Layer-by-Layer Assembly of CTAB-rGO-Modified MXene Hybrid Films as Multifunctional Electrodes for Hydrogen Evolution and Oxygen Evolution Reactions, Supercapacitors, and DMFC Applications

Abstract

Exceptional electrical conductivity and abundance of surface terminations like−F− and OH− leading to hydrophilicity make the family of 2D transition metal carbides/nitrides and carbonitrides (MXene) excellent candidates for energy storage and conversion applications. MXenes, however, undergo restacking of nanosheets via van der Waals interaction, hindering the active sites, leading to slow electronic and ionic kinetics, and ultimately affecting their electrochemical performance. Herein, we report binder-free cetyltrimethylammonium bromide-reduced graphene oxide (CTAB-rGO)-modified MXene hybrid films on nickel foam as a promising noble metal-free multifunctional electrode synthesized via layer-by-layer assembly and dip coating techniques, which effectively reduce restacking while improving the kinetics. The properties of the asprepared electrocatalysts are investigated using various physiochemical characterizations and electrochemical measurements to accomplish the objective of "creating one kind of electrocatalyst for multiapplication" with a thorough understanding of the relationship between the material structure, morphology, and electrocatalytic performance. In energy conversion, the synergetic effect of MXene and the CTAB-rGO support helped increase the catalytic activity of the composite for electrochemical water splitting, demonstrating a current density of 10 mA/cm 2 at an overpotential (η) of 360 V and a Tafel slope value of 56.6 mV/dec for hydrogen evolution reaction and a current density of 10 mA/cm 2 at an overpotential (η) of 179 mV and a Tafel slope value of 47.03 mV/dec for oxygen evolution reaction in an alkaline medium. The electrode material also exhibited a higher oxidation current density (373.60 mA/cm 2 ) compared to that of synthesized MXene toward methanol oxidation reaction in direct methanol fuel cell application. Additionally, the energy storage potential of CTAB-rGO modified MXene as electrode materials for supercapacitors with a high specific capacitance (544.50 F g −1 at 0.5 A g −1 ) and a good capacity retention of 87% after 5000 cycles was studied. These findings of this work showcase the potential of the electrocatalyst in both conversion and storage of electrochemical energy.

Binary Ni–Cu nanocomposite-modified MXene-adorned 3D-nickel foam for effective overall water splitting and supercapacitor applications

“…4 Accordingly, electric energy from energy conversion and storage devices such as lithium-ion batteries, 5,6 metal air batteries, 7,8 supercapacitors, 9–13 fuel cells 14,15 and electrochemical water splitting is becoming a more significant part of modern life due to its efficiency, sustainability, and greenness. 16–22 Owing to its ability to produce pure green hydrogen with high energy density as fuel together with zero carbon emission, electrochemical water splitting is considered a promising alternative. 23,24 Electrochemical water splitting is expected to replace fossil fuels given that it only requires mild electrolytic conditions to produce energy due to the production of high-purity environmentally friendly fuel with excellent activity.…”

Self-supported 3D coral-like copper/poly diphenylamine on nickel foam: multifunctional exploration of overall electrochemical water splitting, alcohol oxidation reaction and supercapacitor applications

“…35 Clean energy generation research revolves upon the design of highly stable and active multifunctional electrocatalysts with regulated size, shape, and composition and current research focuses on high-performance noble metal-free materials with more active sites density and good endurance. 36 There are numerous studies that have documented the efficacy of transition metal-based materials, including sulphides, oxide, nitrides, and alloys, as inexpensive and readily available multifunctional electrocatalysts for energy conversion processes. The weak conductivity resulting from its semiconducting nature, which significantly limits the performance and kinetic reaction rates, is the main reason why their electrochemical activity and durability are still far below expectations.…”