Proton-Coupled Electron Transfer Aided Thermoelectric Energy Conversion and Storage

Low-grade heat is ubiquitous in the environment and its thermoelectric conversion by the ionic conductors remains a challenge because of the low efficiency and poor sustainability. Here we demonstrate that the thermoelectric performances can be boosted by combining the Soret effect of protons and proton-coupled electron transfer (PCET) reaction of benzoquinone and hydroquinone in hydrogels. An overall enhancement of thermopower (25.9 mV K^-1 ), power factor (5 mW m^-1  K^-2 ), figure of merit (>2.4) and continuity of power output is achieved. Moreover, an energy-storage function can be achieved by the redox couple, and a retained power output of 27.7 %, or 14 mW m^-2 for more than 3 hours is obtained by the re-balance of PCET reactants in the hydrogel after the removal of the temperature gradient.