CHEMICAL SYNTHESIS. The photochemical synthesis of metallic oxide nanoparticles traces back to the 18th century when Xxxxxxx discovered that certain silver salts darken when exposed to light.95 Recent advances in metallic NP research have extended this classic concept of photoreaction to reveal a new application as a synthesis method for nanostructures integrated into light-emitting diodes (LEDs).96 LEDs have unique characteristics such as narrow band, low divergence angle, and high emission intensity, making them ideal as light sources to excite specific sizes and shapes of metallic NPs in photochemical reactions.97 This process has several advantages, such as the versatile and environmentally friendly method of photoinduced treatment, easy control of the in-situ generation of reducing agents, and the initiation of nanoparticle formation through photoirradiation. Recent advances in photochemistry and photo-processing techniques have provided researchers with various synthetic approaches to obtain metal nanoparticles under different conditions. The specific size and shape of the nanoparticles are determined by the synthetic conditions, making them crucial in the formulation process.98
