Electrodeposition of (hydro)oxides for an oxygen evolution electrode.

Zhenhua Yan,Jun Chen,Meng Yu,Huanhuan Liu,Xiang Chen,Zhimeng Hao

doi:10.1039/d0sc01532f

Abstract

Electrochemical water splitting is a promising technology for hydrogen production and sustainable energy conversion, but the electrolyzers that are currently available do not have anodic electrodes that are robust enough and highly active for the oxygen evolution reaction (OER). Electrodeposition provides a feasible route for preparing freestanding OER electrodes with high active site utilization, fast mass transport and a simple fabrication process, which is highly attractive from both academic and commercial points of view. This minireview focuses on the recent electrodeposition strategies for metal (hydro)oxide design and water oxidation applications. First, the intrinsic advantages of electrodeposition in comparison with traditional technologies are introduced. Then, the unique properties and underlying principles of electrodeposited metal (hydro)oxides in the OER are unveiled. In parallel, illustrative examples of the latest advances in materials structural design, controllable synthesis, and mechanism understanding through the electrochemical synthesis of (hydro)oxides are presented. Finally, the latest representative OER mechanism and electrodeposition routes for OER catalysts are briefly overviewed. Such observations provide new insights into freestanding (hydro)oxides electrodes prepared via electrodeposition, which show significant practical application potential in water splitting devices. We hope that this review will provide inspiration for researchers and stimulate the development of water splitting technology.

Highlights

As an ideal energy carrier with an ultrahigh caloric value and CO2-free emissions, hydrogen is considered as the ultimate chemical energy source.[1,2,3]
The anodic four-electron transfer oxygen evolution reaction (OER) in water splitting typically requires a larger overpotential than the cathodic two-electron hydrogen evolution reaction (HER) (Fig. 1B).[5]
Under OER conditions, conductive carbon and most materials are prone to be oxidized and etched at a high overpotential, resulting in the strong deterioration of electrode performance.[6]. Another difficulty is that rigorous bubble release under high current density will inevitably cause serious bubble-shielding effects and catalyst peel off issues.[7,8]

Summary

Introduction

As an ideal energy carrier with an ultrahigh caloric value and CO2-free emissions, hydrogen is considered as the ultimate chemical energy source.[1,2,3] Electrochemical splitting of water into hydrogen and oxygen provides a promising route to produce hydrogen. It stores intermittent energies such as solar and wind in the form of chemical energy (Fig. 1A).[4] This green route allows the production of high-level hydrogen with almost zero carbon emissions. The anodic four-electron transfer oxygen evolution reaction (OER) in water splitting typically requires a larger overpotential than the cathodic two-electron hydrogen evolution reaction (HER) (Fig. 1B).[5] The equilibrium potential of oxygen evolution is as high as 1.23 V vs RHE. Another difficulty is that rigorous bubble release under high current density will inevitably cause serious bubble-shielding effects and catalyst peel off issues.[7,8]

Objectives

Conclusion