Protons are positively charged particles. Hydrogen, destined to exist without a neutron, is synonymous with a proton when it is not in molecular form. You can burn ATP to create mechanical motion that pumps out protons. They genetically engineered the ATP synthase of a bacteria in such a way that would allow it to bind to an artificial substrate. They added a string of histidines to the shaft of the ATP synthase.
Histidine is an amino acid that can bind to metal.
The team found that nickel worked the best for binding. This change allows the ATP synthase to be placed on a surface. And if you precisely place the metal, you can precisely control where your ATP synthase ends up. The team did just that, using electron beam lithography. The group added fluorescent beads to the ATP synthase that allowed the scientists to observe the movement of the motor when ATP was added to the slides.