Currently, more than 80 % of our world’s energy needs are met by burning fossil fuels such as natural gas. The supply of these fuels is limited and will eventually run out. Combustion of fossil fuels also generates carbon dioxide, which is a suspected accelerant of global warming and a regulatory burden for industrial emitters. One solution for reducing atmospheric CO₂ levels is carbon capture and sequestration.  Another alternative is to electrochemically reduce the emitted CO₂ into carboxylic acids, hydrocarbons or alcohols, which are useful chemical feedstock and fuels. Water can also be reduced to hydrogen gas, which can be used as a carbon-free fuel. If the energy used for these processes is generated from a renewable source such as solar or wind, we can envisage a chemical production cycle that is closed-loop with net zero carbon emission.

In this talk, we share our findings related to the electroreduction of CO₂ and water. We shall show a combined operando Raman spectroscopy and density functional theory calculation study of amorphous MoS_x films during the hydrogen evolution reaction. This investigation allowed us to directly identify sulfur atoms in MoS_x as the catalytically active sites for proton reduction. Next, the various factors that determine the selectivity of copper or CuO_x-derived copper catalysts to reduce CO₂ to ethylene, ethanol, etc. shall be discussed. Optimization of current densities at the appropriate potential windows is shown critical for designing highly selective Cu catalysts. We also share our recent work on how copper can be made almost exclusively selective for the reduction of CO₂ to formic acid, by a simple sulfur doping procedure.