Self-Assembled Asymmetric Electrodes for High-Efficiency Thermogalvanic Cells

The thermogalvanic cell (TGC) is considered a promising thermoelectric device for directly converting low-grade waste heat into electricity due to its low-cost and scalable properties. However, the low output and conversion efficiency limit its practical application. Herein, record-high thermoelectric conversion performances are achieved in the aqueous ferri/ferrocyanide ([Fe(CN) 6 ] 3− /[Fe(CN) 6 ] 4− ) based TGC by using the electrode of cobaltous oxide nanowires array on carbon cloth fiber. Because of the temperature-dependence reaction activity between CoO with [Fe(CN) 6 ] 4− , the asymmetric electrodes of Co 2 Fe(CN) 6 and CoO nanowires array on carbon cloth fiber are constructed at the hot anode and cold cathode, respectively. These self-assembled asymmetric electrodes exhibit specific catalysis toward electrode reactions at both ends of TGC, leading to a significant reduction in electronic activation energy. It is demonstrated that the electrodes have high catalytic activity and high specific surface area, enabling the construction of a high-efficiency TGC with a Carnot-relative efficiency ( η r ) of 14.8% and a maximum output power density ( P max ) of 24.5 W m −2 . This work offers an asymmetric electrode engineering pathway for the continuous evolution of TGCs.