Enhancing moisture-electric power generation through in situ incorporation of carbon dots into polyelectrolyte membrane

Abstract

The electric generation performance of traditional polyelectrolyte membrane with moisture usually fall far behind expectations due to its limited hydrophilic groups and poor directional transport capacity of protons. To this end, we introduce the suspension of carbon dots (CDs) prepared by selective oxidation etching of coal pitch with the mixture of formic acid and H2O2 under ambient temperature into the aqueous solution of polyvinyl alcohol (PVA) and poly(4-styrensulfonic acid) (PSS) to fabricate a novel hybrid membrane. This membrane (1.00 cm2) continuously delivers a voltage output of 0.83 V with a short-circuit current of 5.20 μA under proper moist conditions over a prolonged period, outperforming the power generation performance of the pristine membrane and many current moisture-enabled electric generation (MEG) devices. Moreover, CDs endow the polymer membrane with more superior mechanical properties, in favor of processing and scale integration for higher power output. With excess hydrophilic groups provided by as-prepared CDs’ suspension, the denser hydrogen-bond network can be formed in the membrane and facilitates water adsorption and the formation of a higher proton concentration gradient. CDs-induced bridging interactions between PSS chains pave a fast directional transport pathway for moveable protons, resulting in a remarkable power output. Accordingly, this work offers a facile and economic method for remoulding traditional polyelectrolyte membrane to conduct highly efficient MEG for practical applications.