Bi₂O₂CO₃/red phosphorus S-scheme heterojunction for H₂ evolution and Cr(VI) reduction

Area of Science:

• Materials Science
• Photocatalysis
• Environmental Chemistry

Background:

• Red phosphorus (RP) possesses favorable electronic properties for photocatalysis but suffers from low quantum efficiency and charge carrier recombination.
• S-scheme heterojunctions offer a promising strategy to enhance charge separation and transfer, improving photocatalytic performance.
• Developing efficient photocatalysts is crucial for addressing environmental pollution and sustainable energy production.

Purpose of the Study:

• To synthesize and characterize a novel S-scheme heterojunction composite using hydrothermally treated red phosphorus (HRP) and Bi2O2CO3.
• To optimize the composition of the Bi2O2CO3/HRP composite for enhanced photocatalytic activity.
• To investigate the underlying mechanism for the improved photocatalytic performance.

Main Methods:

• Hydrothermal treatment of red phosphorus to obtain HRP.
• Synthesis of Bi2O2CO3/HRP S-scheme heterojunction composites with varying Bi2O2CO3 content.
• Optimization of Bi2O2CO3 mass fraction to identify the most effective composite.
• Evaluation of photocatalytic activity through Cr(VI) photoreduction and photolytic hydrogen production experiments.
• Characterization of photocatalytic performance using photocurrent density measurements.

Main Results:

• The 5% Bi2O2CO3/HRP composite exhibited the highest photocatalytic activity.
• Cr(VI) photoreduction and hydrogen production rates were significantly enhanced, reaching 0.22 min⁻¹ and 157.2 μmol·h⁻¹, respectively.
• The optimized composite showed a photocurrent density of 17.3 μA/cm², substantially higher than pure Bi2O2CO3 and HRP.
• The enhanced performance is attributed to the efficient separation and transfer of photogenerated charge carriers facilitated by the S-scheme heterojunction.

Conclusions:

• The Bi2O2CO3/HRP S-scheme heterojunction effectively suppresses electron-hole recombination and enhances photocatalytic activity.
• Optimized composite materials provide a viable pathway for advanced applications in environmental remediation and renewable energy.
• This study demonstrates a successful strategy for improving the photocatalytic efficiency of red phosphorus-based materials.