What should be added to carbon dioxide to get ammonium carbonate CO2 + (NH4) 2CO3

What should be added to carbon dioxide to get ammonium carbonate CO2 + (NH4) 2CO3 and what will happen in the second part if it works out of course?

Given a chemical reaction C O2 +? = (NH4) 2 CO3
To obtain ammonium carbonate, ammonia with hydrogen must be added to carbon dioxide C O2, then we get the following chemical reaction.
CO2 + 2 * NH3 * H2O = (NH4) 2 CO3 + H2O;
In the second part of the expression, then hydrogen will be added.
Answer: CO2 + 2 * NH3 * H2O = (NH4) 2 CO3 + H2O;