In Situ Probing of CO₂ Reduction on Cu‐Phthalocyanine‐Derived Cu_xO Complex

Abstract An in situ measurement of a CO₂ reduction reaction (CO₂RR) in Cu‐phthalocyanine (CuPC) molecules adsorbed on an Au(111) surface is performed using electrochemical scanning tunneling microscopy. One intriguing phenomenon monitored in situ during CO₂RR is that a well‐ordered CuPC adlayer is formed into an unsuspected nanocluster via molecular restructuring. At an electrode potential of −0.7 V versus Ag/AgCl, the Au surface is covered mainly with the clusters, showing restructuring‐induced CO₂RR catalytic activity. Using a measurement of X‐ray photoelectron spectroscopy, it is revealed that the nanocluster represents a Cu complex with its formation mechanism. This work provides an in situ observation of the restructuring of the electrocatalyst to understand the surface‐reactive correlations and suggests the CO₂RR catalyst works at a relatively low potential using the CuPC‐derived Cu nanoclusters as active species.