[seeker3 (OP)]

Atom is made from positive charged nucleus and negative charges electrons clouds.

The highest voltage in nature possible is between them.

Can we use the voltage between nucleus and electron clouds to generate electricity?

Why not?

[seeker3 (OP)]

In theory, opposite charges collide should release highest amount of energy per mass.

Release electrons into nucleus to generate energy.

The ash will be neutron dust, tiny but HEAVY.

[chiralSPO]

Unfortunately for this invention (but very good for life in general), the neutral atoms are already in their low-energy state. Neutrons spontaneously decompose, releasing electrons and protons (and energy and other particles), as do nuclei that have too many neutrons compared to protons (see: https://en.wikipedia.org/wiki/Free_neutron_decay and https://en.wikipedia.org/wiki/Beta_decay)

THERE IS NOTHING KEEPING THE ELECTRON FROM TOUCHING THE PROTON IN A HYDROGEN ATOM BECAUSE THEY ARE ALREADY "TOUCHING". (sorry for the caps--but this is a very important point).

Quantum mechanics is very non-intuitive in some ways: one of them is that the lighter a particle is, the greater its effective volume is. A proton is 1836 times heavier than an electron, and only occupies a radius just smaller than one femtometer (10^–15 meters). The electron in a hydrogen atom, is as close to "touching" the proton as one can get in the quantum world (the electron and proton have the same center of mass), but because the electron is so much lighter, it takes up more space (you can think of it as being fluffy or smeared out, whichever you prefer)--most of the electron is within 1 Å (10^–10 meters) of the center (within 1 Å of the proton).

https://www.chemistry.mcmaster.ca/esam/Chapter_3/section_2.html

[seeker3 (OP)]

What is energy? What is energy state? What is precise mechanism?

All we know for sure is electron is negative charged, proton is positive charged, they must attract each other  with the strongest force in nature. Force and motion, they must accelerate to each other and collide.

Don't matter what physics, without precise mechanism is not science, but word puzzle.

[seeker3 (OP)]

Science is not read and believe, quote here and there.

Without understood the precise mechanism, accept any theory is not correct.

Do you really understand what you quoted? If so, just say the point, why quote?

[chiralSPO]

Oh I'm sorry... I thought you were seeking truth.

The point is:

[Kryptid]

Without understood the precise mechanism, accept any theory is not correct.

You don't have to know how something works in order to know that it does, in fact, work.

[seeker3 (OP)]

When current passing through copper wire, does copper atom nucleus attract free electrons passing by?

Why free electrons don't fly into nucleus? What force/mechanism stopped electrons doing so?

[afksf1944]

Atoms can only accept certain number of electrons (clouds)

[Kryptid]

When current passing through copper wire, does copper atom nucleus attract free electrons passing by?

Yes, but not any more strongly than it attracts the electrons that were already there.

Why free electrons don't fly into nucleus? What force/mechanism stopped electrons doing so?

This has already been answered more than once: Heisenberg's uncertainty principle. Put another way, you could say that the electron has too much momentum to be confined to the nucleus.