior solar water splitting performance.