Field-induced reagent concentration and sulfur adsorption enable efficient electrocatalytic semihydrogenation of alkynes

Abstract

Efficient electrocatalytic alkyne semihydrogenation with potential/time-independent selectivity and Faradaic efficiency (FE) is vital for industrial alkene productions. Here, sulfur-tuned effects and field-induced reagent concentration are proposed to promote electrocatalytic alkyne semihydrogenation. Density functional theory calculations reveal that bulk sulfur anions intrinsically weaken alkene adsorption, and surface thiolates lower the activation energy of water and the Gibbs free energy for H* formation. The finite element method shows high-curvature structured catalyst concentrates K + by enhancing electric field at the tips, accelerating more H* formation from water electrolysis via sulfur anion–hydrated cation networks, and promoting alkyne transformations. So, self-supported Pd nanotips with sulfur modifiers are developed for electrochemical alkyne semihydrogenation with up to 97% conversion yield, 96% selectivity, 75% FE, and a reaction rate of 465.6 mmol m −2 hour −1 . Wide potential window and time irrelevance for high alkene selectivity, good universality, and easy access to deuterated alkenes highlight the promising potential.

Electrochemical Upgrading of Formic Acid to Formamide via Coupling Nitrite Co-Reduction

“…The sextet peaks (denoted as #) indexed to carbon radicals can be detected only when formic acid and applied potential coexist, confirming the successful activation and reduction of formic acid and implying the generation of *CHO intermediates catalyzed by ER–Cu . Under reduction conditions (−0.4 V vs RHE), the other peaks are attributed to hydrogen radicals . For nitrite reduction, the signals of m / z 33, 17, and 2 are detected by online DEMS, proving the existence of NH 2 OH, NH 3 , and H 2 (Figure d), respectively.…”

“…43 Under reduction conditions (−0.4 V vs RHE), the other peaks are attributed to hydrogen radicals. 44 For nitrite reduction, the signals of m/z 33, 17, and 2 are detected by online DEMS, proving the existence of NH 2 OH, NH 3 , and H 2 (Figure 5d), respectively. Based on these results and previous reports, we can obtain the pathway of coupling reaction as well as sole formic acid and nitrite reduction (Figure 5e).…”

A dynamic piezoelectric effect to promote electrosynthesis of hydrogen peroxide

“…Hereafter, based on the as-calculated surface electric fields of different ceramic catalysts, we simulated the concentration distributions of different ions within the electric double layers (EDLs) using the Gouy–Chapman–Stern model, 23,24,57 which is composed of a Helmholtz layer and a diffusion layer. In the current work, a monolayer of surface-adsorbed hydrated potassium ions made up the Helmholtz layer, while the diffusion layer comprises both cations and anions presenting a free diffusion in the electrolyte, which was established on the basis of a dynamic equilibrium between electrostatic forces and diffusion.…”

Economically viable electrocatalytic ethylene production with high yield and selectivity

“…To design a suitable electrode with relatively high ethylene FE and yield, three factors should be considered: (1) low activation energy for water dissociation and small Gibbs free energy (ΔG H* ) for H * formation 33,34 ; (2) high energy barriers for H * coupling to suppress competitive HER; and (3) easy desorption of ethylene to avoid overhydrogenation and C-C coupling 35,36…”