Mn-Based Hierarchical Polyhedral 2D/3D Nanostructures MnX₂ (X = S, Se, Te) Derived from Mn-Based Metal–Organic Frameworks as High-Performance Electrocatalysts for the Oxygen Evolution Reaction

Abstract

Three-dimensional (3D) nanomaterials are being explored extensively to serve as efficient electrocatalyts, which can be designed through the modification of electronic states of active sites in energy conversion applications. In this work, for the first time, a series of hierarchical polyhedral 3D nanostructures of Fe-doped manganese-based chalcogenides MnX2 (X = S, Se, Te) incorporating amorphous carbon (C) is synthesized using an Mn-based metal–organic framework as the precursor via a two-step hydrothermal route. The MnX2/C hierarchical polyhedral nanostructures (HPNs) (X = S, Se, Te) display remarkable results such as lower overpotentials of 305, 276, and 246 mV at a current density of 10 mA cm–2 and small Tafel slopes of 85, 90, and 48 mV dec–1, respectively. Moreover, iron-doped MnX2 (Fe–MnX2/C-HPNs, X = S, Se, Te) display improved electrocatalytic activity, achieving lower overpotentials of 280, 246, and 210 mV at a current density of 10 mA cm–2 and smaller Tafel slopes of 85, 65, and 48 mV dec–1, respectively. The enhanced efficiency of two-dimensional (2D)/3D hierarchical polyhedral nanostructures (Fe–MnX2/C-HPNs, X = S, Se, Te) is due to the larger specific surface area, easy charge transport, and integrated amorphous carbon. Hence, the construction of exceptionally efficient and low-cost electrocatalysts could be facilitated by this MOF-template approach for multilayer nanostructured materials for future applications.

Nanoengineering of NiO/MnO2/GO Ternary Composite for Use in High-Energy Storage Asymmetric Supercapacitor and Oxygen Evolution Reaction (OER)

“…Linear sweep and cyclic voltammetry (CV) were conducted at a scan rate of 10 mVs − 1 without iR compensation in a 1.0 M KOH solution. The recorded electrode potential vs. Ag/AgCl was calculated and calibrated to reference hydrogen electrode (RHE) using the formula E (RHE) = E Ag/AgCl + 0.0592 pH + 0.196 [ 31 , 32 ]. The electrochemical active surface area (ECSA) was calculated from the double-layer specific capacitance by performing cyclic voltammetry (CV) at various scan rates of 5, 10, 15, 20, 25, 30, 35, 40, 45, and 50 mVs − 1 in a potential window of 0−0.2 V vs. Ag/AgCl.…”

Investigation of Active Spots on a TiC@MnSe Nanocomposite: An Efficient Electrocatalyst for the Oxygen Evolution Reaction

“…All polarization curves were iR-corrected. All measured voltages were estimated in the RHE (reversible hydrogen electrode) relationship by using the following equation 32,33…”

“…All polarization curves were iR -corrected. All measured voltages were estimated in the RHE (reversible hydrogen electrode) relationship by using the following equation , E RHE = E Ag / AgCl + 0.059 × pH + E o The alkaline KOH solution has a pH of 13.6, which needs to be compensated based on the voltage drop. The Tafel slope and excess reaction energy of the OER reaction can be determined as η = b nobreak0em0.1em⁡ log nobreak0em0.25em⁡ j + a η = E RHE − 1.23 The C dl was calculated to assess the ECSA.…”

In‐Situ Growth of Cu2S‐MoS2 Bimetallic Electrocatalyst on Carbon Cloth for Hydrogen Evolution Reaction

“…Non-noble metal-based catalysts such as sulfides, [11][12][13][14] carbides, [16,17] nitrides, [18][19][20] selenides, [21][22] phosphides [23][24][25][26] and their derivatives [27][28][29][30] have been proved to be efficient electrocatalysts for HER. MoS 2 nanosheets are one kind of typical twodimensional (2D) electrocatalytic materials, which have been aroused widespread attentions as graphene-like layered structure, low cost, Pt-like behavior and suitable H adsorption energy.…”