New catalytic technologies to convert greenhouse gas CO2 into useful products by renewable energy is becoming more important than ever due to some recent alarming events from climate change consequence. Among various products from C1 chemistry (i.e. methanol, methane, formic acid), more attention is recently paid to the hydrogenation of CO2 to higher alcohols and higher hydrocarbons (green gasoline). Development of highly effective and selective catalysts remains a great challenge. Moreover, further in-depth comprehension of the reaction mechanisms offers practical guidance to new design of catalyst systems.