From memory, if you use datenum to just get the time with no date, it doesn't return a number between 0 and 1. But you can get around that with mod.... So here's one option:
d = datenum(v0{1}, 'mm/dd/yyyy') + mod(datenum(v0{2}, 'HH:MM:SS'), 1);
The other way is to construct a string with both combined:
str = [v0{1}, ' ', v0{2}];
d = datenum(str, 'mm/dd/yyyy HH:MM:SS');
