Electrochemical CO 2 reduction reaction (CO 2 RR) offers a promising strategy for CO 2 conversion into value-added C 2+ products and facilitates the storage of renewable resources under comparatively mild conditions, but still remains a challenge. Herein, we propose the strategy of surface reconstruction and interface integration engineering to construct tuneable Cu 0 –Cu + –Cu 2+ sites and oxygen vacancy oxide derived from CeO 2 /CuO nanosheets (OD-CeO 2 /CuO NSs) heterojunction catalysts and promote the activity and selectivity of CO 2 RR. The optimized OD-CeO 2 /CuO electrocatalyst shows the maximum Faradic efficiencies for C 2+ products in the H-type cell, which reaches 69.8% at −1.25 V versus a reversible hydrogen electrode (RHE). Advanced characterization analysis and density functional theory (DFT) calculations further confirm the fact that the existence of oxygen vacancies and Cu 0 –Cu + –Cu 2+ sites modified with CeO 2 is conducive to CO 2 adsorption and activation, enhances the hydrogenation of *CO to *CHO, and further promotes the dimerization of *CHO, thus promoting the selectivity of C 2+ generation. This facile interface integration and surface reconstruction strategy provides an ideal strategy to guide the design of CO 2 RR electrocatalysts.
Phenols are important building blocks widely applied in many fields. The pronounced orientational effect of the phenolic hydroxyl group makes achieving selective synthesis of meta -phenols challenging. Accessing meta -phenols needs lengthy synthetic sequences. Herein, we first developed a heterogeneous CO 2 -mediated CeO 2 -5CuO catalyst for decarboxylative oxidation of benzoic acids with a more than 80% selectivity to meta -phenols. This technology is based on a traceless directing group relay method. The CeO 2 -CuO catalysts with different Ce/Cu ratios exhibited controllable reaction selectivity between decarboxylation and decarboxylative oxidation. Spectroscopy experiments and computational studies showed the adsorption state of benzoic acid was found to be crucial for subsequent reaction pathways. The moderate adsorption on CO 2 -mediated CeO 2 -5CuO catalyst contributes to the distinct selectivity of phenol. Furthermore, the paddlewheel intermediate facilitates the synthesis of meta -phenols from benzoic acids. This traceless directing group method would promote the development of useful one-pot meta -substituted phenols from bio-based benzoic acids.
Summary Phenolic chemicals are important building blocks in chemical and material industries. In this protocol, we describe the preparation of CeO 2 -CuO catalysts and the application in the decarboxylative oxidation reaction of benzoic acids to phenols. Furthermore, we describe how to modify the basic sites of CeO 2 -CuO catalysts by CO 2 treatment to increase the selectivity of phenol and the regeneration process of used catalyst. For complete details on the use and execution of this protocol, please refer to Du et al. (2023). 1
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