Imidazolatic-Framework Bimetal Electrocatalysts with a Mixed-Valence Surface Anchored on an rGO Matrix for Oxygen Reduction, Water Splitting, and Dye Degradation

Raja Palani; Venkatasamy Anitha; Chelladurai Karuppiah; Subramanian Rajalakshmi; Ying-Jeng Jame Li; Tai-Feng Hung; Chun-Chen Yang

doi:10.1021/acsomega.1c01870

Imidazolatic-Framework Bimetal Electrocatalysts with a Mixed-Valence Surface Anchored on an rGO Matrix for Oxygen Reduction, Water Splitting, and Dye Degradation

ACS Omega. 2021 Jun 11;6(24):16029-16042. doi: 10.1021/acsomega.1c01870. eCollection 2021 Jun 22.

Authors

Raja Palani¹, Venkatasamy Anitha², Chelladurai Karuppiah¹, Subramanian Rajalakshmi³, Ying-Jeng Jame Li¹, Tai-Feng Hung¹, Chun-Chen Yang^{1

4

5}

Affiliations

¹ Battery Research Center of Green Energy, Ming Chi University of Technology, New Taipei City 24301, Taiwan, R.O.C.
² Departmet of Chemistry, Sri G.V.G Visalakshi College for Women (Autonomous), Udumalpet 642128, India.
³ Department of Chemistry, Erode Arts and Science College (Autonomous), Erode 638112, India.
⁴ Department of Chemical Engineering, Ming Chi University of Technology, New Taipei City 24301, Taiwan, R.O.C.
⁵ Department of Chemical and Materials Engineering, Chang Gung University, Kwei-shan, Taoyuan 333, Taiwan, R.O.C.

Abstract

This paper presents a simple strategy for manufacturing bifunctional electrocatalysts-graphene nanosheets (GNS) coated with an ultrafine NiCo-MOF as nanocomposites (denoted NiCo-MOF@GNS) having a N-doped defect-rich and abundant cavity structure through one-pool treatment of metal-organic frameworks (MOFs). The precursors included N-doped dodecahedron-like graphene nanosheets (GNS), in which the NiCo-MOF was encompassed within the inner cavities of the GNS (NiCo-MOF@GNS) at the end or middle portion of the tubular furnace with several graphene layers. Volatile imidazolate N _x species were trapped by the NiCo-MOF nanosheets during the pyrolysis process, simultaneously inserting N atoms into the carbon matrix to achieve the defect-rich porous nanosheets and the abundantly porous cavity structure. With high durability, the as-prepared nanomaterials displayed simultaneously improved performance in the oxygen reduction reaction (ORR), the oxygen evolution reaction (OER), and photocatalysis. In particular, our material NiCo-MOF@GNS-700 exhibited excellent electrocatalytic activity, including a half-wave potential of 0.83 V (E _{ORR, 1/2}), a low operating voltage of 1.53 V (E _{OER, 10}) at 10 mA cm^-2, a potential difference (ΔE) of 1.02 V between E _{OER, 10} and E _{ORR, 1/2} in 0.1 M KOH, and a low band gap of 2.61 eV. This remarkable behavior was due to the structure of the defect-rich porous carbon nanosheets and the synergistic impact of the NPs in the NiCo-MOF, the N-doped carbon, and NiCo-N _x . Furthermore, the hollow structure enhanced the conductivity and stability. This useful archetypal template allows the construction of effective and stable bifunctional electrocatalysts, with potential for practical viability for energy conversion and storage.