The invention belongs to the technical field of nano material preparation, and discloses a method for green synthesis of nano spherical silver
powder from black bean and natto extracts, which comprises the following steps: adding a
sodium borohydride solution into a first
silver nitrate solution, and magnetically stirring to obtain a yellow
seed crystal solution; a dispersing agent is added into the second
silver nitrate solution, then the pH is adjusted to 3.8-4.2, and a
mixed solution A is obtained; adding the
mixed solution A into the black bean and natto extract solution, and uniformly mixing to obtain a growth solution; adding the
seed crystal solution into the growth solution, and stirring to obtain a
mixed solution B; adding a catalyst into the mixed solution B, and carrying out
electric field induction,
solid-liquid separation and washing to obtain a washing product; and polyhydric
alcohol is added into the washing product, then treatment is conducted through magnetic stirring, after magnetic stirring is completed,
solid-liquid separation is conducted, a
solid product obtained through separation is subjected to
vacuum drying, and the nanometer spherical silver
powder is obtained. The nanometer spherical silver
powder prepared through the method is controllable in particle size, narrow in distribution, high in
sphericity degree and high in purity.