  In the field of machine learning (ML) for materials optimization, active
learning algorithms, such as Bayesian Optimization (BO), have been leveraged
for guiding autonomous and high-throughput experimentation systems. However,
very few studies have evaluated the efficiency of BO as a general optimization
algorithm across a broad range of experimental materials science domains. In
this work, we evaluate the performance of BO algorithms with a collection of
surrogate model and acquisition function pairs across five diverse experimental
materials systems, namely carbon nanotube polymer blends, silver nanoparticles,
lead-halide perovskites, as well as additively manufactured polymer structures
and shapes. By defining acceleration and enhancement metrics for general
materials optimization objectives, we find that for surrogate model selection,
Gaussian Process (GP) with anisotropic kernels (automatic relevance detection,
ARD) and Random Forests (RF) have comparable performance and both outperform
the commonly used GP without ARD. We discuss the implicit distributional
assumptions of RF and GP, and the benefits of using GP with anisotropic kernels
in detail. We provide practical insights for experimentalists on surrogate
model selection of BO during materials optimization campaigns.
