"an air of professionalism" is correct and usable in written English. You can use it when talking about how someone is acting or appearing in a professional setting. For example: "She conducted herself with an air of professionalism during the interview.".
But an air of professionalism must be maintained.
The name seemed to evoke feelings of confidence in our customers and gave us an air of professionalism, which wasn't exactly accurate.
His newly appointed superintendent, Harry J. Corbitt, expanded the size of the executive detail and ordered additional training, efforts aimed at infusing new blood and an air of professionalism.
Besides, depending on what your bridesmaids have planned for the bachelorette party, it might be easier to maintain an air of professionalism after the party is she isn't there.
He is, it is true, every inch a GE man calm, focused and exuding an air of managerial professionalism, as you would expect from a veteran of the world's most respected company.
But they do seem to take on an extra air of professionalism that most kids their age don't have".
"They bring a real air of professionalism and great experience into our training sessions and it is beneficial for everyone.
I love the desktop app, it’s always running on my Mac. Ludwig is the best English buddy, it answers my 100 queries per day and stays cool.
Cristina Valenza
Retail Lead Linguist @ Apple Inc.