Construction of novel intramolecular g-C3N4 based D-A1-π-A2 conjugated copolymers with promoted charge separation for efficient photocatalytic hydrogen evolution

In the strategies of modifying g-C 3 N 4 by changing its electron transport structure, it has been demonstrated that constructing donor-acceptor (D-A) or D-π-A g–C 3 N 4 –based conjugated copolymers can obviously accelerate the separation of charge carriers. Inspired by their advantages, a novel g–C 3 N 4 –based D-A 1 -π-A 2 type polymer was designed and synthesized via the thermal copolymerization of urea and PA-PM (the product of the amidation reaction between PA and PM). As a result, the prepared CN-PA-PM photocatalysts with D-A 1 -π-A 2 structure not only improve visible-light response, but also promote the separation of charge carriers, thereby achieving superior photocatalytic hydrogen evolution activity. The optimized CN-PA-PM-13 polymer has the best hydrogen evolution efficiency of 17.79 mmol g −1  h −1 under visible light (λ > 420 nm), which is 33.7 times that of pure g-C 3 N 4 . This work presents a new design concept for g–C 3 N 4 –based polymer photocatalysts with high optical absorption capability and effective carrier separation ability.