Ruthenium Complexes in Homogeneous and Heterogeneous Catalysis for Electroreduction of CO₂

Abstract

We have studied two structurally related, water‐insoluble ruthenium complexes [RuII(tpy*)(phenCO2)](PF6) (1) (tpy*=5,4′,5′′‐tri‐tert‐butyl‐2,2′;6′,2′′‐terpyridine; phenCO2H=1,10‐phenanthroline‐2‐carboxylic acid) and [RuII(tpy)(dmphen)(Cl)](PF6) (2) (tpy=2,2′;6′,2′′‐terpyridine; dmphen=2,9‐dimethyl‐1,10‐phenanthroline, also known as neocuproine) and their electrocatalytic activity for CO2 reduction in acetonitrile and after immobilization on the reduced graphene oxide (rGO) in water (pH 7.2). Under homogeneous conditions (in CO2 saturated acetonitrile solution), characteristic major CO2 reduction waves indicate ∼280 mV lower overpotential upon changing the catalyst from 1 to 2. The higher CO2 electroreduction performance of 2 is also reflected on the heterogeneous rGO surfaces.

Vitamin B12 on Graphene for Highly Efficient CO2 Electroreduction

“…Stability is an important issue for these types of hybrid systems. 25 The potential solubility issue was first checked due to the soluble nature of VitB 12 in water. No peaks were observed corresponding to VitB 12 in the 400 MHz 1 H NMR spectra after electrolysis, indicating that there was almost no leaching of VitB 12 from the hybrid system (Figure S7).…”

“…Stability is an important issue for these types of hybrid systems . The potential solubility issue was first checked due to the soluble nature of VitB 12 in water.…”

Cobalt Electrocatalyst on Fluorine Doped Carbon Cloth – a Robust and Partially Regenerable Anode for Water Oxidation

“…[5][6][7] Both homogeneous and heterogeneous electrochemical systems have been investigated in this context. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] Among them, to date, ruthenium-based electrocatalysts have shown the best turnover numbers (TONs) and turnover frequencies (TOFs) for water splitting. [17,18,22] Their high price and environmental impact represent critical disadvantages that could come to limit their applicability.…”

“…Encouragingly, exciting progress has been made in recent years regarding the immobilization or anchoring of molecular WO catalysts onto conductive supports. [16][17][18][19][20][21]24] This strategy takes advantage of both the mechanistic understanding obtained from molecular systems, and the improved stability typically observed for catalysts immobilized on a conductive surface.…”

“…Here, the oxidation of water constitutes the major bottleneck of this overall process but we have witnessed exciting development in the area of water oxidation, both in terms of energy efficiency and sustainability over the past decades [5–7] . Both homogeneous and heterogeneous electrochemical systems have been investigated in this context [8–22] . Among them, to date, ruthenium‐based electrocatalysts have shown the best turnover numbers (TONs) and turnover frequencies (TOFs) for water splitting [17,18,22] .…”