Can I make liquid carbon dioxide at home.?

Sure you can , you can disolve the co2 in water which to a degree makes it liquid although not pure but easily seperable buy making home brew or alcohol by fermentation.

It will dissolve more co2 into it the greater the pressure, it comes out as a gas by lowering the pressure by venting it . to another chamber.

You can always buy carbonated spring water if not partial to craclin rose'.

The lower the temperature the easier to compress, i couldn't say what the pressures and temps may be to purify it to liquid form but the cooler the more pressure the more the same size tank will hold. check your check valves.

Ob1

Hydrogen would not be all that dangerous store. I have never seen a practical device for fusing hydrogen and carbon into a liquid hydrocarbon, mostly I believe, due to a fairly high enthalpy of the conversion and a rather complex process, first you need to extract carbon from from source. Then fuse it with hydrogen to produce a liquid such as propane that has an enthalpy of around 80 J/g. That is why it has been proposed to dispense hydrogen directly at the pump and not develop, what is probably a fairly elaborate process and sacrifice additional energy, to convert carbon and hydrogen into a liquid. There have been practical processes developed to liquify coal by combining it directly with water. These have had limited success, as the resulting fuel can be very aggressive on the interior of internal combustion engines.

How To Make Liquid Co2

No. CO2 doesn't come in a liquid. If it did, I'm sure Pepsi would find a way to bottle it.

No, not unless you have lots of money to spend.