It's a little hard to say without seeing the spaces adjacent to this area but a mirrored tile could be an option. It would give depth to the hallway.

Don't BUILD anything there. Buy a great cabinet console with storage, hang art and set up a mini bar when you entertain. It doesn't need a "built in"

I agree with Jan Moyer , also ..you can add wine racks In The kitchen .....for every day use ...and have a cabinets with ice bucket and storage ..in the hallway ..it all doesn't have to be in one place ....and may take away precious space in the hallway ....?

I do not see this as good space for a mini bar it is in a narrow hall where all the guests will be mingling I have a ton of parties every year and the best mini bar is the kitchen island since that is where everyone always ends up. If you insist on it do as Jan suggests and IMO no backsplash required .

Agreed, space seems too narrow already. Interrupts flow of energy from a Feng Shui perspective as well. Clear path is better, add art.