Molecular Catalytic Assemblies for Electrodriven Water Splitting

Abstract

Clean energy carriers obtained from renewable, earth‐abundant materials and by using the virtually unlimited supply of sunlight have potential to serve as future sustainable power sources. A quest for new materials for oxygen evolution from catalytic water oxidation and carbon dioxide reduction, which aim to build up solar‐to‐fuel conversion devices that use water as raw material, has been developing during the last two decades. Most of the research in the field of materials science and chemistry has been focused on the development of inorganic materials and molecular complexes for water oxidation, in particular bioinspired catalytic systems. Recently, various molecular water‐oxidation complexes with mono‐ or multinuclear catalytic sites have been tested for solution‐phase dioxygen generation. Catalyst immobilization and functionalization on an electrode surface is required for electrocatalytic or photoelectrochemical water oxidation devices; however, there are only a few examples in which a molecular catalyst has been placed on a transparent conducting surface in an electro‐ or photoelectrochemical system. Herein, a brief overview of surface‐immobilized molecular assemblies for electrochemical water oxidation is presented, and an analysis of recent progress in catalyst design and performance is provided, including systems integration of modules for future stand‐alone solar‐to‐fuel conversion devices. A view on the thermodynamics features of various intermediates and the mechanism of OO bond formation in single‐site complexes and binuclear water oxidation catalysts is also presented.

A Dynamic View of Proton-Coupled Electron Transfer in Photocatalytic Water Splitting

“…40 . The PCET nature of this process is also in agreement with the suggested catalytic mechanism 40,78 .…”

Surface Generation of a Cobalt‐Derived Water Oxidation Electrocatalyst Developed in a Neutral HCO3−/CO2 System

“…[1][2][3] In combination with CO 2 , a potent greenhouse gas, the electrons and protons generated from water splitting can be reduced directly to nonfossil liquid fuels. [ 4,5 ] This method provides an attractive route for solar fuel production and avoids the problems related to hydrogen safety and storage ( Figure 1 ). [ 6,7 ] The diffi culty in four electron abstraction from two water molecules and simultaneous formation of an O-O bond pose a great challenge for constructing a practical device for solar fuel production on a large scale.…”

Atomically monodisperse nickel nanoclusters as highly active electrocatalysts for water oxidation

“…Thus, the development of efficient water oxidation electrocatalysts (WOEc) is considered as a formidable challenge. 9 Recently, many molecular complexes, transition metals oxides and inorganic materials have been explored for water oxidation under electrochemical conditions. [9][10][11][12][13] Owing to the difficulties in the abstraction of four electrons from two water molecules and subsequent formation of an O-O bond, this process poses a great challenge to find a state of the art water splitting system.…”

“…9 Recently, many molecular complexes, transition metals oxides and inorganic materials have been explored for water oxidation under electrochemical conditions. [9][10][11][12][13] Owing to the difficulties in the abstraction of four electrons from two water molecules and subsequent formation of an O-O bond, this process poses a great challenge to find a state of the art water splitting system. 14,15 Therefore, there is a continuous effort to develop stable and robust catalytic material for water splitting that could be produced from economical and earth abundant materials, while operating at a modest overpotential and with a high oxygen evolution current density.…”