Graphite-Conjugated Rhenium Catalysts for Carbon Dioxide Reduction

Abstract

Condensation of fac-Re(5,6-diamino-1,10-phenanthroline)(CO)3Cl to o-quinone edge defects on graphitic carbon surfaces generates graphite-conjugated rhenium (GCC-Re) catalysts that are highly active for CO2 reduction to CO in acetonitrile electrolyte. X-ray photoelectron and X-ray absorption spectroscopies establish the formation of surface-bound Re centers with well-defined coordination environments. GCC-Re species on glassy carbon surfaces display catalytic currents greater than 50 mA cm(-2) with 96 ± 3% Faradaic efficiency for CO production. Normalized for the number of Re active sites, GCC-Re catalysts exhibit higher turnover frequencies than that of a soluble molecular analogue, fac-Re(1,10-phenanthroline)(CO)3Cl, and turnover numbers greater than 12,000. In contrast to the molecular analogue, GCC-Re surfaces display a Tafel slope of 150 mV/decade, indicative of a catalytic mechanism involving rate-limiting one-electron transfer. This work establishes graphite-conjugation as a powerful strategy for generating well-defined, tunable, heterogeneous electrocatalysts on ubiquitous graphitic carbon surfaces.

A General Two‐Step Strategy–Based High‐Throughput Screening of Single Atom Catalysts for Nitrogen Fixation

“…However, molecular catalysts generally exhibit poorer durability and are less readily incorporated into electrolyzers in comparison with heterogeneous catalysts. [48,49] Among heterogeneous catalysts, N-G-supported SACs possess similar active centers to that of the molecular catalysts for NRR ( Figure 1b). Therefore, investigation on the catalytic activity of N-G supported SACs for NRR is of great importance.…”

“…For NRR, several molecular catalysts, such as Fe‐, Co‐ and Mo‐nitride complexes, have been prepared, where the MN x moieties serve as the active centers ( Figure a). However, molecular catalysts generally exhibit poorer durability and are less readily incorporated into electrolyzers in comparison with heterogeneous catalysts . Among heterogeneous catalysts, N–G‐supported SACs possess similar active centers to that of the molecular catalysts for NRR (Figure b).…”

Electrocatalytic Metal–Organic Frameworks for Energy Applications

“…Depending on the methodo fi mmobilization, the heterogenized molecular catalystc an be removed from the electrode surfacea nd reused, whichi sn ecessary for energy-converting applications. Covalent attachment, [22][23][24][25] electropolymerization, [26][27][28][29][30] and adsorption/noncovalent attachment of metal complexes [31][32][33][34][35] are methods of heterogenizing molecular catalysts for energy-conversion applications and were reviewed elsewhere. [36][37][38]…”

Molecular-Level Insights into Oxygen Reduction Catalysis by Graphite-Conjugated Active Sites

“…We have shown that this functionalization method generates graphite-conjugated catalysts (GCCs) that display high activity for the ORR in alkaline aqueous media, and that the activity of these GCCs is sensitive to the structure of the molecular fragment incorporated. 45,48 Our initial synthetic studies of structure-activity correlations on GCCs identified carbon surfaces treated with aryl-pyridinium-substituted diamines, dubbed N + -GCCs, to be particularly active for the ORR (Scheme 1). 45 With well-defined catalytic sites and appreciable activity, N + -GCCs are an ideal platform for detailed experimental investigations of the kinetics of ORR catalysis.…”