Distinctive synthesis of CdS-based photocatalysts based on a Prussian blue analog induction strategy for efficient solar-driven water splitting applications

Abstract

Prussian blue analogs (PBAs) are the oldest artificial cyanide-based coordination polymers similar to metal–organic frameworks (MOFs) in structure, composition, and physicochemical properties. In this work, a PBA induction strategy was applied to develop Cd-based frameworks and further synthesize CdS-based photocatalytic nanomaterials for improving solar-to-H₂ conversion. First, the PBA induction strategy was used to synthesize Cd-based frameworks including Cd-PBA, MnCd-PBA and ZnCd-PBA. Then, they are converted into CdS-based photocatalysts with enhanced photocatalytic hydrogen evolution performance. All the resulting Cd-/CdS-based frameworks show a cube-like structure and morphology. In comparison with previously reported CdS-based nanoparticles, the cube-like CdS-based photocatalysts exhibit some advantageous features for photocatalytic hydrogen evolution reactions with enlarged surface area, promoted visible-light-absorption capability, decreased band-gap energies, and increased reduction reaction driving forces. In addition, the resulting ZnCdS frameworks exhibit more improved photocatalytic hydrogen evolution performance than CdS and MnCdS, and the hydrogen evolution rate is up to 5.5 mmol g⁻¹ h⁻¹ using a 5 W LED light with a light-power of about 13.1 mW cm⁻² and 21 mmol g⁻¹ h⁻¹ using a 300 W xenon lamp with a light-power of about 510 mW cm⁻². Besides, it achieves a solar-to-H₂ (STH) conversion efficiency of 0.17% and apparent quantum efficiency (AQE) of 1.08% at 400 nm in a cocatalyst-free system.