. H-O-H + 2 H20 + N CO carbon dioxide 4H+N Hydrogen nickel One way that has been discussed to reduce the carbon dioxide in the atmosphere is to turn it back into a fuel using direct carbon recycling. The equation for a possible reaction is shown in the image. Carbon dioxide, hydrogen and nickel undergo a chemical reaction and one of the products is methane, which can be used as a fuel. In this equation, which is the catalyst? Carbon dioxide Hydrogen Nickel