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Competition from hydrogen/oxygen evolution reactions and low solubility of N2 in aqueous systems limited the selectivity and activity on nitrogen fixation reaction. Herein, we design an aerobic‐hydrophobic Janus structure by introducing fluorinated modification on porous carbon nanofibers embedded with partially carbonized iron heterojunctions (Fe3C/Fe@PCNF‐F). The simulations prove that the Janus structure can keep the internal Fe3C/Fe@PCNF‐F away from water infiltration and endow a N2 molecular‐concentrating effect, suppressing the competing reactions and overcoming the mass‐transfer limitations to build a robust "quasi‐solid–gas" state micro‐domain around the catalyst surface. In this proof‐of‐concept system, the Fe3C/Fe@PCNF‐F exhibits excellent electrocatalytic performance for nitrogen fixation (NH3 yield rate up to 29.2 μg h−1 mg−1cat. and Faraday efficiency (FE) up to 27.8 % in nitrogen reduction reaction; NO3− yield rate up to 15.7 μg h−1 mg−1cat. and FE up to 3.4 % in nitrogen oxidation reaction). [ABSTRACT FROM AUTHOR]

Highlights: A triple functional additive with a trace amount (1 mM) was proposed to protect Zn anodes. The additive lowers the hydrogen evolution reaction potential, encourages the formation of an in situ solid electrolyte interphase and shields the "tip effect" Dendrite free Zn deposition and highly reversible Zn plating/stripping behaviors were realized by the triple protections Although their cost-effectiveness and intrinsic safety, aqueous zinc-ion batteries suffer from notorious side reactions including hydrogen evolution reaction, Zn corrosion and passivation, and Zn dendrite formation on the anode. Despite numerous strategies to alleviate these side reactions have been demonstrated, they can only provide limited performance improvement from a single aspect. Herein, a triple-functional additive with trace amounts, ammonium hydroxide, was demonstrated to comprehensively protect zinc anodes. The results show that the shift of electrolyte pH from 4.1 to 5.2 lowers the HER potential and encourages the in situ formation of a uniform ZHS-based solid electrolyte interphase on Zn anodes. Moreover, cationic NH4+ can preferentially adsorb on the Zn anode surface to shield the "tip effect" and homogenize the electric field. Benefitting from this comprehensive protection, dendrite-free Zn deposition and highly reversible Zn plating/stripping behaviors were realized. Besides, improved electrochemical performances can also be achieved in Zn//MnO2 full cells by taking the advantages of this triple-functional additive. This work provides a new strategy for stabilizing Zn anodes from a comprehensive perspective. [ABSTRACT FROM AUTHOR]

Molecular complexes with active metal centers exhibit high activity and selectivity for electrochemical CO2 reduction reaction (CO2RR), which represents a promising method for transforming greenhouse gas into valuable chemicals and feedstock. Using metal–organic frameworks (MOFs) to load the active molecular complexes then employing the combination with the carbonic conducting material may exhibit a beneficial effect for CO2RR. Herein, we obtained a composite catalyst named PCN-222(Fe)/CNTs, which was in situ synthesized through the solvothermal method that loads iron porphyrin-centered PCN-222(Fe) molecules onto CNTs. The catalyst PCN-222(Fe)/CNTs exhibits excellent electrocatalytic performance for CO2RR with a FECO of 95.5% (m(Fe-TCPP):m(CNTs) = 1:30, written as PCN-222(Fe)/CNTs-30) and an overpotential (η) of 494 mV. In addition, the turnover frequency (TOF) is high as 448.76 h−1 (3.011 site−1 s−1) and the hydrogen evolution reaction (HER) is indistinctive. After long-term electrocatalysis of 10 h at −0.6 V vs. RHE, PCN-222(Fe)/CNTs-30 remained its high catalytic performance with average FECO = 90%. This work provides a solid foundation for further research in the high-efficiency transformation of CO2 to CO. [ABSTRACT FROM AUTHOR]