The development of low-cost, high-efficiency, and robust electrocatalysts for the oxygen evolution reaction (OER) is urgently needed to address the energy crisis. In recent years, non-noble-metal-based OER electrocatalysts have attracted tremendous research attention. Beginning with the introduction of some evaluation criteria for the OER, the current OER electrocatalysts are reviewed, with the classification of metals/alloys, oxides, hydroxides, chalcogenides, phosphides, phosphates/borates, and other compounds, along with their advantages and shortcomings. The current knowledge of the reaction mechanisms and practical applications of the OER is also summarized for developing more efficient OER electrocatalysts. Finally, the current states, challenges, and some perspectives for non-noble-metal-based OER electrocatalysts are discussed.

The exploration of highly active, durable, and cost-effective electrocatalysts for the oxygen reduction reaction (ORR) is indispensable for several important energy conversion technologies. Significant achievements have been made with numerous efforts devoted by the academic and industrial researchers. In this review, from a more practical point of view, the tests and experiments at the membrane electrode assembly (MEA) level are accentuated due to the fact that the rotating disk electrode (RDE) level performance cannot be transformed directly into the MEA level. Four major categories of the current ORR electrocatalysts are discussed, namely, platinum group metal (PGM or noble) catalysts, non-PGM catalysts, carbon-based catalysts, and single-atom-based catalysts. The advantages and shortcomings, along with the performance achieved by the catalysts, are briefly reviewed, and the improvement in the rational design approaches is emphasized at the full-cell level. Finally, the present challenges and prospects are discussed for developing advanced ORR electrocatalysts.

Porous CoFe O /C NRAs supported on nickel foam@NC (denoted as NF@NC-CoFe O /C NRAs) are directly fabricated by the carbonization of bimetal-organic framework NRAs grown on NF@poly-aniline(PANI), and they exhibit high electrocatalytic activity, low overpotential, and high stability for the oxygen evolution reaction in alkaline media.

Postsynthetic ion exchange of [Co2(μ-Cl)2(btta)] (MAF-X27-Cl, H2bbta =1H,5H-benzo(1,2-d:4,5-d')bistriazole) possessing open metal sites on its pore surface yields a material [Co2(μ-OH)2(bbta)] (MAF-X27-OH) functionalized by both open metal sites and hydroxide ligands, giving drastically improved electrocatalytic activities for the oxygen evolution reaction (an overpotential of 292 mV at 10.0 mA cm(-2) in 1.0 M KOH solution). Isotope tracing experiments further confirm that the hydroxide ligands are involved in the OER process to provide a low-energy intraframework coupling pathway.

In view of the clean and sustainable energy, metal–organic frameworks (MOFs) based materials, including pristine MOFs, MOF composites, and their derivatives are emerging as unique electrocatalysts for oxygen reduction reaction (ORR). Thanks to their tunable compositions and diverse structures, efficient MOF‐based materials provide new opportunities to accelerate the sluggish ORR at the cathode in fuel cells and metal–air batteries. This Minireview first provides some introduction of ORR and MOFs, followed by the classification of MOF‐based electrocatalysts towards ORR. Recent breakthroughs in engineering MOF‐based ORR electrocatalysts are highlighted with an emphasis on synthesis strategy, component, morphology, structure, electrocatalytic performance, and reaction mechanism. Finally, some current challenges and future perspectives for MOF‐based ORR electrocatalysts are also discussed.