pH-regulated thermo-driven nanofluidics for nanoconfined mass transport and energy conversion.

Bioinspired nanochannels whose functions are similar to those of the biological prototypes attract increasing attention due to their potential applications in signal transmission, mass transport, energy conversion, etc. Up to now, however, it is still a challenge to extract low-grade waste heat from the ambient environment in an aqueous solution. Herein, a thermo-driven nanofluidic system was developed to extract low-grade waste heat efficiently based on directed ionic transport at a micro-/nanoscale. A steady streaming current increases linearly with the temperature gradient, achieving as high as 14 nA at a temperature gradient of 47.5 °C (δ T = 47.5 °C) through a 0.5 cm 2 porous membrane (10 6 cm -2 ). And an unexpected theoretical power of 25.48 pW using a single nanochannel at a temperature difference of 40 °C has been achieved. This bioinspired multifunctional system broadens thermal energy recovery and will accelerate the evolution of nanoconfined mass transport for practical applications.