If the cats the dominant 'alpha' for the area then they will often leave their poo uncovered, as a warning to other cats. You need to break the habit of the cat using your footpath, so this sometimes works :-
Clean your path with a strong solution of Jeyes fluid. Then get some mothballs and crush them and scatter them all along the path. Don't crush the mothballs too much or the wind might blow them away. Keep renewing the mothballs for about a week or longer.
DO NOT use Jeyes fluid anywhere cats will walk as it is very very poisonous to them.... use chlorine bleach instead its safer.
Scatter some prickly holly or hawthorn cuttings over the area....it will act as a deterrent (would you use a loo seat made of holly? to a cat its the same thing) and cats hate citrus so lemon/orange peel amongst the prickly stuff helps too (lemon is poisnous to felines too but the will leave peel alone)
No human urine would not work as it would not be recognised as feline and therefore not a threat..... a nice spray of lion or tiger wee would work though just imagine big butch tomcat wandering across to do a bit of scent marking wandering away looking worried.....thinking don't think I'll bother....didn't like that patch anyway....
Have tried those electronic things and don't seem to work.
Older cats frequently foul without digging, even on top of ground azaleas etc. The only effective way is to see if you can buy one of these movement sensor activated gardenhose gadgets.
Mind that it makes no distinction between cats and humans so when it is on don't have it pointing toward where any visitor might come in.... actually....... no, I am not going there.