Polyacid doping-enabled efficient solar evaporation of polypyrrole hydrogel

Abstract

Solar evaporation opens opportunities for solving the problem of global water scarcity. Polypyrrole (PPY) hydrogels are promising materials for solar steam generation, however, the improvement of steam generation ability remains a challenge. In this paper, we developed a “polyacid doping” strategy by introducing butane tetracarboxylic acid (BTA) to synthesize a novel BTA-doped PPY hydrogel referred to as PPY/BTA hydrogel, that is cross-linked by PPY ligaments with diameters of ~200 nm. Due to the successful doping with hydrophilic BTA, PPY/BTA hydrogel exhibits an enhanced solar energy conversion efficiency (ƞ = 89%) under simulated sunlight (1 kW m−2). Additionally, the evaporation rate (V) of water can reach 1.90 kg m−2 h−1 which is 1.55 times higher than the value (1.22 kg m−2 h−1) obtained using a common PPY product without BTA. This is the most prominent among the reported PPY hydrogels under 1 sun irradiation. Moreover, efficient solar evaporation is found in regenerating wastewater containing Ag nanoparticles and dye, as well as seawater desalination, displaying wide applications. The synthesis method represents a rational design of a high-performance PPY hydrogel for solar evaporation, and could also shed light on fabricating conducting polymer networks for other applications.