You cannot accomplish that with formatting alone. The Excel time 14:00 or 2:00 PM is represented internally by a fraction of a day. The number 1400 would be interpreted as DATE(1903,10,31).

You could create an event macro that is invoked each time you enter a value; and there, you can convert the data entry.

Or you could enter the following formula into a parallel column: =--TEXT(A1,"00\:00"). The double negate converts the text into numeric, interpreting 14:00 as time.

In either case, format the cell as Time or Custom hh:mm .