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1. Revealing Coexisting Cu ⁰ –Cu ⁺ Sites in Cu ₃ N Nanoensembles for Selective CC Coupling of CO ₂ Under Low Overpotential

   https://doi.org/10.1002/cssc.202500003  

   Li, Junrui; Zhong, Hong; Hong_Lee, Soo; Li, Hui; Drisdell, Walter_S; Dun, Chaochao; Burciaga, Rihana; Ingram, Conrad; Beckman, Scott_P; Urban, Jeffrey_J; et al (June 2025, ChemSusChem)

   To address a long‐existing debate on what copper species are responsible for efficient CC coupling, especially ethanol formation, in electrochemical CO₂reduction reaction, herein, a comprehensive study using Cu₃N nanocubes with a uniform size and shape, alongside a single crystalline phase is reported. The Cu₃N nanoensemble electrode has a remarkable Faradaic efficiency (FE) of 64% for ethanol production at a relatively low potential of −0.6 V versus reversible hydrogen electrode. Throughin‐operandoX‐ray absorption spectroscopy study, a dynamic phase evolution that directly correlates with changes in FE across varying applied potentials is observed. Notably, the nanoensemble with a composition of ≈71% Cu⁺and 29% Cu⁰is identified as being selective for ethanol formation at the low overpotential. Conversely, a predominantly metallic Cu phase formed at potentials more negative than −0.6 V favors the hydrogen evolution reaction. Density functional theory calculations at the Cu₃N–Cu interface substantiate that the coexistence of Cu⁰–Cu⁺not only energetically favors the ethanol reaction pathway but also destabilizes the intermediates for ethylene pathway. 

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2. Photoelectron Spectroscopy and Theoretical Study of Di-Copper–Boron Clusters: Cu ₂ B ₃ ^– and Cu ₂ B ₄ ^–

   https://doi.org/10.1021/acs.jpca.3c02417  

   Pozdeev, Anton S.; Chen, Wei-Jia; Choi, Hyun Wook; Kulichenko, Maksim; Yuan, Dao-Fu; Boldyrev, Alexander I.; Wang, Lai-Sheng (June 2023, The Journal of Physical Chemistry A)
3. Encapsulation of tricopper cluster in a synthetic cryptand enables facile redox processes from Cu ^I Cu ^I Cu ^I to Cu ^II Cu ^II Cu ^II states

   https://doi.org/10.1039/D0SC05441K  

   Zhang, Weiyao; Moore, Curtis E.; Zhang, Shiyu (March 2021, Chemical Science)

   null (Ed.)

   One-pot reaction of tris(2-aminoethyl)amine (TREN), [Cu I (MeCN) 4 ]PF 6 , and paraformaldehyde affords a mixed-valent [ TREN4 Cu II Cu I Cu I (μ 3 -OH)](PF 6 ) 3 complex. The macrocyclic azacryptand TREN4 contains four TREN motifs, three of which provide a bowl-shape binding pocket for the [Cu 3 (μ 3 -OH)] 3+ core. The fourth TREN caps on top of the tricopper cluster to form a cryptand, imposing conformational constraints and preventing solvent interaction. Contrasting the limited redox capability of synthetic tricopper complexes reported so far, [ TREN4 Cu II Cu I Cu I (μ 3 -OH)](PF 6 ) 3 exhibits several reversible single-electron redox events. The distinct electrochemical behaviors of [ TREN4 Cu II Cu I Cu I (μ 3 -OH)](PF 6 ) 3 and its solvent-exposed analog [ TREN3 Cu II Cu II Cu II (μ 3 -O)](PF 6 ) 4 suggest that isolation of tricopper core in a cryptand enables facile electron transfer, allowing potential application of synthetic tricopper complexes as redox catalysts. Indeed, the fully reduced [ TREN4 Cu I Cu I Cu I (μ 3 -OH)](PF 6 ) 2 can reduce O 2 under acidic conditions. The geometric constraints provided by the cryptand are reminiscent of Nature's multicopper oxidases (MCOs). For the first time, a synthetic tricopper cluster was isolated and fully characterized at Cu I Cu I Cu I ( 4a ), Cu II Cu I Cu I ( 4b ), and Cu II Cu II Cu I ( 4c ) states, providing structural and spectroscopic models for many intermediates in MCOs. Fast electron transfer rates (10 5 to 10 6 M −1 s −1 ) were observed for both Cu I Cu I Cu I /Cu II Cu I Cu I and Cu II Cu I Cu I /Cu II Cu II Cu I redox couples, approaching the rapid electron transfer rates of copper sites in MCO. 

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4. Probing copper-boron interactions in the Cu ₂ B ₈ ⁻ bimetallic cluster

   https://doi.org/10.1116/6.0001833  

   Kulichenko, Maksim; Chen, Wei-Jia; Choi, Hyun Wook; Yuan, Dao-Fu; Boldyrev, Alexander I.; Wang, Lai-Sheng (July 2022, Journal of Vacuum Science & Technology A)

   Borophenes are atom-thin boron layers that can be grown on coinage metal substrates and have become an important class of synthetic 2D nanomaterials. The interactions between boron and substrates are critical to understand the growth mechanisms of borophenes. Here, we report an investigation of copper-boron interactions in the Cu 2 B 8 − bimetallic cluster using photoelectron spectroscopy and quantum chemical calculations. Well-resolved photoelectron spectra are obtained at several photon energies and are combined with theoretical calculations to elucidate the structures and bonding of Cu 2 B 8 − . Global minimum searches reveal that Cu 2 B 8 − consists of a Cu 2 dimer atop a B 8 molecular wheel with a long Cu–Cu bond length close to that in Cu 2 + . Chemical bonding analyses indicate that there is clear charge transfer from Cu 2 to B 8 , and the Cu 2 B 8 − cluster can be viewed as a [Cu 2 + ]-borozene complex, [Cu 2 + ][B 8 2– ]. In the neutral cluster, no Cu–Cu bond exists and Cu 2 B 8 consists of two Cu + centers interacting with doubly aromatic B 8 2− borozene. The charge transfer interactions between Cu and boron in the Cu 2 B 8 − cluster are analogous to charge transfer from the copper substrate to the first borophene layer recently reported to be critical in the growth of bilayer borophenes on a Cu(111) substrate. 

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5. Methane C–H Activation by [Cu ₂ O] ²⁺ and [Cu ₃ O ₃ ] ²⁺ in Copper-Exchanged Zeolites: Computational Analysis of Redox Chemistry and X-ray Absorption Spectroscopy

   https://doi.org/10.1021/acs.inorgchem.0c03693  

   Suleiman, Olabisi; Panthi, Dipak; Adeyiga, Olajumoke; Odoh, Samuel O. (May 2021, Inorganic Chemistry)

   null (Ed.)