Preparation of Highly Stable Black Phosphorus by Gold Decoration for High‐Performance Thermoelectric Generators

Abstract For thermoelectric (TE) applications, the surface of exfoliated black phosphorus (BP) can be successfully functionalized with Au nanoparticles (NPs), leading to significantly enhanced TE performance for a controlled Au NP content. A facile and selective decoration of metal species on the defect sites of BP is achieved by the spontaneous formation of Au NPs on the surface of BP through a redox reaction of Au precursors. Such a heterostructure provided by the Au decoration of BP enhances electrical conductivity (from 0.001 to 63.3 S cm −1 ) through tuning of the charge carrier concentration and retains the initial Seebeck coefficient of BP. Consequently, the TE power factor of the Au‐decorated BP increases significantly to 68.5 µV m −1 K −2 , which is 2740 times that of the pristine BP. More significantly, in contrast to the severe degradation of the pristine BP in the air, surface‐functionalized BP exhibits excellent stability upon exposure to air for a long period, which is beneficial for practical TE applications. Given these interesting and unique properties of Au‐decorated BP, a vertical TE generator with a high power output of 79.3 nW (Δ T = 2 °C) is prepared by using the Au‐decorated BP as a p‐type TE material.