The bimetallic synergistic enhancement of photothermal properties in tannic acid-grafted MoS2

We systematically investigated the optical and photothermal properties of bimetallic complexation in tannic acid-grafted MoS₂ (TA-MoS₂). The TA-MoS₂ nanosheets were synthesized via an ultrasound-assisted oil-bath method. Afterwards, transition metals (TM = Fe, Co, Ni, Cu and Zn) were introduced into TA-MoS₂. The optical absorption coefficient of TM/TA-MoS₂ increased with fewer valence electrons of the TM. Based on Fe/TA-MoS₂, the introduction of other TMs forms bimetallic Fe-TM/TA-MoS₂. The Fe–Ni/TA-MoS₂ membrane with high-transmittance exhibits the optimal photothermal properties compared with the various compositions. Importantly, its highest equilibrium temperature was 33.1 °C higher than that of the pristine TA-MoS₂, and the transmittance remains above 80 %. Based on first-principles calculations, the high optical absorption coefficient of Fe–Ni/TA-MoS₂ originates from the multi-electron impurity bands formed by Fe–Ni atoms. The design of a synergistic coordination effect between dual TMs paves a new way for developing architectural photothermal glass.