Progress on nanostructured gel catalysts for oxygen electrocatalysis

Driven by the serious ecological problems, it is urgent to explore high-efficiency sustainable energy technologies. Oxygen electrocatalysis acts as important half-reactions in the emerging electrochemical energy techniques including electrolysis and batteries. Gel composites exhibit the merits of rich porous, superior hydrophilic, and large specific surface area, which can significantly improve the electrolyte penetration and boost the kinetics process of oxygen electrocatalysis. In this invited contribution, the advances and challenges of a novel gel materials for oxygen electrocatalysis are summarized. Starting from the structure–activity–performance relationship of gel materials, synthetic routes of nanostructured gel materials, namely, radical polymerization, sol-gel method, hydrothermal/solvothermal reactions, and ligand-substitution method, are introduced. Afterward, the gel composites are divided into polymer-based, metal-based, and carbon-based materials in turn, and their applications in oxygen electrocatalysis are discussed respectively. At the end, the perspective and challenges for advanced gel oxygen electrocatalysts are proposed.