Structurally ordered intermetallic nanocrystals (NCs) and single-atom catalysts (SACs) are two emerging catalytic motifs for sustainable chemical production and energy conversion. However, both have synthetic limitations which can lead to the aggregation of NCs or metal atoms. Single-atom alloys (SAAs), which contain isolated metal atoms in a host metal, can overcome the aggregation concern because of the thermodynamic stabilization of single atoms on host metal surfaces. Here we report a direct solution-phase synthesis of Cu/CuAu core/shell NCs with tunable SAA layers. This synthesis can be extended to other Cu/CuM (M = Pt, Pd) systems, in which M atoms are isolated in the copper host. Using this method, the density of SAAs on a copper surface can be controlled, resulting in both low and high densities of single atoms. Alloying gold into the copper matrix introduced ligand effects that optimized the chemisorption of *NO3 and *N. As a result, the densely packed Cu/CuAu material demonstrated a high selectivity toward NH3 from the electrocatalytic nitrate reduction reaction with an 85.5% Faradaic efficiency while maintaining a high yield rate of 8.47 mol h−1 g−1. This work advances the design of atomically precise catalytic sites by creating core/shell NCs with SAA atomic layers, opening an avenue for broad catalytic applications.
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H.Y.Z., Q.G., X.H., Y.L. and B.M. acknowledge funding support from the NSF CBET Catalysis CAREER programme (award number 2143710). This research used resources of the Advanced Photon Source, a US Department of Energy (DOE) Office of Science user facility operated for the DOE Office of Science by Argonne National Laboratory under contract number DE-AC02-06CH11357. Q.H. acknowledges the support of the National Research Foundation (NRF) Singapore, under its NRF Fellowship (NRF-NRFF11-2019-0002) and the Singapore Low-carbon Energy Research funding initiative (award number LCERFI01-0017). This research used the beamline 7-BM (QAS) of the National Synchrotron Light Source II, a US DOE Office of Science User Facility operated for the DOE Office of Science by the Brookhaven National Laboratory under contract number DE-SC0012704. S.Z. and S.-W.Y. gratefully acknowledge the financial support for this research provided by the NSF (grant number CBET-2004808). H.S.P and H.X. gratefully acknowledge the financial support of the NSF CAREER programme (CBET-1845531). The computational resource used in this work is provided by the advanced research computing at Virginia Polytechnic Institute and State University.
The authors declare no competing interests.
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Source Data Fig. 3
Source Data Fig. 4
Electrocatalytic nitrate reduction performance.
Source Data Fig. 5
Density functional theory calculations.
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Gao, Q., Yao, B., Pillai, H.S. et al. Synthesis of core/shell nanocrystals with ordered intermetallic single-atom alloy layers for nitrate electroreduction to ammonia. Nat. Synth (2023). https://doi.org/10.1038/s44160-023-00258-x
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