What are the current top notch research areas of Chemical Engineering?

An easily observable proof of this is to simply look at department names pre 2000 and post 2000. Only a handful of departments (in USA) still hold the name Chemical Engineering. Nearly all departments have changed names to the effect of Chemical and Biological Engineering, Chemical and Bio-molecular Engineering, Chemical Engineering and Nanoscience etc. The biggest science players in ChemE are biological sciences.

Biotechnology, and the subsea sector seem to be a key area over the last few years

I apologize for the answer, I leave the answer to experts specialists in this field that's not my specialty field