A cute pun on the word catalyst. The cat is representing the catalyst, quickly guiding the bonding of the blue and yellow atoms into molecules in the beaker of solution.
Where you can buy online
Buy this design on a non-medical face mask from my RedBubble US store.
You can find the design on t-shirts in most stores, but also on other products depending on the store (e.g. hoodies, mugs, stickers, notebooks, phone cases, greeting cards, cushions, socks etc).