Upconversion boosting pollutants degradation efficiency in wide-spectrum responsive photocatalysts

Area of Science:

• Materials Science
• Photocatalysis
• Nanotechnology

Background:

• Composite photocatalysts combined with upconversion materials are gaining attention for improved solar energy utilization.
• Efficient solar energy conversion is crucial for addressing environmental pollution.
• Upconversion materials can convert lower-energy photons (like near-infrared) into higher-energy photons usable by photocatalysts.

Purpose of the Study:

• To design and develop novel heterojunction photocatalysts using CoWO₄ and NaYF₄:Yb³⁺,Er³⁺.
• To investigate the structural, morphological, and elemental properties of the synthesized composite materials.
• To evaluate the photocatalytic activity and degradation efficiency of the novel heterojunctions for pollutant removal.

Main Methods:

• Synthesis of CoWO₄@NaYF₄:Yb³⁺,Er³⁺ heterojunction photocatalysts.
• Structural characterization using techniques like X-ray diffraction (XRD) and transmission electron microscopy (TEM).
• Photocatalytic activity testing for pollutant degradation, radical species trapping experiments, and fluorescence detection.

Main Results:

• Successful formation of heterojunctions between CoWO₄ and NaYF₄:Yb³⁺,Er³⁺ was confirmed.
• The composite photocatalysts exhibited significantly enhanced pollutant degradation efficiency compared to pure CoWO₄.
• A specific composite (60CoWO₄-NaYF₄:Yb³⁺,Er³⁺) showed an 87% enhancement in photocatalytic activity.
• Photo-generated holes (h+) and hydroxyl radicals (•OH) were identified as the dominant active species.

Conclusions:

• The CoWO₄@NaYF₄:Yb³⁺,Er³⁺ heterojunction photocatalysts demonstrate superior photocatalytic performance.
• The enhanced activity is attributed to the synergistic effect of CoWO₄ and the upconversion properties of NaYF₄:Yb³⁺,Er³⁺.
• These novel heterojunctions efficiently utilize a wider solar spectrum (UV-Vis and Near-Infrared) for photocatalysis.