摘要
Cu3Se2 nanocubes with tunable edge lengths of 35, 46, 52, 67, and 86 nm have been synthesized from an aqueous solution of NaOH, sodium ascorbate, copper acetate, and Na2SeSO3 and heating the solution to 50 °C for 20 min. Adjustment in volume of the added NaOH solution tunes the nanocube size. X-ray diffraction (XRD) analysis shows that the nanocubes have a tetragonal crystal structure. The optical band gap decreases continuously from 2.33 eV for the 35 nm Cu3Se2 cubes to 2.02 eV for the 86 nm cubes. All samples also absorb near-infrared (NIR) light from 700 nm to beyond 2200 nm. Interestingly, the NIR band centered at around 1150 nm is relatively unchanged despite particle size variation. Irradiation of the nanocube solutions with 808 and 1064 nm lasers increases the solution temperature by as much as 17.5 °C within 2 min, showing that the NIR absorption band is plasmonic in nature resembling that of metals. Thus, Cu3Se2 nanocubes possessing surface plasmon resonance (SPR) properties can be easily obtained without external doping.