ABSTRACT
Electrocatalytic CO2 reduction into value-added multicarbon products offers a means to close the anthropogenic carbon cycle using renewable electricity. However, the unsatisfactory catalytic selectivity for multicarbon products severely hinders the practical application of this technology. We report a cascade AgCu single-atom and nanoparticle electrocatalyst, in which Ag nanoparticles produce CO and AgCu single-atom alloys promote C-C coupling kinetics. As a result, a Faradaic efficiency (FE) of 94 ± 4 % toward multicarbon products is achieved with the as-prepared AgCu single-atom and nanoparticle catalyst under ~720 mA cm-2 working current density at -0.65V in a flow cell with alkaline electrolyte. Density functional theory calculations further demonstrate that the high multicarbon product selectivity results from cooperation between AgCu single-atom alloys and Ag nanoparticles, wherein the Ag single-atom doping of Cu nanoparticles increases the adsorption energy of *CO on Cu sites due to the asymmetric bonding of the Cu atom to the adjacent Ag atom with a compressive strain.
Electrocatalytic nitrate reduction reaction (NO3–RR) technology provides a promising solution to recover the nitrate nutrition from wastewater through catalyzing nitrate reduction into value-added NH3. However, the selectivity and efficiency of electrocatalysts are frustrated due to the imbalance of *H adsorption (for NO3 hydrogenation) and unavoidable adjacent *H self-coupling on active sites, resulting in competitive hydrogen evolution reaction (HER). Here, we report a PdCu single-atom alloy (SAA) catalyst that allows isolated Pd sites to produce *H for the hydrogenation process of *NO3 on neighboring Cu sites, which can restrain the *H self-coupling through extending the distance between two *H and thus effectively suppress competitive HER. Consequently, the PdCu SAA catalyst exhibits an ultrahigh NH3 Faraday efficiency (FE) of 97.1% with a yield of 15.4 μmol cm–2 h–1 from the electrocatalytic NO3–RR in the neutral electrolyte, outperforming most of the reported catalysts. Single-crystal experiments and theoretical calculations further prove that the introduction of atomic Pd on the Cu (100) surface could serve as the main active site and greatly decrease the energy barrier of the rate-determining step (RDS) on Cu om ΔG = 0.39 eV (*NOO → *NOOH) to ΔG = 0.10 eV of *NOH → *NHOH on PdCu SAA.
BIOGRAPHY
Prof. Yimin Wu is an Inaugural Tang Family Chair Assistant Professor in the University of Waterloo Department of Mechanical and Mechatronics Engineering and Waterloo Institute for Nanotechnology, where he is also Director of the Materials Interfaces Foundry. After receiving his DPhil degree in Materials from the University of Oxford in 2013, he won a prestigious SinBeRise Postdoctoral Fellowship to conduct energy storage studies at the University of California, Berkeley, and Lawrence Berkeley National Laboratory. In 2014, he joined the Argonne National Laboratory Center for Nanoscale Materials and Joint Center for Energy Storage Research – the largest of its kind in North America - and was a research assistant professor at University of Illinois until 2019.
Prof. Wu has authored over 100 papers in top journals, including Nature, Nature Energy, and Nature communications.
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