Understanding the structural and compositional sensitivities of the electrochemical CO2 reduction reaction (CO2RR) is fundamentally important for developing highly efficient and selective electrocatalysts. Here, we use Ag/Cu nanocrystals to uncover the key role played by the Ag/Cu interface in promoting CO2RR. Nanodimers including the two constituent metals as segregated domains sharing a tunable interface are obtained by developing a seeded growth synthesis, wherein preformed Ag nanoparticles are used as nucleation seeds for the Cu domain. We find that the type of metal precursor and the strength of the reducing agent play a key role in achieving the desired chemical and structural control. We show that tandem catalysis and electronic effects, both enabled by the addition of Ag to Cu in the form of segregated nanodomain within the same catalyst, synergistically account for an enhancement in the Faradaic efficiency for C2H4 by 3.4-fold and in the partial current density for CO2 reduction by 2-fold compared with the pure Cu counterpart. The insights gained from this work may be beneficial for designing efficient multicomponent catalysts for electrochemical CO2 reduction.

Synergistic effects at metal/metal oxide interfaces often give rise to highly active and selective catalytic motifs. So far, such interactions have been rarely explored to enhance the selectivity in the electrochemical CO 2 reduction reaction (CO 2 RR). Herein, Cu/CeO 2-x heterodimers (HDs) are synthesized and presented as one of the prime examples where such effects promote CO 2 RR. A colloidal seeded-growth synthesis is developed to connect the two highly mismatched domains (Cu and CeO 2-x) through an interface. The Cu/CeO 2-x HDs exhibit state-of-the-art selectivity towards CO 2 RR (up to ~80%) against the competitive hydrogen evolution reaction (HER) and high faradaic efficiency for methane (up to ~54%) at-1.2 V RHE , which is 5 times higher than that obtained when the Cu and CeO 2-x nanocrystals are physically mixed. Operando X-Ray absorption spectroscopy along with other ex-situ spectroscopies evidences the partial reduction from Ce 4+ to Ce 3+ in the HDs during CO 2 RR. A Density Functional Theory (DFT) study of the active site motif in reducing condition reveals synergistic effects in the electronic structure at the interface. The proposed lowest free energy pathway utilizes O-vacancy site with intermediates binding to both Cu and Ce atoms, a configuration which allows to break the CHO*/CO* scaling relation. The suppression of HER is attributed to the spontaneous formation of CO* at this interfacial motif and subsequent blockage of the Cu-sites.

The use of molecular modulators to reduce the defect density at the surface and grain boundaries of perovskite materials has been demonstrated to be an effective approach to enhance the photovoltaic performance and device stability of perovskite solar cells. Herein, we employ crown ethers to modulate perovskite films, affording passivation of undercoordinated surface defects. This interaction has been elucidated by solid-state nuclear magnetic resonance and density functional theory calculations. The crown ether hosts induce the formation of host–guest complexes on the surface of the perovskite films, which reduces the concentration of surface electronic defects and suppresses nonradiative recombination by 40%, while minimizing moisture permeation. As a result, we achieved substantially improved photovoltaic performance with power conversion efficiencies exceeding 23%, accompanied by enhanced stability under ambient and operational conditions. This work opens a new avenue to improve the performance and stability of perovskite-based optoelectronic devices through supramolecular chemistry.

It could successfully control the band-bending of the perovskite semiconductor, which led to improvement of the photovoltaic performance.