Interfacial Engineering of Mixed Ionic‐Electronic Conductors for Moisture‐Enabled Electric Generation

ABSTRACT Powered by the abundance and ubiquitousness of atmospheric water, moisture‐enabled electric generators (MEGs) are emerging as a promising candidate for the next‐generation power source. Here, we develop a new type of MEG that exploits the interfacial potential arising from mixed ionic‐electronic conducting metal oxides with opposite semiconducting types. The interfacial potentials of (p‐type) NiO and (n‐type) TiO 2 were increased from 0.028 V to 1.2 V by doping NiO with 14% (atomic%) ferric ions (Fe 3+ ) and TiO 2 with 0.5% (atomic%) nitride ions (N 3− ). Similarly, upon increasing the atmospheric humidity level, the output current of the Fe‐NiO/N‐TiO 2 interface was boosted from 0.052 εA to 0.277 µA, attributed to the enhanced ionic charges formed on the surface of hygroscopic Fe‐doped NiO (Fe‐NiO). Upon replacing the poorly conducting nitrogen‐doped TiO 2 (N‐TiO 2 ) with mixed conducting partially reduced graphene oxide (Pr‐GO), a 5.7 times enhancement in the current value was achieved, albeit with a 2.4‐fold reduction in output potential. The optimized mixed‐conductor‐based MEG generated sufficient power to operate small electronic devices such as a calculator and a light‐emitting diode (LED), highlighting its practical applicability for sustainable energy harvesting from atmospheric moisture.