Neutralization Reaction Assisted Chemical-Potential-Driven Ion Transport through Layered Titanium Carbides Membrane for Energy Harvesting.

Chemical potential energy harvesting from the concentration gradient has been largely improved recently due to the development of nanofluidic energy conversion systems. However, the reported systems mainly focus on improving the membrane's performance but neglect the forms of concentration gradient. Here, we demonstrate the chemical reaction assisted chemical-potential-driven directional ion transport through layered titanium carbides membranes for energy harvesting. The MXene membrane with negatively charged nanochannels shows excellent cation selectivity and could reach 1.1 W/m for a 500-fold salinity gradient. By adopting the traditional neutralization reaction, HCl/KOH as the acid-base pair (ABP), the power density can reach 7.89 W/m with 1 M ABP due to the maintained transmembrane proton gradient. Besides, the membrane's excellent acid-base stability renders the power density stable for ∼192 h without obvious damping. This work provides new inspiration for industrial waste treatment issues and would be worth exploring its potential applications in extreme environments.