Sulfur shows totally opposite faces in environmental and energy issues. Sulfur containing gases, H2S and SO2, are dominant air pollutants, while sulfur plays as the clean energy carrier for Li-Sulfur (Li-S) batteries. Herein, through confining the gaseous comproportionation reaction in water, between H2S and SO2 that normally produces uncontrollable aggregates, we develop a completely clean approach to convert the air pollutants into water-dispersed sulfur nanoparticle (WDS). The WDS is contaminant-free, size-controllable, and more promisingly solution processable, and is thus ideal for achieving solution hybridization with other materials for various applications. As a typical example, an aqueously fabricated WDS/carbon nanotube composite delivers the theoretical capacity of sulfur at 0.5Ag−1, and a capacity of ~750 mAh g−1 even at a high current density of 5.0Ag−1. In addition to the normal use of sulfur as cathode, a new-concept WDS/carbon interlayer with a low sulfur content has been designed to inhibit the shuttling of polysulfides, greatly improving the cycling performance of the Li-S battery. The proposed approach gives a good example to turning pollutants into clean energy carriers by green chemistry.