A Nanojunction Polymer Photoelectrode for Efficient Charge Transport and Separation

Area of Science:

• Materials Science
• Electrochemistry
• Photocatalysis

Background:

• Carbon nitride (CN) based materials are promising for photoanodes but suffer from charge recombination and slow charge transfer.
• Existing CN films exhibit intrinsic drawbacks limiting their efficiency in photoelectrochemical applications.

Purpose of the Study:

• To develop a metal-free photoanode with enhanced performance by addressing limitations of bulk carbon nitride.
• To fabricate a novel nanojunction architecture for improved charge dynamics and photocurrent generation.

Main Methods:

• A one-step synthesis approach was used to create a B-doped carbon nitride nanolayer on bulk carbon nitride (s-BCN).
• Characterization involved photocurrent measurements, incident photon-to-current efficiency (IPCE), electrochemical impedance spectroscopy, Mott-Schottky plots, and intensity-modulated photocurrent spectroscopy.

Main Results:

• The s-BCN photoanode achieved a photocurrent density of 103.2 μA cm⁻² at 1.23 V vs. RHE, a 10-fold increase over bulk graphitic carbon nitride (G-CN).
• An exceptionally high IPCE of ca. 10% at 400 nm was recorded.
• The nanojunction architecture led to mitigated deep trap states, a >10x faster charge transfer rate, and ~3x higher conductivity.

Conclusions:

• The developed B-doped carbon nitride nanojunction photoanode effectively overcomes intrinsic limitations of CN materials.
• This architecture demonstrates superior charge separation and transfer, leading to significantly enhanced photoanode performance.
• The findings present a promising strategy for designing efficient metal-free photoanodes for energy conversion applications.