Natural rubber

Composite number

Capacitance

Water transport

Materials science

Chromatography

Transpiration

Capillary action

Power (physics)

Biochemistry

Carbon fibers

Physical chemistry

Supercapacitor

Environmental engineering

Thermodynamics

Physics

Nanotechnology

Environmental science

Composite material

Water flow

Evaporation

Analytical Chemistry (journal)

Photosynthesis

Generator (circuit theory)

Chemistry

Electrode

Wetting

Carbon black

Optoelectronics

Electrokinetic phenomena

ACS Nano

Transpiration is the process by which water is carried in plants from the roots to the leaves where evaporation takes place. Here, we report a transpiration driven electrokinetic power generator (TEPG) that exploits capillary flow of water in an asymmetrically wetted cotton fabric coated with carbon black. Accumulation of protons induced by the electrical double layer formed at the solid (carbon black)/liquid (water) interface gives rise to potential difference between the wet and dry sides. The conductive carbon black coating channels electrical current driven by the pseudostreaming mechanism. A TEPG of 90 mm × 30 mm × 0.12 mm yields a maximum voltage of 0.53 V, maximum current of 3.91 μA, and maximum energy density of 1.14 mWh cm-3, depending on the loading of the carbon black. Multiple TEPGs generate enough power to light up a light-emitting diode (20 mA × 2.2 V) or charge a 1 F supercapacitor.

Transpiration Driven Electrokinetic Power Generator