Oh
What if we fill a container with carbon dioxide, and heated up the container to the point where the bonds break, and it the inside of the container had something to catch the carbon while the oxygen is released
The
clear problem is the bit where you said
heated up the container to the point where the bonds break. Exactly how much energy do you think that would need? Where is that energy coming from? Sure, you can totally split carbon from oxygen. That's not the problem. The problem is that the various means to do so are expensive or require a lot of energy (which you'd have to get from burning fossil fuels or similar).
The point is to come up with something that's
cheap and doesn't require us to pump energy into it.
One example of a decent proposal is putting iron into the ocean. Iron is the specific bottle-neck for microbe growth in the ocean, so if you add iron then other materials, including carbon dioxide, can be utilized.
Think of it this way: Imagine you have a lot of frankfurters, but you have a limited amount of buns, and you want to make as many hotdogs as possible, and someone suggests getting more frankfurters as the solution. clearly, this won't solve the problem because it's the buns that are the bottleneck, not the frankfurters. Since you have excess frankfurters, then buying more buns is the solution, since it allows you to make extra hot-dogs
cheaply since it allows you to better utilize something you already have.
Similarly, engineering "better algae" is useless, since there just isn't enough available iron to grow more algae. Adding iron filings to seawater is thus a cheap way to increase how much algae can grow, and thus how much CO2 is absorbed. They are working on this.