CO2-crosslinked cellulose for radiative-cooling-driven passive thermoelectric devices: one stone, two birds†

Abstract

Radiative-cooling-driven passive thermoelectric devices (RC-TEDs) offer a potentially sustainable energy solution. However, most RC-TED strategies utilize unsustainable polymers. Herein, a green and sustainable CO₂-crosslinked cellulose (Pulp-CO₂) was developed for simultaneous use as a passive radiative cooling membrane and an ionogel thermoelectric scaffold. The incorporation of CO₂ in the form of carbonate group linkages in the cellulose backbone resulted in a superior passive radiative cooling effect of the membrane and improved the thermoelectric efficiency of the ionogel compared to the pure pulp. The integrated RC-TED, comprising the Pulp-CO₂ membranes and ionogels, exhibited an impressive thermal voltage output of 1200 mV with a subambient temperature reduction of 5.0 °C under simulated solar radiation (280 W m⁻²), highlighting its potential in low-grade energy harvesting. Thus, this all-cellulose inspired RC-TED device showcases a promising and sustainable strategy for converting solar energy into electricity cost-effectively.