Exploring the Potential of MBenes Supercapacitors: Fluorine-Free Synthesized MoAl_1–xB with Ultrahigh Conductivity and Open Space

Abstract

The present study describes the synthesis of multilayered MBenes MoAl1–x B with different degrees of Al deintercalation using a mild, fluorine-free approach of dilute alkali to remove Al from MoAlB. We propose an etching route and compare it to conventional fluoride etching products. Additionally, the study explores the possible application and energy storage mechanism of MBenes in supercapacitors, marking the first investigation of its kind. At room temperature, 1/24-MoAl1–x B with terminal groups −OH exhibits ∼25% Al removal in 1 wt % NaOH for 24 h, outperforming traditional etching technology. Increasing the Al removal exposed more open space, resulting in a higher capacitance. Compared to LiF/HCl-MoAl1–x B (etched by LiF + HCl), 1/24-MoAl1–x B has a higher energy storage capability. The multilayered 1/24-MoAl1–x B film electrode exhibits ultrahigh conductivity with a rapid relaxation time of 0.97 s and high areal capacitance (2006.60 mF cm–2) while maintaining 80.2% capacitance after 5000 cycles. The MoAl1–x B all-solid-state supercapacitor (ASSS) delivers a high capacitance of 741.6 mF cm–2 at 1 mV s–1 for a single electrode and exhibits stable capacitance even at a 90° bending angle, highlighting its potential practical use. Our research represents an important step in the synthesis of MBenes and highlights their potential applications in supercapacitors.

Layered MoxBy (MBenes) derived by a molten-salt method and their application in advanced LIB anodes

“…2e, the Al 2p spectrum of MoAlB performed three fitted peaks centered at 71.9, 74.2 and 74.8 eV, corresponding to elemental Al, MoAlB and Al 2 O 3 respectively. 39,40 Furthermore, similar to MoAlB, the Mo 3d spectrum of MBene-620 was also fitted to three couples for MBene, Mo-metal and Mo 6+ , respectively, as illustrated in Fig. 2f.…”

Recent Developments and Future Perspectives of Molybdenum Borides and MBenes

“…Partially “Al” etched MoAlB nanosheets are reported to show good energy storage performance when used as the electrodes of supercapacitors (Table 1 ). [ 70 , 71 , 72 ] 2D MBenes applied as the pseudocapacitive filter electrochemical supercapacitor electrode material exhibited excellent AC filtering performance with a specific capacitance of 702 mFcm −2 under the AC condition of 120 Hz and a negative phase angle of 54.8°. [ 70 ] All‐solid‐state supercapacitors based on multilayered MBenes delivered significant capacitance, high energy density, and power density even at a 90° bending angle ( Figure 7 ).…”

“…[ 70 ] All‐solid‐state supercapacitors based on multilayered MBenes delivered significant capacitance, high energy density, and power density even at a 90° bending angle ( Figure 7 ). [ 71 ] Vinoth et al demonstrated the asymmetric supercapacitors based on MoB nanosheets and activated carbon as the electrodes with 1 M H 2 SO 4 and 1 M Na 2 SO 4 as the electrolytes. [ 72 ] The asymmetric device delivered a high energy density of 14 WhKg −1 at a power density of 16.8 kWKg −1 .…”

“…Fabrication and electrochemical measurements for 1/24-MoAl 1−x B all-solid-state supercapacitor (ASSS), a) Photographs of a 1 × 1.5 cm 2 film electrode bent to various shapes, b) Photographs of ASSS bent to different bending angles (0, 30, 45, and 90°), c) Thickness of the fabricated ASSS, d)CV curves under different bending angles, e) capacitance under different bending angles, f) capacitance retention of the single electrode, g) Nyquist plots, h) Galvanostatic charge-discharge (GCD) curves, i) Ragone plots. Reprinted with permission [71]. Copyright 2023.…”

2D MoB MBene: An Efficient Co-Catalyst for Photocatalytic Hydrogen Production under Visible Light

“…Similar to MXene, another 2D nanomaterial, MBene is obtained by selectively etching an A element from the precursor MAB phase (M is an early transition metal, A is a group A element, and B stands for boron element) . Theoretical calculations and experiments demonstrate the potential applications for MBene in catalysis, − magnetic devices, energy storage , and conversion, biotechnology, solid lubrication, gas absorption, etc . Among various MBenes, MoB MBene has attracted great research attention in recent years due to the prospective catalytic activity provided by Mo sites.…”