(668f) Interfacial Engineering of Au/CuxOyHz Heterostructures for Efficient Photocatalytic CO2 Reduction: Insights from Theoretical Approaches

Metal nanoparticles (NPs) consisting of copper (Cu) and gold (Au) have recently gained significant interest for their potential use in plasmon-induced photochemical reactions [1]. However, the exact oxidation state of Cu (0/+1/+2) at the operation conditions and the direction of electron/hole transfer between Au (plasmonic NP) and Cu NP remain under debate. Therefore, an accurate theoretical description to understand the interface effects is of both fundamental and practical interest. In this study, we combined computational and experimental efforts to elucidate the oxidation states of Cu when deposited onto an Au substrate for efficient photocatalytic CO₂ reduction reaction. Analysis of the XAS data of Cu particles confirmed primarily composition of Cu₂O and Cu(II) species, with no detectable metallic Cu present, when exposed to air. Based on this, we investigated the interfacial phenomena of Au/CuO, Au/Cu₂O, and Au/Cu(OH)₂ using the framework of density functional theory (DFT) to gain insights into the atomistic properties, such as stability, band bending, work function, charge transfer and CO₂ conversion. We computed ab-initio thermodynamics to identify low-energy surface structures that are most stable under realistic catalytic conditions. Furthermore, we have extracted the band-edge alignment for all possible thermodynamically stable configurations, that suggest the possibility of electron transfer from Cu₂O to Au occurs until the Fermi level aligns (Figure 1). Then, we explored CO₂ adsorption across different Au/Cu_xO_yH_z heterostructures. Our study highlights the potential of plasmonic heterostructure photocatalysts to convert solar energy into chemical fuels through selective and unassisted gas-phase photocatalytic CO₂ reduction.

This work is performed by the Liquid Sunlight Alliance, which is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Fuels from Sunlight Hub under Award Number DESC0021266.

[1] H. A. Atwater et al. ACS Energy Lett, 6, 1849 (2021)