Anchoring MnCo₂O₄ Nanorods from Bimetal-Organic Framework on rGO for High-Performance Oxygen Evolution and Reduction Reaction

Abstract

Oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are important reactions of energy storage and conversion devices. Therefore, it is highly desirable to design efficient and dual electrocatalysts for replacing the traditional noble-metal-based catalysts. Herein, we have developed a high-efficiency and low-cost MnCo2O4-rGO nanocomposite derived from bimetal-organic frameworks. For OER, MnCo2O4-rGO showed an onset potential of 1.56 V (vs reversible hydrogen electrode (RHE)) and a current density of 14.16 mA/cm2 at 1.83 V, being better than both pure MnCo2O4 and Pt/C. For ORR, MnCo2O4-rGO exhibited a half-wave potential (E1/2) of 0.77 V (vs RHE), a current density of 3.33 mA/cm2 at 0.36 V, a high electron transfer number n (3.80), and long-term stability, being close to the performance of Pt/C. The high activity of MnCo2O4-rGO was attributed to the synergistic effect among rGO, manganese, and cobalt oxide. As a result, the resultant MnCo2O4-rGO has a great potential to be applied as a high-efficiency ORR and OER electrocatalyst.

Ultrahigh Rate Capability and Lifespan MnCo2O4/Ni‐MOF Electrode for High Performance Battery‐Type Supercapacitor

“…This result is consistent with the information obtained by EDS. The atomic ratio of Co to Mn is calculated as 2 : 1, which is in accordance with the theoretical value [30] . The main peaks of Mn 2p 3/2 and Mn 2p 1/2 locate at 642.5 and 654.5 eV, respectively.…”

“…The atomic ratio of Co to Mn is calculated as 2 : 1, which is in accordance with the theoretical value. [30] The main peaks of Mn 2p 3/2 and Mn 2p 1/2 locate at 642.5 and 654.5 eV, respectively. By curve fitting, the peaks at 642.1 (Mn 2p 3/2 ) and 653.4 eV (Mn 2p 1/2 ) are attributed to Mn 2 + , and the peaks at 645.7 and 654.9 eV are attributed to Mn 3 + , [31,32] as shown in Figure 2b.…”

CuCo2S4@B,N-Doped Reduced Graphene Oxide Hybrid as a Bifunctional Electrocatalyst for Oxygen Reduction and Evolution Reactions

“…The number of electrons transferred ( n ) is accurately calculated using least-squares fitted slopes obtained from the Koutecky–Levich equation ( eq 1 ). 54 For this, LSV curves are carefully recorded at different rotating speeds typically ranging from 200 to 2400 rpm at a sweep rate of 10 mV s –1 , as presented in Figures 5 c and S3a–d of the Supporting information. With an increase in the rotation speed, the current density increases.…”

Recent Progress on NiFe‐Based Electrocatalysts for the Oxygen Evolution Reaction

“…[ 13 ] The OER involves four steps, with one electron coupled per step, while the HER is a two electron‐transfer reaction; consequently, the OER generally exhibits sluggish kinetics and requires a larger overpotential than the HER. [ 14–17 ] Hence, OER electrocatalyst design plays a key role in efficient water splitting. The proposed reaction mechanism for the OER under basic conditions is summarized as follows where* indicates the active site of the catalyst, and OH*, O*, and OOH* denote adsorbed intermediate species.…”

“…[13] The OER involves four steps, with one electron coupled per step, while the HER is a two electron-transfer reaction; consequently, the OER generally exhibits sluggish kinetics and requires a larger overpotential than the HER. [14][15][16][17] Hence, OER electrocatalyst design plays a key role in efficient water splitting. The proposed reaction mechanism for the OER under basic conditions is summarized as follows…”