Optimized Nanopores Opened on N-Doped Carbon Nanohorns Filled with Fe/Fe2O3 Nanoparticles as Advanced Electrocatalysts for the Oxygen Evolution Reaction

Yanli Nan; Zihan Zhang; Yuanyuan He; Jian Wei; Yun Zhou

doi:10.1021/acs.inorgchem.1c02416

Optimized Nanopores Opened on N-Doped Carbon Nanohorns Filled with Fe/Fe₂O₃ Nanoparticles as Advanced Electrocatalysts for the Oxygen Evolution Reaction

Inorg Chem. 2021 Nov 1;60(21):16529-16537. doi: 10.1021/acs.inorgchem.1c02416. Epub 2021 Oct 19.

Authors

Yanli Nan¹, Zihan Zhang¹, Yuanyuan He¹, Jian Wei¹, Yun Zhou²

Affiliations

¹ School of Materials Science and Engineering, Shaanxi Key Laboratory of Nano Materials and Technology, Xi'an University of Architecture and Technology, Xi'an 710055, China.
² School of Medical Information and Engineering, Southwest Medical University, Lu Zhou 646000, China.

PMID: 34665597
DOI: 10.1021/acs.inorgchem.1c02416

Abstract

N-doped carbon nanohorns filled with Fe nanoparticles (Fe-N-CNHs) were produced by one-step positive pressure-assisted arc discharge in the Ar and N₂ mixture. After oxidation treatments in air, Fe was converted into Fe₂O₃, and nanopores were opened on CNHs from 1 to 5 nm controlled by oxidation temperature. Fe-N-CNHs oxidized in O₂ at 550 °C (Fe₂O₃-N-CNH550ox) show 245 mV at 20 mA cm^-1, which is much smaller than that of the ones oxidized at 500 °C (Fe₂O₃-N-CNH500ox), contributing to the larger pore size on CNHs (3-5 nm vs 2-3 nm) and a larger number of nanopores caused by the enhanced sidewall nanopores. However, the stability of Fe₂O₃-N-CNH550ox becomes much poorer than that of Fe₂O₃-N-CNH500ox after 2000 cycles. The unique relationship between the overpotential and long-term stability can be explained by the consideration of the size of Fe₂O₃ nanoparticles and nanopores on CNHs. Furthermore, the stability for Fe₂O₃-N-CNH550ox can be rapidly increased after heat treatment in Ar for 1 h caused by shrinking the size of tip nanopores. Herein, we first reveal that the performance of OER is related to the nanopore size of carbon carriers and the catalyst of nanometal particles. The optimization of pore-opening conditions in carbon carriers can be achieved a superior electrocatalytic OER performance, including a low overpotential at high current density and long-term stability.