Does anyone have a recommendation on a compatible air purifier?
If you are just looking for one you can turn on / off, almost any non-digital purifier will work with just a “Smart Plug”. That is what I do.
I don’t have a specific recommendation, but any device that has an IFTTT channel/service can be indirectly integrated that way. The exact features exposed in the channel will vary by manufacturer, so you need to look at each one individually. I know the WeMo air purifier and the Samsung air purifier both have IFTTT channels, for example.
The WeMo channel includes a filter alert, which is kind of nice.
The Samsung Air Purifier let you set its operating mode in addition to just on/off through its channel. Those aren’t officially sold in the US, yet, though.
I’m not sure if there any other air purifiers with IFTTT channels, but it’s something to look for as you research.
The Mi Air Purifier seems to be able to be used through a separate app, but there isn’t a device handler for smartthings (yet?)
Also the Holmes air purifier @JDRoberts is reffering to has a device handler for smartthings;
That device handler is for the wemo humidifier, not air purifier.