The bimetallic center catalyst (DMC) injects new vitality into the accelerated oxygen reduction reaction (ORR) due to its unique structure. The regulation of the coordination environment composition and spatial structure of metal active centers also provides opportunities for optimizing the performance. Herein, we have successfully constructed stereoisomeric Fe2CN-bridge-S (abbreviated as Fe2CN-b-S) catalysts based on the biomimetic Fe–S cluster structure of ferredoxin. Adjacent Fe dual atoms skillfully weaken the O–O bond, crafting a peroxide bridge-like adsorption configuration. The incorporation of S atoms meticulously constructs the stereo configuration of active Fe sites, thereby inducing greater structural deformation tension and a downward shift in the Fe d-band center. These factors collectively facilitate the release of the OH* intermediate. Meanwhile, the reasonable spatial configuration of S can promote the optimal rigid structure of Fe diatomic active centers, improving the stability of the ORR reaction process. Thus, the Fe2CN-b-S catalyst, which has a half-wave potential of 0.865 V, demonstrates superior ORR activity in comparison to Fe2CN. This study offers a perspective on the joint regulation of elemental composition and geometric arrangement for enhanced catalytic activity in oxygen reduction.
Wang Shiwen,Liu Min,Hu Dongping,Dong Zhicheng,Zhao Zhong
Superoxide anion is thought to be a natural by-product with strong oxidizing ability in all living organisms and was recently found to accumulate in plant meristems to maintain stem cells in the shoot and undifferentiated meristematic cells in the root. Here we show that the DNA demethylase repressor of silencing 1 (ROS1) is one of the direct targets of superoxide in stem cells. The Fe–S clusters in ROS1 are oxidized by superoxide to activate its DNA glycosylase/lyase activity. We demonstrate that superoxide extensively participates in the establishment of active DNA demethylation in the Arabidopsis genome and that ARABIDOPSIS RESPONSE REGULATOR 12 acts downstream of ROS1-mediated superoxide signaling to maintain stem cell fate. Our results provide a mechanistic framework for superoxide control of the stem cell niche and demonstrate how redox and DNA demethylation interact to define stem cell fate in plants.
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