Enhancing the CO(2) Electroreduction of Fe/Ni‐Pentlandite Catalysts by S/Se Exchange

The electrochemical reduction of CO(2) is an attractive strategy towards the mitigation of environmental pollution and production of bulk chemicals as well as fuels by renewables. The bimetallic sulfide Fe(4.5)Ni(4.5)S(8) (pentlandite) was recently reported as a cheap and robust catalyst for electrochemical water splitting, as well as for CO(2) reduction with a solvent‐dependent product selectivity. Inspired by numerous reports on monometallic sulfoselenides and selenides revealing higher catalytic activity for the CO(2) reduction reaction (CO(2)RR) than their sulfide counterparts, the authors investigated the influence of stepwise S/Se exchange in seleno‐pentlandites Fe(4.5)Ni(4.5)S(8‐Y)Se(Y) (Y=1–5) and their ability to act as CO(2) reducing catalysts. It is demonstrated that the incorporation of higher equivalents of selenium favors the CO(2)RR with Fe(4.5)Ni(4.5)S(4)Se(4) revealing the highest activity for CO formation. Under galvanostatic conditions in acetonitrile, Fe(4.5)Ni(4.5)S(4)Se(4) generates CO with a Faradaic Efficiency close to 100 % at applied current densities of −50 mA cm(−2) and −100 mA cm(−2). This work offers insight into the tunability of the pentlandite based electrocatalysts for the CO(2) reduction reaction.