Light-driven directional ion transport for enhanced osmotic energy harvesting.

Kai Xiao,Tobias Heil,Shaowen Cao,Paolo Giusto,Ruotian Chen,Fengxiang Chen,Fengtao Fan,Lu Chen,Lei Jiang

doi:10.1093/nsr/nwaa231

Abstract

Light-driven ion (proton) transport is a crucial process both for photosynthesis of green plants and solar energy harvesting of some archaea. Here, we describe use of a TiO2/C3N4 semiconductor heterojunction nanotube membrane to realize similar light-driven directional ion transport performance to that of biological systems. This heterojunction system can be fabricated by two simple deposition steps. Under unilateral illumination, the TiO2/C3N4 heterojunction nanotube membrane can generate a photocurrent of about 9 μA/cm2, corresponding to a pumping stream of ∼5500 ions per second per nanotube. By changing the position of TiO2 and C3N4, a reverse equivalent ionic current can also be realized. Directional transport of photogenerated electrons and holes results in a transmembrane potential, which is the basis of the light-driven ion transport phenomenon. As a proof of concept, we also show that this system can be used for enhanced osmotic energy generation. The artificial light-driven ion transport system proposed here offers a further step forward on the roadmap for development of ionic photoelectric conversion and integration into other applications, for example water desalination.

Highlights

Nature’s biochemical machinery is a source of inspiration for development of artificial molecular devices or ion transport systems designed to emulate the form and function of their biological counterparts
This ability raises a pertinent question for artificial light-driven ion transport systems: is there a way to drive ion transport by light in an easy and universal manner, and realize an efficient ‘ionic’ energy harvesting as in nature? we report development of an artificial light-driven ion transport system via a semiconductor heterojunction nanotube membrane that drives ion transport in a specific direction under unidirectional illumination for photocurrent generation (Fig. 1a)
We demonstrate that such semiconductor heterojunction nanotubes consisting of titanium oxide (TiO2) and polymeric carbon nitride (C3N4) enable efficient light-driven ion transport and tunable ion transport direction by controlling the heterojunction structure

Summary

Introduction

Nature’s biochemical machinery is a source of inspiration for development of artificial molecular devices or ion transport systems designed to emulate the form and function of their biological counterparts. We describe use of a TiO2/C3N4 semiconductor heterojunction nanotube membrane to realize similar light-driven directional ion transport performance to that of biological systems. We report development of an artificial light-driven ion transport system via a semiconductor heterojunction nanotube membrane that drives ion transport in a specific direction under unidirectional illumination for photocurrent generation (Fig. 1a).

Results

Conclusion