No Purple Hearts were not awarding during WWI, soldiers received a red "wound stripe" that they would wear on their uniforms. However soldiers were able to retroactively request a purple heart, is they could show evidence they were wounded during the war.
Someone from the National Archives can provide updated information but in the past we've sent people to the Awards and Decorations branch. You do have to have some official military document which shows proof the soldier was wounded in service.
Texas Military Forces Museum
Dear Ms. Balch,
Thank you for posting your request on History Hub!
The Purple Heart medal as it is known today was not awarded during WWI. It was established in 1932, but was and can be awarded retroactively to soldiers who served after April 5, 1917. Please read more about the history of the Purple Heart in this article, “A Heart of Purple” from NARA’s Prologue (Winter 2012 issue) magazine.
We hope this is helpful. Best of luck with your research!