Infrared plasma photothermal conversion of Cu2-xS/cellulose nanofilms prepared by sequential reaction

•The high density copper sulfide nanoparticles grown on cellulose films exhibit good absorption in the range of 300 to 1000 nm.•The large ratio imbalance components of Cu and S produce a large number of free carriers, which play an important role in the excellent conductivity.•The Cu2-xS/cellulose composite film exhibit excellent photothermal conversion and Ultra-high stability. Highly dense Cu2-xS/cellulose composite film is prepared by the sequential reaction method and perform perfect absorb from 300 to 1000 nm waveband and excellent conductivity owing to high concentration of charge carriers. Cu2-xS nanoparticles present typical plasma resonance effect in the near infrared region due to a large number of copper vacancies. The systematic photothermal investigation proves that the Cu2-xS/cellulose composite film has good photothermal conversion characteristics and high stability. The good photothermal conversion of Cu2-xS depends on two factors: typical semiconductor characteristics and plasma resonance characteristics in infrared band.