Carbon Dots‐Assisted Rapid Synthesis of Polypyrrole with High Uniformity for Efficient Solar‐Driven Water Evaporation

Abstract Solar‐driven water evaporation is considered one of the most promising technologies to simultaneously address the energy crisis and freshwater scarcity. Developing efficient evaporators is highly sought after. Here, a strategy to realize the rapid polymerization of pyrrole and the uniform deposition of carbon dots‐polypyrrole (CDs‐PPy) on Balsa substrate is reported by using CDs solution obtained from the exfoliation of coal pitch with HCOOH/H₂O₂ as the trigger. This unreacted HCOOH/H₂O₂ in CDs solution, which gets well reused, can act as the oxidant to oxidize pyrrole, and also play a certain role in removing unstable hemicellulose from Balsa that produces more pores on cell walls. This method also avoids the formation of large PPy aggregates and enables CDs to be incorporated into the polymeric PPy. The obtained Balsa supported CDs‐PPy (CDs‐PPy/Balsa) with high uniformity well preserves the interconnected microporous structure of Balsa. Compared to Balsa supported PPy (PPy/Balsa) synthesized via the conventional polymerization method of pyrrole using ammonium persulfate as an oxidant in HCl aqueous medium, the obtained CDs‐PPy/Balsa evaporator with high physicochemical stability and salt resistance ability shows superior solar‐driven water evaporation performance. These favorable features can lead CDs‐PPy/Balsa to a greater use in practical solar‐driven water evaporation applications.