Atomically dispersed metal-N-C structures are efficient active sites for catalyzing benzene oxidation reaction (BOR). However, the roles of N and C atoms are still unclear. We report a polymerization-regulated pyrolysis strategy for synthesizing single-atom Fe-based catalysts, and present a systematic study on the coordination effect of Fe-NxCy catalytic sites in BOR. The special coordination environment of single-atom Fe sites brings a surprising discovery: Fe atoms anchored by four-coordinating N atoms exhibit the highest BOR performance with benzene conversion of 78.4% and phenol selectivity of 100%. Upon replacing coordinated N atoms by one or two C atoms, the BOR activities decrease gradually. Theoretical calculations demonstrate the coordination pattern influences not only the structure and electronic features, but also the catalytic reaction pathway and the formation of key oxidative species. The increase of Fe-N coordination number facilitates the generation and activation of the crucial intermediate O=Fe=O species, thereby enhancing the BOR activity.

Co0.85Se@NC obtained by directly selenizing ZIF-67 can be used as a trifunctional catalyst for water splitting and Zn–air batteries.

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The development of efficient non-noble-metal electrocatalysts is of critical importance for clean energy conversion systems, such as fuel cells, metal-air batteries, and water electrolysis. Herein, uniform CoS@MoS core-shell heterostructures have been successfully prepared via a solvothermal approach, followed by an annealing treatment. Transmission electron microscopy, X-ray absorption near-edge structure, and X-ray photoelectron spectroscopy measurements reveal that the core-shell structure of CoS@MoS can introduce heterogeneous nanointerface between CoS and MoS, which can deeply influence its charge state to boost the electrocatalytic performances. Besides, due to the core-shell structure that can promote the synergistic effect of CoS and MoS and provide abundant catalytically active sites, CoS@MoS exhibits a superior hydrogen evolution reaction performance with a small overpotential of 143 mV at 10 mA cm and a small Tafel slope value of 117 mV dec under alkaline solution. Meanwhile, the activity of CoS@MoS toward oxygen evolution reaction is also impressive with a low operating potential (∼1.57 V vs reversible hydrogen electrode) at 10 mA cm. By using CoS@MoS catalyst for full water splitting, an alkaline electrolyzer affords a cell voltage as low as 1.67 V at a current density of 10 mA cm. Also, CoS@MoS reveals robust oxygen reduction reaction performance, making it an excellent catalyst for Zn-air batteries with a long lifetime (20 h). This work provides a new means for the development of multifunctional electrocatalysts of non-noble metals for the highly demanded electrochemical energy technologies.

The key descriptor that dominates the kinetics of the alkaline hydrogen evolution reaction (HER) has not yet been unequivocally identified. Herein, we focus on the adsorbed hydroxyl (OHad) transfer process (OHad + e− ⇄ OH−) and reveal its crucial role in promoting the overall kinetics of alkaline HER based on Ni/Co‐modified MoSe2 model catalysts (Ni‐MoSe2 and Co‐MoSe2) that feature almost identical water dissociation and hydrogen adsorption energies, but evidently different activity trends in alkaline (Ni‐MoSe2 ≫ Co‐MoSe2) and acidic (Co‐MoSe2 ≥ Ni‐MoSe2) media. Experimental and theoretical calculation results demonstrate that tailoring MoSe2 with Ni not only optimizes the hydroxyl adsorption, but also promotes the desorption of OH− and the electron‐involved conversion of OHad to OH−, all of which synergistically accelerate the kinetics of OHad + e− ⇄ OH− and thereby the overall kinetics of the alkaline HER.