Aqueous photo-induced high shear shape selective pristine silver nano/micro particles†

We report an efficient photo-contact electrification (CE) method for controlling the synthesis of pristine silver nanoparticles of different shapes, as one, two, and three-dimensional materials, notably rods, spicules and triangles. This uses a vortex fluidic device (VFD) which houses a rapidly rotating quartz tube tilted at 45° while the aqueous silver nitrate thin film is irradiated at 254 nm. The photo-CE associated with the mechanical energy imparted into the liquid in the microfluidic platform allows control of the size and shape of the nanoparticles, and some micron size particles, depending on the rotational speed of the tube and concentration of silver nitrate. Uniform shapes are generated with pristine surfaces in the absence of added reducing agents, with processing scalability under continuous flow. This synthetic method is also simple and cost-effective, and overall adheres to the principles of green chemistry.