pd combine date time

If df.Date and df.Time are of type str:
pd.to_datetime(df.Date + ' ' + df.Time)

If df.Date and df.Time are of type datetime.date and datetime.time respectively:
pd.to_datetime(df.Date.astype(str) + ' ' + df.Time.astype(str))

Here is what the above code is Doing:
1. Convert df.Date to a string using the astype() method.
2. Convert df.Time to a string using the astype() method.
3. Concatenate the new strings together using the string concatenation operator (+).
4. Pass the concatenated string into pd.to_datetime().