The development of highly efficient, stable, and lowcost catalysts for oxygen reduction and evolution reactions (ORR and OER, respectively) is vital for rechargeable metal−air batteries and united regenerative fuel cells. Herein, we develop a facile strategy for fabricating the heterojunction Co/Co 2 P nanocrystals that are confined in bamboo-like N-doped carbon nanotubes (Co/Co 2 P@NCNTs) on a large scale. In particular, operando X-ray absorption spectroscopy and electrochemical measurements were conducted to investigate the dynamic structural evolution of the precatalyst during electrocatalytic operation. Active state self-reconstruction from the Co/Co 2 P heterojunctions into Co 3+ octahedral site (Oh)-containing CoO x (OH) y active species is observed. Consequently, the high degree of graphitization of NCNTs with optimized N species and the completely triggered cross-linked CoO x (OH) y both contribute to the outstanding bifunctional ORR/OER activity (E gap = 0.68 V vs RHE) and durability. Meanwhile, the Co/Co 2 P@NCNTs as a precatalyst exhibits an ultralong cycling stability (cycling life of >1000 h) in rechargeable zinc−air flow batteries.
Ammonia is not only an important platform chemical for industrial and agricultural use but is also a novel energy‐carrying molecule. The electrochemical reduction method for ambient ammonia synthesis is emerging as a promising strategy for the replacement of the current Haber–Bosch ammonia synthesis method, which consumes a large amount of energy and natural gas (hydrogen resource) while releasing substantial greenhouse gases (eg, carbon dioxide). The challenges in electrochemical ammonia synthesis, also known as nitrogen reduction reaction, primarily include the cleavage of extremely stable N≡N bonds and the competitive hydrogen evolution reaction in routine aqueous media, which significantly leads to a low production rate and Faradaic efficiency. The rational design and engineering of the electrocatalyst/electrolyte interface are crucial to address these challenges. Herein, recent achievements for catalyst/electrolyte interface engineering are reviewed to provide insights into enhancing the production rate and Faradaic efficiency. Perspectives on future research and development of the electrochemical ammonia synthesis from theory to practice will be provided.
High‐performance oxygen electrocatalysts play a key role in the widespread application of rechargeable Zn–air batteries (ZABs). Single‐atom catalysts (SACs) with maximum atom efficiency and well‐defined active sites have been recognized as promising alternatives of the present noble‐metal‐based catalysts for oxygen reduction reaction and oxygen evolution reaction. To improve their oxygen electrocatalysis activities and reveal the structure–activity relationship, many advanced synthesis and characterization methods have been developed to study the effects of 1) coordination and electronic structure of the metal centers and 2) morphology and stability of the conductive substrates. Herein, a detailed review of the recent advances of SACs with strong electronic metal–support interaction (EMSI) for rechargeable ZABs is provided. Great emphasis was placed on the EMSI forms and design strategies. Moreover, the importance and the impact of the atomic coordinating structure and the substrates on the oxygen electrocatalytic activity and stability are highlighted. Finally, future directions and perspectives on the development of SACs are also presented.
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