# Cobalt‐Based Catalysts for Electrochemical Water Splitting: Harnessing the Power of Ionic Liquids and Deep Eutectic Solvents

## TL;DR

This paper reviews how ionic liquids and deep eutectic solvents improve the design and performance of cobalt-based catalysts for water splitting.

## Contribution

The paper highlights the novel use of ILs and DESs as functional solvents and templates for controlled synthesis of cobalt catalysts.

## Key findings

- ILs and DESs enable structural and compositional control of cobalt catalysts.
- They enhance surface adsorption and stability of reaction intermediates.
- This leads to improved catalytic performance and product selectivity.

## Abstract

The emerging role of ionic liquids (ILs) and deep eutectic solvents (DESs) in the synthesis of cobalt‐based catalysts for water splitting is reviewed. ILs and DESs can serve as solvents and templates due to their unique physicochemical properties. They can efficiently dissolve raw materials and provide a special nucleation and growth environment, obtaining catalysts with novel structures. The designability of ILs and DESs allows for the controlled preparation of catalysts, where they can participate in the reaction as reactants, providing elements such as P, S, N, simplifying the preparation system of cobalt phosphide, sulfide, and nitride. ILs and DESs in catalyst synthesis achieve structural and compositional design, impacting surface adsorption and intermediate stability, allowing precise control over reaction paths and product selectivity. This leads to improved catalytic performance and stability. The review aims to succinctly summarize recent progress and guide researchers in selecting superior solvents for catalyst preparation.

Recent research has focused on using ionic liquids (ILs) and deep eutectic solvents (DESs) to prepare electrocatalysts. These solvents have unique physicochemical properties and are considered green media and functional materials. Cobalt‐based catalysts are commonly used for water splitting. ILs and DESs can improve their adsorption properties and reaction intermediate stability. This review summarizes recent advancements in using ILs and DESs for cobalt‐based catalyst preparation in water splitting, aiming to aid in the design and synthesis of novel and high‐performance electrochemical catalysts.© 2026 WILEY‐VCH GmbH