Towards the automation of nanoparticle syntheses: The case study of gold nanoparticles obtained at room temperature

Automation is promising to investigate in detail the effect(s) of parameters that influence the synthesis and properties of nanomaterials. However, it remains challenging to automate even selected key-steps of most wet-chemical syntheses of nanoparticles. Here, a simple, affordable, yet modular, automated station reported for the synthesis of chemicals is adapted to study nanomaterial syntheses, to timely screen larger multi-parameter spaces, to gain a deeper knowledge and awareness on parameters to control, to ultimately achieve more reproducible and sustainable syntheses. As a case study, this automated station is implemented to investigate and develop surfactant-free gold nanoparticles obtained at room temperature in alkaline water-alcohol mixtures. It is shown that the NaOH/Au molar ratio is a to-be-preferred descriptor to control the optical properties and size of the gold colloids for surfactant-free glycerol-mediated syntheses. Size control is simply achieved by carefully tuning the glycerol content and/or amount of base. For ethanol-mediated synthesis, the NaOH/Au molar ratio is also a suitable knob to control the nanoparticle properties. The results pave the way to higher throughput nanoparticle syntheses, ultimately relevant to timely build the missing larger datasets relevant for artificial intelligence, to one day routinely achieve the self-driven discovery of new nanomaterials and their related synthesis.