Self‐Assembled Asymmetric Electrodes for High‐Efficiency Thermogalvanic Cells

Abstract 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.