Since hydrogen is more buoyant than helium, I wonder if it could be mixed with something which reduces the flame? Either in the gas or in the outer layer of a t

Since hydrogen is more buoyant than helium, I wonder if it could be mixed with something which reduces the flame? Either in the gas or in the outer layer of a two layer balloon. It just seems like if a substitute for party balloons is needed then exploring alternate gas mixtures might be low-hanging fruit compared to engineering lightweight yet low-cost vacuum structures.