Heterogenization of Ionic liquid Boosting Electrochemical Oxygen Reduction Performance of Co₃O₄ Supported on Graphene Oxide

Abstract

Electrochemical oxygen reduction is essential for a variety of sustainable energy application technologies. The development of non-noble metal based electrocatalysts with durable stability and lower overpotentials is still a challenge. According to the reaction mechanism, the difficulty is originated from large equilibrium potential for *OO À formation and high instability of it. Here, we synthesized a 2D electrocatalytic material with nano-Co 3 O 4 supported on ionic liquid-functionalized graphene oxide (Co 3 O 4 /ILÀ GO). Experimental results show the heterogenization strategy of IL enables anodic shifts of approximately 150 and 145 mV for the initial and half-wave potentials, respectively, enabling Co 3 O 4 /ILÀ GO a comparable activity to the state-of-the-art Pt/C catalyst. Moreover, Co 3 O 4 /ILÀ GO exhibits an excellent tolerance to methanol and superior long-term stability over Pt/ C making it a promising candidate for ORR in alkaline solutions. Theoretical calculations show the functionalized IL stabilizes the high-energy CoÀ OO À intermediate through a strong pairing effect between the IL cation and the unstable *OO À adduct, and lowers the energy barrier for the subsequent CoÀ OOH formation, which enables the hybrid material a comparable activity and superior durability to Pt/C. To the best of our knowledge, this is the first exploration for heterogenization of IL onto electrode to stabilize crucial intermediates and subsequently boost the catalytic performance.

Carbon-Based Catalysts for Selective Electrochemical Nitrogen-to-Ammonia Conversion

“…The 3d transition metals (e.g., Fe, Co, Ni and Cu) have been extensively investigated for electrochemical applications. − Recently, these earth abundant metals were also studied for electrochemical NRR. An isolated Fe-based single site catalyst embedded on N-doped carbon (ISAS-Fe/NC) was obtained by carbonization of Fe-ZIF method .…”

Enhanced Electrochemical Nitrate‐to‐Ammonia Performance of Cobalt Oxide by Protic Ionic Liquid Modification

“…The electron transfer process between Co 3 O 4−x and [Bim]NTf 2 was also confirmed by FTIR spectra. As shown in Figure S18, the absorption peak at 1195 cm −1 of [Bim]NTf 2 belonging to the stretching vibration of C−N bond on the imidazole ring [15b, 17] displayed a red shift to 1164 cm −1 after coating onto Co 3 O 4−x , which could be interpreted as the increase in electron cloud density of [Bim]NTf 2 caused by the electron injection from Co 3 O 4−x . In short, the Lewis acidity of the Co center in Co 3 O 4−x was efficiently improved through [Bim]NTf 2 and [HOOC(CH 2 ) 3 mim]NTf 2 modification, thus facilitating the adsorption of NO 3 − and answered for the enhanced reactivity of NITRR.…”

Recent Progress on Carbon‐Based Electrocatalysts for Oxygen Reduction Reaction: Insights on the Type of Synthesis Protocols, Performances and Outlook Mechanisms

“…[36] Establishing simple synthesis procedures by altering intermediate stabilizers of the ionic liquid on graphene oxide surfaces is an exciting research topic that assures efficient electrocatalytic materials for ORR. [37] Zhang et al synthesized an ionic liquid (IL) modified nitrogen and sulfur-doped graphene oxide (IL-SNG) using a mild hydrothermal method and explored its ORR activity in alkaline media. IL-SNG was prepared by dehydrating carboxylic groups on graphene oxide (GO) and amino groups on IL-NH 2 .…”

“…The elemental reaction shown in Figure 24f(i) is also exothermic, with a small energy barrier of 0.48 eV, as shown in Figure 24f(ii), implying that the ORR on C 8 F graphene in an alkaline media in LH mechanism proceeds by a 4e À process, as demonstrated by the three elemental steps below (Eqs. [35][36][37]:…”

“…Co‐doping carbon materials with heteroatoms increases the potential and limit current density, but lacks rational design, making future performance promotion difficult [36] . Establishing simple synthesis procedures by altering intermediate stabilizers of the ionic liquid on graphene oxide surfaces is an exciting research topic that assures efficient electrocatalytic materials for ORR [37] …”