Solar-driven reduction of CO2 to chemical feedstocks and fuels promises not only a renewable source of energy but also a means to reduce the harmful effect of this greenhouse gas in our environment. Major advancements have been made in improving the efficiencies and product selectiveness of currently known photocatalysts (or photocathodes), nonetheless, a need for rational materials discovery has been noted by the community as a step towards economical industrial-scale CO2 reduction.
In this work, we have performed the largest photocathode search to date . Starting with 68,860 candidate materials (orders of magnitude larger than previous reports), we have identified 39 new photocatalytic materials which can be easily synthesized, are robust in the highly reducing conditions needed for CO2 reduction, can harvest visible light and present a wide range of electronic properties suited for extracting different reduction products.
These materials have been identified via a systematic search based on first-principles simulations of intrinsic properties of candidate materials, some available in public databases and several computed specifically for this work through computationally expensive simulations. We have developed a screening strategy that allows us to identify semiconductors which not only fulfill metrics for synthesizability, corrosion-resistance— under the highly reducing conditions (< −0.5 V vs RHE) needed for CO2 reduction—but also exhibit bandgaps and band-edge energies suited for efficient solar-energy conversion. This computational strategy minimizes the number of computationally expensive electronic structure simulations through a judicious screening of the information which can be queried from existing information in the Materials Project database.
The 39 identified materials include arsenides, tellurides, selenides, and oxides presenting a wide range of chemistries suited for extracting different reduction products. This work provides rational guidance to the experimental synthesis, characterization, and testing of scores of new photocathode materials and also a canvas for materials design by alloying, use of co-catalysts and design of tandem devices for an enhanced efficiency, accelerating the route towards industrial scale application of photocatalytic CO2 reduction.