Highly efficient binary copper−iron catalyst for photoelectrochemical carbon dioxide reduction toward methane

Significance The production of solar fuels from CO 2 using sunlight and electricity provides one promising route for reducing atmospheric carbon emissions and storing intermittent solar energy. The rational design of an efficient and inexpensive electrocatalyst is the key. We developed a binary copper−iron catalyst for photoelectrochemical CO 2 reduction toward methane. The theoretical calculations suggest that Cu and Fe in the binary system can work in synergy to spontaneously favor CO 2 activation and conversion for methane synthesis. The earth-abundant CuFe catalyst exhibits a high current density with an impressive methane Faradaic efficiency using industry-ready planar silicon photoelectrodes under one-sun illumination. This work presents a unique, highly efficient, and inexpensive route for solar fuels synthesis.