A selectivity switch for CO2 electroreduction by continuously tuned semi-coherent interface

The bigger pictureAlthough Cu possesses suitable binding energies toward carbon-based intermediates, it shows limited product selectivity due to the unpredictable multi-electron transfer and reaction barriers, leading to the simultaneous formation of more than 10 different products. Herein, by implementing an energy-related affinity synthesis strategy, we realized efficient tuning of the semi-coherent interfaces, leading to continuously changed chemical states of Cu sites. Hence, we can manipulate the decisive factors toward product selectivity, including coverage of intermediate, adsorption configuration, and adsorption energy. The dimer, Janus, and acorn-like Janus Au–Cu catalyst can produce CH3OH, C2H4, and C2H5OH, respectively. Moreover, the synthesis is reproducible and scalable, holding the potential for industrialization. This work enriches the design principle of the intermediate-selectivity relationship for tandem catalysts.Highlights•Au–Cu Janus nanocrystals with continuously tuned interfaces•Semi-coherent interface tailoring intermediates adsorption behaviors•A selective switch for CO2 electroreduction at an industrial current density level•Comprehensive understanding of CO2RR pathways for different productsSummaryMass production of Au–Cu-based catalysts with tailored selectivity is a complex and challenging task. We report a semi-affinity strategy to realize the synthesis of Au–Cu Janus nanocrystals with continuously tuned interfaces (from dimer, Janus, acorn-like Janus, to core-shell) based on Au nanosphere seeds. We highlight the role of interfacial strain due to a large lattice mismatch in growth control. The systematic electrochemical evaluation shows that the interfacial Cu oxide state, ∗CO coverage, and intermediate adsorption configuration can be well tuned by tailoring the Janus nanostructure. Optimized Au–Cu Janus catalyst reaches an efficiency of up to 80.0% for C2+ product with a partial current density of 466.1 mA cm−2. The reaction products can be selectively switched from methanol (dimer) to ethanol (Janus) and further to ethylene (acorn-like Janus) by increasing the interface area of the Au–Cu heterostructures. The catalytic mechanisms are unraveled by operando surface-enhanced Raman spectroscopy (SERS) analysis and density functional theory calculations.Graphical abstract