Implement Metal-Free Strategies for Oxygen Evolution Reaction with a Focus on Carbon and Polymers

The oxygen evolution reaction (OER) presents a significant challenge in developing electrochemical energy storage and conversion systems. Although non-noble metals exhibit commendable OER activity, their widespread application is often constrained by stability issues and elevated costs for large-scale deployment. As a result, the focus is shifting from non-noble metals to metal-free catalysts, which offer both abundance and effective catalytic performance. Metal-free catalysts, including carbon-based materials and polymers, typically demonstrate suboptimal catalytic activity in their pure forms. These materials are often doped with other metal-free substances to enhance their performance and modify their electronic structures, increasing the availability of active sites and facilitating improved electron flow for enhanced OER performance. This review examines the latest advancements in the creation of metal-free catalysts for OER and the associated challenges and opportunities within the expanding field of metal-free electrocatalysis. It aims to provide a comprehensive overview of metal-free OER catalysts for researchers entering this dynamic study area.