Cu+-Driven Formate Selectivity in Oxidation-State-Dependent CO2 Reduction on Cu2O|Graphene
- Type
- Article
- Citation
- Small
- Issued Date
- ACCEPT
- Abstract
- Electrochemical CO2 reduction to formate on copper oxide catalysts is often limited by poor selectivity due to competing multi-electron pathways and by rapid reduction of active sites accompanied by severe structural reconstruction under cathodic bias. Here, we report a well-defined Cu2O|graphene heterostructure that enables highly selective CO2-to-formate conversion while maintaining a Cu+-state active phase during electrocatalysis. The electrochemical reactivity of distinct Cu oxidation states (Cu0, Cu+, and Cu2+) supported on graphene was systematically compared, revealing pronounced oxidation-state-dependent CO2 reduction behavior. Strong electronic coupling at the Cu2O|graphene interface regulated interfacial electron transfer, suppressing over-reduction to metallic Cu and preserving the catalytic structure during electrolysis. Time-resolved ex situ X-ray diffraction, Cu LMM Auger spectroscopy, Cu K-edge XANES, in situ Raman spectroscopy and high-resolution transmission electron microscopy collectively suggested the retention of Cu+-rich environment on graphene during CO2RR, in contrast to Cu|graphene and CuO|graphene. Consequently, stabilized Cu+ sites at the Cu2O|graphene interface favored a proton-coupled electron transfer pathway via the *OCHO intermediate, delivering a high formate Faradaic efficiency of 78% at −0.86 V vs. RHE. This work establishes interfacial electronic coupling as an effective strategy to stabilize metastable Cu+ active sites for selective CO2-to-formate conversion.
- Publisher
- Wiley - V C H Verlag GmbbH & Co.
- ISSN
- 1613-6810
- Appears in Collections:
- Department of Chemistry > 1. Journal Articles
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