Synergistic regulation of hydrophobicity and basicity for copper hydroxide‐derived copper to promote the CO₂ electroreduction reaction

Abstract

A simple method was proposed to activate alkaline Cu(OH) 2 with an acidic ionomer, Nafion, to regulate its surface microenvironment, including hydrophobicity and local basicity. In particular, the direct complete neutralization reaction between Cu(OH) 2 and Nafion in aqueous solution induces the exposing of vast anions which can exclude the in-situ-formed hydroxides and raise the local basicity. Remarkably, the optimal Nafionactivated Cu(OH) 2 -derived Cu can efficiently suppress the hydrogen evolution reaction (HER) and improve the selectivity for multi-carbon products in the CO 2 electroreduction reaction (eCO 2 RR). The H 2 Faradaic efficiency (FE) decreased to 11% at a current density of 300 mA/cm 2 (−0.76 V vs. RHE) in a flow cell, while the bare one with H 2 had an FE of 40%. The total eCO 2 RR FE reaches as high as 83%, along with an evidently increased C 2 H 4 FE of 44% as compared with the bare one (24%), and good stability (8000 s), surpassing that of most of the reported Cu(OH) 2 -derived Cu. The experimental and theoretical results both show that the strong hydrophobicity and high local basicity jointly boosted the eCO 2 RR as acquired by felicitously introducing ionomer on the Cu (OH) 2 -derived Cu surface.

Multi-functional integrated design of a copper foam-based cathode for high-performance lithium–oxygen batteries

“…The diffraction peak located at 53°can be attributed to the Cu(OH) 2 (PDF#80-0656) nanowires asgrown on the CuFo substrate. 21,22 For CuFo-Cu@C/Au NWs, CuFo-Cu@C NWs without Au nanoparticles (SEM in Fig. S5 †) and CuFo-Cu/Au without the protective carbon layer (SEM in Fig.…”

Promoting CO2 Electroreduction to Ethane by Iodide-Derived Copper with the Hydrophobic Surface

“…The construction of hydrophobic surface is an effective strategy to change the local microenvironment of the catalysts to promote CO 2 mass transfer and inhibit HER. Polymers, , ionic polymers, − and organic molecules , that containing −CH 2 – or −CF 2 - mainchains can help increase the hydrophobicity of surface for promoting the local concentrations of CO 2 . Moreover, the surface hydrophobicity is closely related to the formation of •OH radicals, a strong oxidant formed in HCO 3 – electrolyte, that favors the fast reoxidation of Cu 0 to Cu δ+ (0 < δ < 2) species for strengthening the cooperation of Cu 0 and Cu δ+ …”

Tailoring Microenvironments and In Situ Transformations of Cu Catalysts for Selective and Stable Electrosynthesis of Multicarbon Products

“…In particular, increasing the hydrophobicity of organic binder coatings can enhance the local OH − concentration and CO 2 /H 2 O concentration ratio, which contributes to improved selectivity. [10][11][12] In another example, a double layer of both anion-and cationconducting ionomers was introduced on the Cu surface to regulate the water concentration and to increase local pH by trapping hydroxide ions (OH − ), which resulted in significant suppression of the hydrogen evolution reaction (HER) and a record high 90% Faradaic efficiency of C 2+ products. [13] Alongside product selectivity, the poor long-term durability of Cu-based catalysts introduces another significant barrier to sustainable generation of C 2+ products from CO 2 R. Indeed, bare Cubased catalysts have been shown to be unstable when subjected to continuous CO 2 electrolysis.…”

“…Although various inorganic or organic coatings have been explored to enhance both the C 2+ product selectivity and stability of Cu-based catalysts, [11,15] understanding the impact of the most widely used binder-Nafion-is only now emerging. [12,[16][17][18][19][20][21][22][23] Recently, we reported that the activity, selectivity, and stability of CO 2 R can be drastically impacted by engineering the internal structure and properties of Nafion ionomer coatings on oxidederived Cu catalysts supported on carbon paper. [24] Importantly, thin layers of Nafion can beneficially stabilize the catalyst and create favorable microenvironments for CO 2 R, but can also lead to the blocking of active sites or introduce undesired mass transport limitations.…”