Calixarene-Functionalized Stable Bismuth Oxygen Clusters for Specific CO₂-to-HCOOH Electroreduction

Abstract

Designing and synthesizing well-defined crystalline catalysts for long-term electrocatalytic conversion of CO 2 to specific products remain a great challenge. In this work, two very stable crystalline bismuth oxygen clusters functionalized by hydrophobic p-tertbutylthiacalix[4]arene ligand, Bi 3 and Bi 14 , were constructed and treated as catalysts for efficient electrochemical CO 2 reduction. Sandwich-type Bi 3 with synergistic bi-bismuth exhibits a remarkable performance for CO 2 -to-HCOOH conversion with a faradaic efficiency (FE HCOOH ) of 96.47% at −1.3 V (vs reversible hydrogen electrode) and durability over 27.5 h, while rodlike Bi 14 with a monobismuth active site reached a maximum FE HCOOH of 92.76% at −1.2 V with durability over 23.9 h. Density functional theory calculation proves that adjacent double active bismuth atoms in Bi 3 are more beneficial to stabilize the *OCHO intermediate and then promote the electrocatalytic reduction of CO 2 to HCOOH than Bi 14 with a single active site. This work represents the report of stable crystalline bismuth-oxo cluster catalysts for specific electrocatalytic CO 2 reduction conversion.

Calix[4]arene-Functionalized Titanium-Oxo Compounds for Perceiving Differences in Catalytic Reactivity Between Mono- and Multimetallic Sites

“…The simultaneous appearance of absorption peaks at 1240 and 1608 cm –1 indicated the formation of carboxylate (CO 2 δ− ) . The absorption peaks located at 1693, 1747, 1766, and 1785 cm –1 were probably from formic acid …”

“…56 The absorption peaks located at 1693, 1747, 1766, and 1785 cm −1 were probably from formic acid. 57 To gain more insights into the photocatalytic mechanism, DFT calculations related to CO 2 adsorption and activation were carried out for Ti 16 -C4A and Ti-C4A (see the Supporting Information for details). Considering that Ti 16 -C4A and Ti-C4A behave as heterogeneous catalysts, the reaction mechanism should be studied through the solid surface rather than individual molecules.…”

Electron delocalization of robust high-nuclear bismuth-oxo clusters for promoted CO2electroreduction

“…BiOC-4 presents a TOF of 276.59 h −1 for HCOOH formation at −1.1 V, while BiOC-5 shows an impressive reaction rate with a TOF of 405.7 h −1 at −1.1 V, which outperforms the performance of crystalline Bi-based electrocatalysts. 46,47 Catalytic durability is one of the crucial parameters for evaluating the application potential of electrocatalysts. Therefore, a longtime electrolysis experiment was performed at a potential of −0.95 V. The current curve illustrates that BiOC-5 can keep the current density roughly unchanged in a 24 h reaction (Fig.…”

Selective Reduction of CO2 to Methanol via Hydrosilylation Boosted by a Porphyrinic Metal–Organic Framework

“…CO 2 recycling and reductive conversion are essential to build a sustainable society. − As a kind of green and clean energy, hydrogen is usually employed to reduce CO 2 to obtain formic acid, formaldehyde, and methanol . Among different C1 reduced products, methanol is the most important with regard to chemical, pharmaceutical, fuel, and other applications. − Although CO 2 hydrogenation to methanol is thermodynamically favored (Δ G 298 K = −2.3 kcal mol –1 ), the reaction generally requires high temperatures (>200 °C) and high pressures (with the net pressure of CO 2 and H 2 being higher than 40 bar) due to complicated kinetics .…”