Plasmonic Carbon Nitride Polymers to Boost Hydrogen Generation

Abstract Plasmonic organic polymers with strong surface plasmon resonance (SPR) hold exciting prospects in various fields but are challenging to synthesize. Herein, SPR is successfully constructed on carbon nitride polymers by photoelectron accumulation for enhanced photocatalysis. NCN‐modification on carbon nitride causes the separated highest occupied molecular orbit/lowest unoccupied molecular orbit distribution in its electronic structure for efficient charge separation. Long‐lived photoelectron accumulation on NCN‐modified carbon nitride polymer (NCN‐CN x ) is observed by single‐particle photoluminescence spectroscopy, causing strong SPR absorption in the 500–800 nm spectral region. Electron‐density‐dependent SPR of NCN‐CN x is highly sensitive to oxygen, making it a plasmonic sensor for oxygen detection. The positive roles of SPR in greatly promoting photoreactions over NCN‐CN x are demonstrated by NH 3 BH 3 decomposition, and 13 mL h −1 hydrogen is generated under > 500 nm light irradiation, five‐fold higher than that of non‐plasmonic H 2 N‐CN x . Moreover, SPR of NCN‐CN x can greatly promote photocatalytic hydrogen generation to be 1.1 mmol g −1 (3 h) under > 500 nm irradiation and the synergy between intrinsic bands and SPR excitation boosts 3.1 mmol g −1 (3 h) hydrogen generation under > 400 nm irradiation. This work provides clear evidence that SPR engineering on organic polymer can boost light harvesting for efficient photocatalysis.