Function-switchable metal/semiconductor junction enables efficient photocatalytic overall water splitting with...

Area of Science:

• Materials Science
• Photocatalysis
• Renewable Energy

Background:

• Titanium dioxide (TiO2) is a widely studied photocatalyst but often limited by its UV light absorption.
• Achieving efficient photocatalytic overall water splitting (POWS) and controlling oxidation products remain significant challenges.
• Metal/semiconductor heterojunctions offer potential for enhanced photocatalytic activity and selectivity.

Purpose of the Study:

• To design and synthesize a novel Cu/TiO2 hollow sphere photocatalyst for efficient POWS.
• To investigate the photocatalytic performance under both UV and visible light.
• To explore the wavelength-dependent control over water oxidation products (H2O2 or O2).

Main Methods:

• Synthesis of TiO2 hollow spheres.
• Modification with copper nanoparticles (Cu NPs) to form Cu/TiO2 heterojunctions.
• Evaluation of photocatalytic overall water splitting (POWS) performance under UV and visible light irradiation.
• Analysis of reaction pathways and product selectivity using different wavelengths.

Main Results:

• The Cu/TiO2 photocatalyst demonstrated excellent POWS performance, particularly under visible light, surpassing existing TiO2-based materials.
• A metal/semiconductor junction (Schottky interface) was successfully formed between Cu and TiO2.
• Wavelength-dependent selectivity was achieved: UV light favored H2 and H2O2 production, while visible light promoted H2 and O2 production.
• Under UV light, TiO2 electrons were captured by Cu NPs, and photoholes produced H2O2.
• Under visible light, Cu NPs acted as plasmons, injecting hot electrons into TiO2 for H2 production, and hot holes on Cu NPs produced O2.

Conclusions:

• The developed Cu/TiO2 hollow spheres represent a highly efficient photocatalyst for POWS under both UV and visible light.
• The rational design of the metal/semiconductor junction allows for tunable selectivity of water oxidation products (H2O2 or O2) by controlling irradiation wavelengths.
• This work provides insights into the mechanisms of function-switchable photocatalysis and offers a promising strategy for targeted hydrogen and oxygen production.