Methylated precursor leads to carbon nitride (CNx) with improved interfacial interactions for enhanced photocatalytic performance

The utilization of carbon nitride (CNx) as a benchmark organic photocatalyst for various solar energy conversion reactions has gained traction amongst the catalysis community in recent times. This has been occasioned by the facile synthesis of CNx coupled with its visible light photocatalytic performance and good stability. However, a persistent limitation of the application of CNx in solution-based photocatalytic reactions is poor interfacial interactions with substrate or sacrificial agents as a result of poor dispersibility. Using a copolymerization approach, we synthesize CNx materials with hydrophilic surface groups by calcining a mixture of melamine and methylated melamine salts (Mel(meth)) at 550 degrees C for 4 hours. The resulting modified CNx materials are water-dispersible and show red shifts in their absorption onsets and photoluminescence (PL) maxima. Compared with benchmark CNx, the modified CNx materials show broadening in their XRD peaks, suggesting more disordered and amorphous materials. We demonstrate some distinctions in the charge carrier dynamics between the modified CNx materials and the benchmark CNx by acquiring and analyzing their transient absorption spectroscopy (TAS) data. We investigate the photoactivity of the synthesized materials towards hydrogen evolution reaction (HER) and Rhodamine B dye degradation using a visible 405 nm LED light source. The apparent quantum yield (AQY) and dye degradation efficiency are improved for all modified samples compared to benchmark CNx. We attribute the promising photoactivity of the modified samples to better interfacial interactions with other species within the aqueous environment. Overall, we believe this work may shed light on a general strategy for designing organic polymer photocatalysts with desired surface properties for targeted applications.