Tiny Ni Nanoparticles Embedded in Boron- and Nitrogen-Codoped Porous Carbon Nanowires for High-Efficiency Water Splitting

Fei Guo; Zhuo Liu; Yiyong Zhang; Jie Xiao; Xiaoyuan Zeng; Chengxu Zhang; Peng Dong; Tingting Liu; Yingjie Zhang; Mian Li

doi:10.1021/acsami.2c04956

Tiny Ni Nanoparticles Embedded in Boron- and Nitrogen-Codoped Porous Carbon Nanowires for High-Efficiency Water Splitting

ACS Appl Mater Interfaces. 2022 Jun 1;14(21):24447-24461. doi: 10.1021/acsami.2c04956. Epub 2022 May 23.

Authors

Fei Guo¹, Zhuo Liu¹, Yiyong Zhang¹, Jie Xiao¹, Xiaoyuan Zeng¹, Chengxu Zhang¹, Peng Dong¹, Tingting Liu², Yingjie Zhang¹, Mian Li¹

Affiliations

¹ National and Local Joint Engineering Laboratory for Lithium-Ion Batteries and Materials Preparation Technology, Key Laboratory of Advanced Battery Materials of Yunnan Province, Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, PR China.
² School of Materials and Energy, Yunnan Key Laboratory for Micro/Nano Materials and Technology, Yunnan University, No. 2, Green Lake North Road, Kunming 650091, PR China.

PMID: 35604016
DOI: 10.1021/acsami.2c04956

Abstract

The integration of nickel (Ni) nanoparticle (NP)-embedded carbon layers (Ni@C) into the three-dimensional (3D) hierarchically porous carbon architectures, where ultrahigh boron (B) and nitrogen (N) doping is a potential methodology for boosting Ni catalysts' water splitting performances, was achieved. In this study, the novel 3D ultrafine Ni NP-embedded and B- and N-codoped hierarchically porous carbon nanowires (denoted as Ni@BNPCFs) were successfully synthesized via pyrolysis of the corresponding 3D nickel acetate [Ni(AC)₂·4H₂O]-hydroxybenzeneboronic acid-polyvinylpyrrolidone precursor networks woven by electrospinning. After optimizing the pyrolysis temperatures, various structural and morphological characterization analyses indicate that the optimal Ni@BNPCFs-900 networks own a large surface area, abundant micro/mesopores, and vast carbon edges/defects, which boost doping a large amount of B (5.81 atom %) and N (5.84 atom %) dopants into carbon frameworks with 6.36 atom % of BC₃, pyridinic-N (pyridinic-N-Ni), and graphitic-N active sites. Electrochemical measurements demonstrate that Ni@BNPCFs-900 reveals the best hydrogen evolution reaction (HER) and oxygen reduction reaction catalytic activities in an alkaline solution. The HER potential at 10 mA cm^-2 [E₁₀ = -164.2 mV vs reversible hydrogen electrode (RHE)] of the optimal Ni@BNPCFs-900 is just 96.2 mV more negative than that of the state-of-the-art 20 wt % Pt/C (E₁₀ = -68 mV vs RHE). In particular, the OER E₁₀ and Tafel slope of the optimal Ni@BNPCFs-900 (1.517 V vs RHE and 19.31 mV dec^-1) are much smaller than those of RuO₂ (1.557 V vs RHE and 64.03 mV dec^-1). For full water splitting, the catalytic current density achieves 10 mA cm^-2 at a low cell voltage of 1.584 V for the (-) Ni@BNPCFs-900||Ni@BNPCFs-900 (+) electrolysis cell, which is 10 mV smaller than that of the (-) 20 wt % Pt/C||RuO₂ (+) benchmark (1.594 V) under the same conditions. The synergistic effects of 3D hierarchically porous structures, advanced charge transport ability, and abundant active centers [such as Ni@BNC, BC₃, pyridinic-N (pyridinic-N-Ni), and graphitic-N] are responsible for the excellent water-splitting catalytic activity of the Ni@BNPCFs-900 networks. Especially, because of the remarkable structural and chemical stabilities of 3D hierarchically porous Ni@BNPCFs-900 networks, the (-) Ni@BNPCFs-900||Ni@BNPCFs-900 (+) water electrolysis cell displays an excellent stability.

Keywords: Ni@C nanoparticles; excellent stability; hierarchically porous carbon nanowires; hydrogen evolution reaction; nitrogen and boron codoping; oxygen evolution reaction.